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[vsnet-grb-info 40852] GRB 251118A: Glowbug gamma-ray detection
by GCN Circulars 20 Nov '25

20 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42784 SUBJECT: GRB 251118A: Glowbug gamma-ray detection DATE: 25/11/20 20:44:33 GMT FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung(a)nrl.navy.mil> C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 251118A, which was also detected by Fermi/GBM (GCN 42743, 42745, 42783), Fermi/LAT (GCN 42752), NuSTAR (GCN 42774), and GECAM-B (GCN 42779). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-11-18 20:31:43.57 with a duration of 47.1 s and a total significance of over 360 sigma. The light curve comprises two peaks at ~T0+1.5s and +37s, matching the two brightest peaks in the Fermi/GBM and GECAM-B lightcurves. The initial faint emission at the GBM trigger time (20:31:30) may be present in the Glowbug light curve at low significance. The GRB was detected despite the elevated background due to Glowbug being in and exiting the Southern polar region at the time of the burst. Note that data throughout the burst interval suffered from deadtime in various detectors. The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42784. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40851] GRB 251118A: Fermi GBM Observation
by GCN Circulars 20 Nov '25

20 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42783 SUBJECT: GRB 251118A: Fermi GBM Observation DATE: 25/11/20 19:37:15 GMT FROM: Eva MP <eva.palafox(a)gmail.com> Eva Palafox (INAOE) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 20:31:30.09 UT on 18 November 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251118A (trigger 785190695/251118855), which was also detected by Fermi-LAT (R. Gupta et al. 2025, GCN 42752), Swift/XRT (J.P. Osborne et al. 2025, GCN 42782), GECAM-B (Yang-Zhao Ren et al., 2025, GCN 42779) and NuSTAR (G. Waratkar et al. 2025, GCN 42774). The Fermi GBM final real-time localization (GCN 42743) is consistent with the Fermi-LAT position. The angle from the Fermi LAT boresight is 69 degrees. The GBM light curve consists of a faint emission episode, followed by very bright emission episodes, with a total duration (T90) of about 46.6 s (50-300 keV). The time-averaged spectrum from T0-2.8 to T0+87.3 s is best fit by a Comptonized function with Epeak = 149.3 +/- 2.0 keV, and alpha = -1.40 +/- 0.01. A Band function fits equally well with Epeak = 134.0 +/- 2.7, alpha = -1.36 +/- 0.01, and beta = -2.56 +/- 0.06. The event fluence (10-1000 keV) in this time interval is (1.03 +/- 0.01)E-04 erg/cm^2. The 1-sec peak photon flux measured starting from T0+52 s in the 10-1000 keV band is 96 +/- 0.7 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" View this GCN Circular online at https://gcn.nasa.gov/circulars/42783. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40850] GRB 251118A: Swift-XRT afterglow detection
by GCN Circulars 20 Nov '25

20 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42782 SUBJECT: GRB 251118A: Swift-XRT afterglow detection DATE: 25/11/20 13:53:24 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-OAR), D.N. Burrows (PSU), S. Lanava (PSU), S. Dichiara (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Fermi/LAT-detected burst GRB 251118A. We searched for X-ray sources in 3.0 ks of Photon Counting (PC) mode data. The total exposure at the position of the afterglow (see below) is 5.4 ks, obtained between T0+31.3 ks and T0+108.8 ks. Two uncatalogued X-ray sources are detected, of which one ("Source 1") is above the RASS 3-sigma upper limit at this position, and is therefore likely the GRB afterglow. Using 3939 s of PC mode data and 7 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 160.00418, -34.52259 which is equivalent to: RA (J2000): 10h 40m 01.00s Dec(J2000): -34d 31' 21.3" with an uncertainty of 2.0 arcsec (radius, 90% confidence). This position is 5.0 arcmin from the Fermi/LAT position. The light curve can be modelled with a power-law decay with a decay index of alpha=1.08 (+0.18, -0.16). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.73 (+0.16, -0.15). The best-fitting absorption column is 2.2 (+0.7, -0.6) x 10^21 cm^-2, in excess of the Galactic value of 8.3 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.1 x 10^-11 (5.2 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.2 (+0.7, -0.6) x 10^21 cm^-2 Galactic foreground: 8.3 x 10^20 cm^-2 Excess significance: 3.9 sigma Photon index: 1.73 (+0.16, -0.15) The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/00021890. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/00021890. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42782. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40849] GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
by GCN Circulars 20 Nov '25

20 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42781 SUBJECT: GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis DATE: 25/11/20 09:43:04 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> N. Dagoneau, B. Hubert, S. Schanne (CEA), J.-L. Atteia (IRAP), C.-W. Wang (IHEP) Using the event-by-event data downloaded through the X-band ground station, we report further analysis of SVOM/ECLAIRs and SVOM/GRM observations of GRB 251103A (SVOM burst-id sb25110301, GCN 42534, GCN 42552), which was also detected by NOT (GCN 42535), Fermi/GBM (GCN 42536), LCO (GCN 42538), BOOTES-2/TELMA (GCN 42539), GOTO (GCN 42543), SVOM/COLIBRI (GCN 42549), Swift-XRT (GCN 42551), Fermi/GBM (GCN 42553), Swift/UVOT (GCN 42554), Kilonova-Catcher (GCN 42559), WINTER (GCN 42562), Global MASTER-Net (GCN 42565), Swift/BAT-GUANO (GCN 42568), KAIT (GCN 42571), Insight-HXMT (GCN 42572), Xinglong 2.16m (GCN 42573), OHP/T193 (GCN 42574), WFST (GCN 42577), ZTF (GCN 42579) The burst that triggered ECLAIRs shows a light-curve consisting of two peaks: a soft precursor occurring from T0-4s to T0+2s mainly in the 4-30 keV energy band (T0=2025-11-03T04:46:21 UTC), and a main peak occurring from T0+2s to T0+16s in the 4-120 keV energy band. The event has a total duration of 20s (T90 is not a good measure in this case, because it covers incompletely both peaks). ECLAIRs triggered onboard on both peaks, GRM only detected the main peak. Using an analysis of the ECLAIRs data alone, the time-averaged spectrum of the precursor (from T0-4 s to T0+2 s) in the 8-20 keV energy band is best fitted by a power-law model with a photon index of -3.01 -0.2/+0.3, indicating a very soft spectrum (while a simple black-body model does not provide a good fit). With this model, the mean energy fluence in 4-120 keV is (4.97 +/- 2.73)E-08 erg/cm^2. The time-averaged spectrum of the main peak (from T0+2 s to T0+16 s) in the 8-120 keV energy band is best fitted by a cutoff power-law model with a photon index of -1.18 -0.02/+0.12 and a cutoff energy parametrized as Epeak of 122 +/- 26 keV. With this model, the mean energy fluence in 4-120 keV is (4.14 +/- 0.19)E-06 erg/cm^2. Using a joint analysis of ECLAIRs and GRM data, the time-averaged spectrum of the main peak (T0+2 s to T0+16 s) in the 8-1000 keV energy band is best fitted by a Band model with a low-energy photon index of -1.12 +/-0.04, a high-energy photon index of -2.04 -0.11/+0.08 and a cutoff energy parametrized as Epeak of 116 +/- 23 keV. With this model, the mean energy fluence in 10-1000 keV is (8.33 +/- 0.58)E-06 erg/cm^2. With a redshift of z = 0.76 (GCN 42540), the isotropic equivalent energy of this burst Eiso (from 1 keV to 10 MeV in its rest frame) is 2.01 +/- 0.14 10^52 erg, which makes this GRB consistent with type II GRBs in the 'Amati' relation diagram (Amati et al. 2002). All the quoted errors are at the 68% confidence level. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM point of contact for this burst is: Nicolas Dagoneau (nicolas.dagoneau AT cea.fr) View this GCN Circular online at https://gcn.nasa.gov/circulars/42781. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40848] EP251118a: Optical detection with Kinder observations
by GCN Circulars 20 Nov '25

20 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42780 SUBJECT: EP251118a: Optical detection with Kinder observations DATE: 25/11/20 09:35:57 GMT FROM: Amar Aryan at National Central University, Institute of Astronomy (NCUIA) <amararyan941(a)gmail.com> Y.-H. Lee, A. Aryan, C.-S. Lin (all NCU), A. K. H. Kong (NTHU), T.-W. Chen (NCU), J. Gillanders, S. J. Smartt (both Oxford), Y. J. Yang (NYUAD), A. Sankar.K, Y.-C. Pan, C.-C. Ngeow, M.-H. Lee, C.-H. Lai, W.-J. Hou, H.-C. Lin, H.-Y. Hsiao, J.-K. Guo (all NCU), S. Yang, Z. N. Wang, L. L. Fan, G. H. Sun (all HNAS), H.-W. Lin (UMich), H. F. Stevance, S. Srivastav, L. Rhodes (all Oxford), M. Nicholl, M. Fulton, T. Moore, K. W. Smith, C. Angus, A. Aamer (all QUB), A. Schultz and M. Huber (both IfA, Hawaii) report: We observed the field of the fast X-ray transient EP251118a (Jiang et al., GCN 42749) using the 1m LOT at Lulin Observatory in Taiwan as part of the Kinder collaboration (Chen & Yang et al., 2025, ApJ, 983, 86). The first LOT epoch of observations started at 16:21 UTC on the 19th of November 2025 (MJD 60998.681), 23.64 hr after the EP-WXT trigger. We utilized the astroalign (Beroiz et al. 2020, A&C, 32, 100384) and astropy (Astropy Collaboration et al. 2022, ApJ, 935, 167) packages to align and stack the individual frames. We utilized the Python-based package AutoPhOT (Brennan & Fraser, 2022, A&A, 667, A62) to perform template subtraction with the DESI Legacy Survey (Dey et al. 2019, AJ 157, 168) DR10 image using the 'hotpants' (Becker A., 2015, ascl.soft. ascl:1504.004) algorithm. In the difference image, we clearly detected the optical counterpart candidate proposed by Malesani et al. (GCN 42751) at a spectroscopic redshift of z = 1.216 (An et al., GCN 42756), and confirmed by Belkin et al. (GCN 42758); Yadav et al. (GCN 42760); Busmann et al. (GCN 42763); Francile et al. (GCN 42767); and Urquijo-Rodríguez et al. (GCN 42773). Moreover, we further utilized AutoPhOT to perform the PSF photometry. The details of the observations and the measured magnitude(in the AB system) are as follows: Telescope | Filter | MJD (start) | t-t0 (hr) | Exposure (s) | Magnitude | avg. Seeing | med. Airmass LOT | r | 60998.681 | 23.64 | 300 * 6 | 21.136 +/- 0.049 | 1".47 | 1.67 The presented magnitude is calibrated using the field stars from the ATLAS-RefCat2 catalog from MAST (Tonry J. L. et al. 2018, ApJ, 867, 105) and is not corrected for the expected Galactic foreground extinction of A_r = 0.034 mag in the direction of the transient (Schlafly & Finkbeiner 2011). The methodology, details on the Lulin observatory telescopes, and a compilation of our optical follow-up campaign for FXTs discovered within the first year of operation of the Einstein-Probe mission can be found in Aryan et al. 2025, ApJS, 281, 20, doi:10.3847/1538-4365/adfc69. View this GCN Circular online at https://gcn.nasa.gov/circulars/42780. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40847] GRB 251118A: GECAM-B detection
by GCN Circulars 20 Nov '25

20 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42779 SUBJECT: GRB 251118A: GECAM-B detection DATE: 25/11/20 08:32:34 GMT FROM: renyz16607(a)163.com Yang-Zhao Ren, Chen-Wei Wang, Chao Zheng, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered in-flight by a long burst, GRB 251118A, at 2025-11-18T20:31:30.089 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #42743), Fermi/LAT (Gupta et. al., GCN #42752), and NuSTAR (Waratkar et. al., GCN #42774). According to the GECAM-B light curves in about 40-6000 keV, this burst mainly consists of multiple pulses with a duration (T90) of 46.2 +0.2/-0.3 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb251118A.png The time-averaged spectrum from T0-1.9 s to T0+71.0 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.54 +0.09/-0.09 and the cutoff energy, parameterized as Epeak, is 99.8 +4.4/-4.5 keV. The event fluence (10-1000 keV) in this time interval is (1.01 +0.04/-0.04)E-04 erg/cm^2. The 'Amati' relation diagram of GRB 251118A is shown at: https://www.bursthub.cn//admin/static/gecambgrb251118A_amati.png Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS). View this GCN Circular online at https://gcn.nasa.gov/circulars/42779. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40846] EP-WXT trigger 01709248403: confirmation of a stellar flare by SVOM/VT
by GCN Circulars 20 Nov '25

20 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42778 SUBJECT: EP-WXT trigger 01709248403: confirmation of a stellar flare by SVOM/VT DATE: 25/11/20 07:22:12 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Y. N. Ma, Z. H. Yao, Y. Xu, X. H. Han, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. R. Xu, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team. SVOM/VT performed ToO observation on the EP-WXT trigger 01709248403 (Li et al. GCNC 42775). The observation began on 2025-11-19T19:32:02 UT (i.e. 37 min post trigger) in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously . The counterpart PM J02028+0447 was decreasing in brightness from 12.57 mag at 40 min to 12.67 mag at 78 min in VT_B band, confirming this event as due to a stellar flare, as already suggested by the EP team (Li et al. GCNC 42775). The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS. View this GCN Circular online at https://gcn.nasa.gov/circulars/42778. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40845] LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
by GCN Circulars 20 Nov '25

20 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42777 SUBJECT: LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results DATE: 25/11/20 07:21:34 GMT FROM: Yinuo Ma <mayn(a)bao.ac.cn> Y. N. Ma, L. P. Xin, Z. H. Yao, Y. L. Qiu, C. Wu, H. L. Li, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team. SVOM/VT performed the Target of Opportunity observations of 3 candidates of S251112cm reported by LIGO/Virgo/KAGRA (GCN 42650, GCN 42690). SVOM/VT began observing the field at 2025-11-17, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. We observed AT2025adhf (GCN 42675, GCN 42724), AT2025adkl (GCN 42691), and AT2025addc (GCN 42658), which were reported by the Vera C. Rubin Observatory (GCN 42707). We found that AT2025adhf is located within a galaxy, while AT2025adkl is situated at a galaxy's edge. Here we provide the total magnitudes of the supernovae and the galaxies (using the galactic nuclei as the photometric center), since we do not have the templates for this sources. AT2025addc is an isolated source, and we also provide its magnitude. The magnitudes are: Name |Observation Date(UTC) |VT_B(AB_mag) |VT_R(AB_mag) ----------------------|----------------------|-------------|------------- AT2025adhf(+galaxy) |2025-11-17 |17.19+-0.01 |16.41+-0.01 AT2025adkl(+galaxy) |2025-11-18 |20.14+-0.05 |19.50+-0.04 AT2025addc |2025-11-17 |20.45+-0.04 |20.75+-0.07 Our photometry was not corrected for Galactic extinction. Further analysis of these candidates is ongoing. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS. View this GCN Circular online at https://gcn.nasa.gov/circulars/42777. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40844] EP251118a / GRB 251118C: SVOM/VT optical observation
by GCN Circulars 20 Nov '25

20 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42776 SUBJECT: EP251118a / GRB 251118C: SVOM/VT optical observation DATE: 25/11/20 06:52:54 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Y. N. Ma, Z. H. Yao, Y. Xu, X. H. Han, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. R. Xu, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team. SVOM/VT performed ToO observation on EP251118a/GRB 251116C (Jiang et al., GCN 42749; Shi et al., GCN 42754; Frederiks et al., GCN 42765; Wang et al., GCN 42766; Delaunay et al., GCN 42770; Woolf et al, GCN 42771). The observation started at 2025-11-19T07:02:19 UT, i.e. 14.33 hour after EP-WXT staring time in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. The optical counterpart reported by Malesani et al. (GCN 42751) and other optical observations (An et al., GCN 42756; Belkin et al, GCN 42758; Yadav et al., GCN 42760; Busmann et al., GCN 42763; Francile et al., GCN 42767; Urquijo-Rodríguez et al., GCN 42773) was clearly detected by VT in both channels. The measurements in AB magnitudes were derived as below: Mid time | Band | Exposure Time | Magnitudes (AB) 15.84 hour VT_B 20*70 sec 21.07+/-0.05 mag 15.84 hour VT_R 20*70 sec 20.64+/-0.05 mag Our photometry was not corrected for Galactic extinction. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS. View this GCN Circular online at https://gcn.nasa.gov/circulars/42776. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40843] The EP-WXT trigger 01709248403 is likely a flaring star
by GCN Circulars 20 Nov '25

20 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42775 SUBJECT: The EP-WXT trigger 01709248403 is likely a flaring star DATE: 25/11/20 01:36:45 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> R.-Z. Li (YNAO, CAS), J. Yang (ZZU), R. Shi (PMO, CAS), F.-F. Song (YNAO, CAS), C. L. Guo and H. Sun (NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709248403 at the time of 2025-11-19T18:55:22, is likely a stellar flare associated with a High Proper Motion Star PM J02028+0447. The estimated flux of the flare is around 2.6e-10 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 1.3e31 erg/s. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/42775. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40842] GRB 251118A: NuSTAR detection of bright prompt emission
by GCN Circulars 20 Nov '25

20 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42774 SUBJECT: GRB 251118A: NuSTAR detection of bright prompt emission DATE: 25/11/20 00:26:27 GMT FROM: Gaurav Waratkar at Caltech <gauravwaratkar(a)iitb.ac.in> G. Waratkar (Caltech) and B. Grefenstette (Caltech) report on behalf of the NuSTAR Search for INteresting Gamma-ray Signals (SINGS) working group: The NuSTAR SINGS working group reports the detection of prompt emission from the long-duration GRB 251118A in both the NuSTAR CsI anti-coincidence shields. This GRB was identified through a blind search using the CsI shield rates. Details of the search algorithm will be described in a future paper. The NuSTAR SINGS algorithm triggered at 2025-11-18 20:32:21.000 (with a resolution ~5-seconds). This is consistent with the detections of GRB 251118A by Fermi/GBM (Fermi GBM Team, GCN Circ. 42743) and Fermi/LAT (Gupta et al., GCN Circ. 42752). The NuSTAR CsI shield data are recorded at 1 Hz. We do not detect the first two bursts as seen in the Fermi/GBM lightcurve (GCN Circ. 42743) and detect the third bright burst. The burst appears to be composed of one bright peak lasting for ~9-s. The peak count rate is ~3000-cps over a baseline rate of ~1,000-cps during this time period. We do not see any evidence in the signal above 100 keV in the CdZnTe detectors. The Fermi/LAT localization (GCN Circ. 42752) at RA = 160.08, Dec = -34.58 implies an offset from the NuSTAR boresight of 140-deg and an offset from the geocenter of 99-deg. Lightcurves and analysis for this GRB can be found here: https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/reports/2025/251118A Information on NuSTAR SINGS can be found here: https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/ NuSTAR is a NASA Small Explorer mission led by Caltech and managed by JPL for NASA's Science Mission Directorate in Washington. View this GCN Circular online at https://gcn.nasa.gov/circulars/42774. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40841] EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42773 SUBJECT: EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO DATE: 25/11/19 23:38:46 GMT FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf(a)iac.es> E. Urquijo-Rodríguez, J. Basurto Merino, P.G. Berdayes, A. Caballero-Almagro, A. Cerón, M. Contreras, F. Díaz-Segado, T. Ferrer-Laviña, B. Gandolfi, V. Ghiraldo, J. Hernández Fung, L. Juliá-Maroto, E. Lekaroz-Urriza, M. Manzano García, E. Mejía-Martínez, J. Prieto Polo, M. Pulido-Torres, M. Quintana-Ansaldo, A. Schenone-Zanuzzi, A. Selezneva, T. Tundidor Rodríguez (all ULL), M. Abdul-Masih (IAC and ULL), and I. Pérez-Fournon (IAC and ULL). Following the detection of the fast X-ray transient EP251118a by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Jiang et al., GCN circ. 42749) and by the EP Follow-up X-ray Telescope (FXT) (Shi et al., GCN circ. 42754), we observed the field with one of the three Las Cumbres Observatory (LCO) 1-m telescopes equipped with Sinistro cameras located at the LCO node at Cerro Tololo Inter-American Observatory (CTIO), Chile. The observation, a single exposure of 500 sec in the SDSS r' filter, started on 2025-11-19 at 07:58:16 UT, about 15.26 hours after the EP-WXT trigger. The optical counterpart first detected by NOT ALFOSC (Malesani et al., GCN 42751), at a redshift of z = 1.216 (An et al., GCN circ. 42756) is clearly detected in our image with a magnitude of r' = 20.69 +/- 0.06 (AB), calibrated against PanSTARRS-1 DR2 stars and not corrected for Galactic extinction. Our result is consistent with other optical and near-infrared observations: Belkin et al. (GCN circ. 42758), Yadav et al. (GCN circ. 42760), Busmann et al. (GCN circ. 42763), and Francile et al. (GCN circ. 42767). EPP251118a is likely associated with the long-duration GRB 251118C detected by Konus-Wind (Frederiks et al., GCN circ. 42765), SVOM/GRM (Wang et al., GCN circ. 42766), Swift/BAT (DeLaunay et al., GCN circ. 42770),and Glowbug (Woolf et al., GCN circ. 42771). This work makes use of observations from the Las Cumbres Observatory global telescope network (LCO program IAC2025B-010). These observations are part of a course in Astrophysical Techniques of the Master in Astrophysics of the Astrophysics Department of the University of La Laguna in collaboration with the Instituto de Astrofísica de Canarias (La Laguna, Tenerife, Canary Islands, Spain). This work made use of the Astro-COLIBRI platform (P. Reichherzer et al. 2021, ApJS, 256, 5). View this GCN Circular online at https://gcn.nasa.gov/circulars/42773. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40840] GRB 251116C: NOT optical observations
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42772 SUBJECT: GRB 251116C: NOT optical observations DATE: 25/11/19 22:04:25 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani(a)nbi.ku.dk> G. Corcoran (UCD), D. B. Malesani (DAWN/NBI and Radboud), A. Martin-Carrillo (UCD), L. Fuglsang (NOT) report on behalf of a larger collaboration: We observed the location of the SVOM/ECLAIRs (Pillas et al., GCN 42703; Brunet et al., GCN 42703) and Swift/BAT (DeLaunay et al., GCN 42726) GRB 251116C, using the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Our observation covers ~90% of the 3'-radius BAT error circle (including XRT source #1; Evans et al., GCN 42721), and consists of six 300-s images in the r band, taken at a mean epoch of 2025 Nov 17.910 UT (1.245 days after the trigger). Inside or in close proximity of XRT source #1, four objects (3 point-like) are detected in both the NOT and Legacy Survey images. Their photometry does not show significant variation by more than ~0.1 mag. Image subtraction was performed using the Legacy Survey as reference template. No new sources are detected within the covered fraction of the BAT error circle, down to a 3 sigma limiting magnitude of r > 24.4. Our non-detection is consistent with the earlier reports by LCO (Turpin et al., GCN 42705) and SVOM/VT (Li et al., GCN 42712). View this GCN Circular online at https://gcn.nasa.gov/circulars/42772. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40839] GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42771 SUBJECT: GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A DATE: 25/11/19 20:54:02 GMT FROM: richard.s.woolf.civ(a)us.navy.mil R. Woolf, C.C. Cheung, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 251118C, a possible gamma-ray counterpart of EP251118A (GCN 42749), also detected by Konus-Wind (GCN 42765), SVOM/GRM (GCN 42766), and Swift/BAT (GCN 42770). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-11-18 16:44:45.264 with a duration of 8.2 s and a total significance of about 23.8 sigma. The light curve comprises a single primary peak. Note that data from ~T0+8s to ~T0+12s suffered from deadtime in various detectors. The best-fit localization is RA, Decl. (J2000, deg) = 125.0, 14.2 with a radius of 10.5 deg (95% confidence), with a highly uncertain systematic uncertainty. The Glowbug position for GRB 251118C is consistent with that reported for the fast X-ray transient EP251118A (GCN 42749). The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42771. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40838] GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42770 SUBJECT: GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A DATE: 25/11/19 20:06:57 GMT FROM: Jimmy DeLaunay at Penn State <delauj2(a)gmail.com> James DeLaunay (PSU), Samuele Ronchini (GSSI), Aaron Tohuvavohu (Cosmic Frontier), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC), Maia Williams (Northwestern) report: Swift/BAT did not localize GRB 251118C onboard (T0: 2025-11-18T16:44:49 UTC, Konus-Wind GCN 42765, SVOM/GRM GCN 42766) Due to the lack of prompt trigger, the Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1) was unable to save time-tagged event data around this burst. The GRB is clearly detected in the BAT rates data with a S/N ~ 13. The emission is seen starting at ~T0 - 12 s and lasts ~28 s. There are minimal counts seen at energies less than 50 keV, which is consistent with a GRB that is outside the coded field of view of BAT, especially with the soft spectrum observed by Konus-Wind and SVOM/GRM. There is also a 10 s time tagged event data file during the burst due to an onboard rate trigger that failed to recover an image position. We used the 10 s of event data to create an image (15 - 350 keV) and find no new sources in it. Due to the lack of sources in the image and the observed energy spectrum, this GRB is likely to be outside the 10% coded field of view of Swift/BAT. Also, we can confirm that the GRB is not Earth Occulted for Swift. This rules out a circular region of the sky centered at ra, dec = 21.69, 12.65 deg (J2000) with a radius of 69.5 deg. This rules out only ~half of the sky, and does not rule out the position of EP 251118A (GCN 42749). There are no NITRATES results due to the lack of GUANO data, but the rates light-curve and position of the Earth and BAT coded FoV at the time can be seen on the results summary page https://guano.swift.psu.edu/trigger_report?id=785177125 View this GCN Circular online at https://gcn.nasa.gov/circulars/42770. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40837] GRB 251018A: FRAM-Auger optical detection
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42769 SUBJECT: GRB 251018A: FRAM-Auger optical detection DATE: 25/11/19 20:02:40 GMT FROM: Martin Jelinek at Astro.Inst-AVCR,Ondrejov <martin.jelinek(a)asu.cas.cz> Anurag Talele (University of Potsdam), Martin Jelinek, Alzbeta Malenakova, Jan Strobl (ASU CAS Ondrejov, CZ), Filip Novotny (ASU Ondrejov + Masaryk University), Martin Masek, Petr Janecek, Sergey Karpov, Jakub Jurysek, Jan Ebr, Ronan Cunniffe, Petr Travnicek and Michael Prouza (Institute of Physics, Prague, CZ) report: The 30 cm robotic telescope at the FRAM-Auger in Malargue (Argentina) reacted robotically to the Swift/BAT alert of GRB251018A (trigger 1405083, Gupta et. al. GCN42343) issued at 03:12:02 UT. FRAM obtained its first unfiltered exposure 42 seconds after the trigger, at 03:12:44 UT, followed by a sequence of 20s and 60s exposures. An optical transient is detected at the UVOT position. It appears at R(Vega) roughly 15.5 mag at T0 + 78s and fades to roughly 18.0 mag by the end of our 28 minutes observing run consistent with detections by Lipunov et. al. GCN42346, Hu et. al. GCN42363 and Kuin et. al. GCN42353. View this GCN Circular online at https://gcn.nasa.gov/circulars/42769. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40836] GRB 251117A: Swift-XRT observations
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42768 SUBJECT: GRB 251117A: Swift-XRT observations DATE: 25/11/19 18:06:28 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , D.N. Burrows (PSU), S. Lanava (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Fermi/GBM-detected burst GRB 251117A in a series of observations tiled on the sky. The total exposure time is 6.5 ks, distributed over 7 tiles; the maximum exposure at a single sky location in the tiling was 2.0 ks. The data were collected between T0+48.9 ks and T0+81.8 ks, and are entirely in Photon Counting (PC) mode. Thirteen uncatalogued X-ray sources have been detected, however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Details of these sources are given below: Source 1: RA (J2000.0): 331.2065 = 22h 04m 49.57s Dec (J2000.0): +5.5085 = +05d 30' 30.6" Error: 8.0 arcsec (radius, 90% conf.) Count-rate: (7.5 [+4.2, -3.1])e-3 ct s^-1 Distance: 401 arcsec from Fermi/GBM position. Flux: (2.8 [+1.5, -1.1])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 2: RA (J2000.0): 331.2121 = 22h 04m 50.90s Dec (J2000.0): +5.6862 = +05d 41' 10.4" Error: 18.7 arcsec (radius, 90% conf.) Count-rate: (4.4 [+2.7, -1.9])e-3 ct s^-1 Distance: 523 arcsec from Fermi/GBM position. Source 3: RA (J2000.0): 331.1150 = 22h 04m 27.61s Dec (J2000.0): +5.1842 = +05d 11' 03.0" Error: 8.5 arcsec (radius, 90% conf.) Count-rate: (7.0 [+4.5, -3.2])e-3 ct s^-1 Distance: 1539 arcsec from Fermi/GBM position. Source 6: RA (J2000.0): 331.1130 = 22h 04m 27.12s Dec (J2000.0): +5.7560 = +05d 45' 21.6" Error: 7.8 arcsec (radius, 90% conf.) Count-rate: (8.2 [+4.5, -3.4])e-3 ct s^-1 Distance: 947 arcsec from Fermi/GBM position. Flux: (2.8 [+1.5, -1.2])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 7: RA (J2000.0): 331.5308 = 22h 06m 07.38s Dec (J2000.0): +5.4134 = +05d 24' 48.2" Error: 6.5 arcsec (radius, 90% conf.) Count-rate: (4.9 [+2.6, -1.9])e-3 ct s^-1 Distance: 1000 arcsec from Fermi/GBM position. Source 8: RA (J2000.0): 331.7897 = 22h 07m 09.54s Dec (J2000.0): +5.6746 = +05d 40' 28.6" Error: 7.8 arcsec (radius, 90% conf.) Count-rate: (7.1 [+4.4, -3.1])e-3 ct s^-1 Distance: 1794 arcsec from Fermi/GBM position. Source 9: RA (J2000.0): 330.9021 = 22h 03m 36.49s Dec (J2000.0): +5.4483 = +05d 26' 54.0" Error: 8.3 arcsec (radius, 90% conf.) Count-rate: (7.3 [+4.4, -3.3])e-3 ct s^-1 Distance: 1491 arcsec from Fermi/GBM position. Flux: (3.5 [+2.1, -1.6])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 10: RA (J2000.0): 331.7481 = 22h 06m 59.54s Dec (J2000.0): +5.3975 = +05d 23' 51.1" Error: 8.5 arcsec (radius, 90% conf.) Count-rate: 0.0109 [+0.0053, -0.0040] ct s^-1 Distance: 1721 arcsec from Fermi/GBM position. Source 11: RA (J2000.0): 330.8986 = 22h 03m 35.66s Dec (J2000.0): +5.4101 = +05d 24' 36.5" Error: 8.6 arcsec (radius, 90% conf.) Count-rate: (8.4 [+4.7, -3.5])e-3 ct s^-1 Distance: 1549 arcsec from Fermi/GBM position. Source 12: RA (J2000.0): 330.9379 = 22h 03m 45.11s Dec (J2000.0): +5.3847 = +05d 23' 05.0" Error: 7.1 arcsec (radius, 90% conf.) Count-rate: (9.1 [+4.8, -3.5])e-3 ct s^-1 Distance: 1458 arcsec from Fermi/GBM position. Source 13: RA (J2000.0): 330.8498 = 22h 03m 23.95s Dec (J2000.0): +5.4122 = +05d 24' 44.0" Error: 9.1 arcsec (radius, 90% conf.) Count-rate: (5.8 [+4.2, -2.8])e-3 ct s^-1 Distance: 1710 arcsec from Fermi/GBM position. Source 14: RA (J2000.0): 330.7987 = 22h 03m 11.70s Dec (J2000.0): +5.6452 = +05d 38' 42.7" Error: 9.8 arcsec (radius, 90% conf.) Count-rate: (6.7 [+4.2, -3.0])e-3 ct s^-1 Distance: 1816 arcsec from Fermi/GBM position. Source 15: RA (J2000.0): 330.9250 = 22h 03m 42.01s Dec (J2000.0): +5.4456 = +05d 26' 44.0" Error: 32.4 arcsec (radius, 90% conf.) Count-rate: (5.7 [+4.1, -3.1])e-3 ct s^-1 Distance: 1416 arcsec from Fermi/GBM position. Flux: (1.79 [+1.29, -0.96])e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV) The results of the XRT-team automatic analysis of the tiled XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00141. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42768. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40835] EP251118A / GRB 251118C : MASTER optical counterpart observations
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42767 SUBJECT: EP251118A / GRB 251118C : MASTER optical counterpart observations DATE: 25/11/19 17:40:22 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> Carlos Francile, Ricardo Podesta, Federico Podesta (OAFA), V. Lipunov, A.Kuznetsov, E.Gorbovskoy, G.Antipov, P.Balanutsa, I. Panchenko, N. Tiurina, K.Zhirkov, Ya.Kechin, A.Chasovnikov, V.Topolev, D. Vlasenko, Yu. Tselik, V.Senik (Lomonosov MSU, SAI, Moscow), E. Gonzalez (OAFA, San Juan Uni., Argentina), D. Buckley (SAAO, South Africa), O. Gress, N.Budnev, O.Ershova (Irkutsk State University), A. Sosnovskij (CrAO RAS), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), V.M.Pillet, R.Rebolo Lopez (The Instituto de Astrofisica de Canarias,Spain), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino, J.Martinez,A.R.Corella,L.H.Rodriguez (INAOE, Guillermo Haro Astrophysic Observatory, Mexico) MASTER-OAFA robotic telescope (Global MASTER Net [1-4],http://observ.pereplet.ru) located in Argentina started EP251118A (EP:Jiang et al. GCN 42749, Shi et al. GCN 42754, Konus-Wind: Frederiks et al. GCN 42765 as GRB 251118C) at 2025-11-19 07:57:04 UT (Lipunov et al. GCN 42755) There is optical transient MASTER OT J081239.45+105619.7 with m_OT=19.8 at 2025-11-19 07:57:04UT (calibrated by Gaia G). This optical counterpart of GRB 251118C was discovered by NOT (Malesani et al. GCN 42751) and also observed by VLT (Yadav et al. GCN 42760) and FTW (Busmann et al. GCN 42763) MASTER observations started at 45 degrees altitude (Sun_alt=-17deg) View this GCN Circular online at https://gcn.nasa.gov/circulars/42767. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40834] GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42766 SUBJECT: GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a DATE: 25/11/19 17:18:22 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Zheng-Hang Yu, Chao Zheng, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Maria-Grazia Bernardini (INAF-OAB) Report on behalf of the SVOM team: SVOM/GRM was triggered on-ground by a soft burst GRB 251118C at 2025-11-18T16:44:48.500 UTC (T0). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a single pulse with a T90 of 29 +22/-12 s in the 15-5000 keV band, which is also detected by Kouns-Wind (D. Frederiks et al., GCN#42765). The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251118C.png We note that the time coincidence between EP251118a (S. Q. Jiang et al., GCN#42749) and GRB 251118C suggest the association of these two events. In addition, the position of this burst, if is associated with EP251118a (RA= 123.160, DEC= 10.952, GCN#42749), is located at about 136 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. With this localization, the time-averaged spectrum from T0-6 to T0+17 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.86 +0.17/-0.09 and the cutoff energy, parameterized as Epeak, is 44 +37/-21 keV. The event fluence (10-1000 keV) in this time interval is (7.82 +0.84/-0.83)E-06 erg/cm^2. The time-averaged spectrum is also well fitted by a power law function with a power law index of -2.4 +0.15/-0.16, corresponding to a fluence of (1.00 +0.12/-0.11)E-05 erg/cm^2. The 1s peak spectrum, measured from T0-0.5 to T0+0.5 s, if fitted by a power law function with an exponential high-energy cutoff, the power law index is -1.83 +0.25/-0.12 and the cutoff energy, parameterized as Epeak, is 64 +55/-33 keV. The flux (10-1000 keV) in this time interval is (9.47 +1.30/-1.29)E-06 erg/cm^2/s. Assuming the redshift z= 1.216 (J. An et al., GCN#42756), the localization of GRB 251118C in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb251118C_amati.png And the localization in the 'Yonetoku' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb251118C_yonetoku.png We caution that this analysis based on the BREAKFAST framework is very preliminary [1]. Refined analysis will be reported later. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang(a)ihep.ac.cn) [1] Chen-Wei Wang et al. arXiv: 2510.15816 [astro-ph.HE] https://arxiv.org/abs/2510.15816 View this GCN Circular online at https://gcn.nasa.gov/circulars/42766. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40833] Konus-Wind detection of GRB 251118С (EP251118a)
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42765 SUBJECT: Konus-Wind detection of GRB 251118С (EP251118a) DATE: 25/11/19 16:58:51 GMT FROM: Dmitry Frederiks at Ioffe Institute <fred(a)mail.ioffe.ru> D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: A long-duration GRB 251118C was detected by Konus-Wind (KW) in the waiting mode at T0=T0(KW)~16:44:49 UT. A Bayesian block analysis of the KW data in the 20-1500 keV band reveals a ~17 sigma count rate increase in the interval from ~T0-0.5 s to ~T0+23 s. Corrected for the propagation time, the burst started ~140 s after the start time of the fast X-ray transient EP251118a (T0(EP)=16:42:29 UT; Jiang et al., GCN 42749). The burst source is located in the southern ecliptic hemisphere at a low ecliptic latitude, which is consistent with the EP251118a localization. The positional and temporal coincidence of GRB 251118C with the EP251118a supports the conclusion that both events have a common origin. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB251118C/ The time-integrated spectrum of the burst, measured from T0-0.5 s to T0+23 s, can be described by a simple power function with the photon index (2.29 ± 0.11). The total burst fluence is (5.08 ± 0.40)x10^-6 erg/cm^2, and the 2.944 s peak energy flux, measured from T0-1.96 s, is (4.84 ± 0.38)x10^-7 erg/cm^2(both in the 20 - 1500 keV energy range). Assuming the redshift z=1.216 (An et al., GCN 42756) and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the burst isotropic energy release E_iso to (2.06 ± 0.16)x10^52 erg, the isotropic peak luminosity L_iso to (4.34 ± 0.34)x10^51 erg/s. All the quoted errors are estimated at the 68% confidence level. All the presented results are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/42765. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40832] The EP-WXT trigger 01709248388 is likely a flaring star
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42764 SUBJECT: The EP-WXT trigger 01709248388 is likely a flaring star DATE: 25/11/19 15:27:22 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Q. C. Liu (THU), D. F. Hu, Q. J. Huang, R. Shi (PMO, CAS), F. F. Song (YNAO, CAS), S. Q. Jiang, C. C. Jin (NAO, CAS) report on behalf of the Einstein Probe team: The EP-WXT trigger 01709248388 at 2025-11-19T13:12:46 is likely a stellar flare associated with one of the two stars, RX J0423.5+0955 or RX J0423.5+0955B, that lie within the FXT error circle. The estimated flux of the flare is around 6e-11 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 9e+31 erg/s. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/42764. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40831] The EP-WXT trigger 01709248388 is likely a flaring star
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42764 SUBJECT: The EP-WXT trigger 01709248388 is likely a flaring star DATE: 25/11/19 15:27:22 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Q. C. Liu (THU), D. F. Hu, Q. J. Huang, R. Shi (PMO, CAS), F. F. Song (YNAO, CAS), S. Q. Jiang, C. C. Jin (NAO, CAS) report on behalf of the Einstein Probe team: The EP-WXT trigger 01709248388 at 2025-11-19T13:12:46 is likely a stellar flare associated with one of the two stars, RX J0423.5+0955 or RX J0423.5+0955B, that lie within the FXT error circle. The estimated flux of the flare is around 6e-11 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 9e+31 erg/s. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/42764. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40830] EP251118a: FTW optical and NIR observations
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42763 SUBJECT: EP251118a: FTW optical and NIR observations DATE: 25/11/19 15:14:34 GMT FROM: Malte Busmann at Ludwig-Maximilians-Universität München <m.busmann(a)physik.lmu.de> Malte Busmann (LMU), Xander J. Hall (CMU), Brendan O'Connor (CMU), Daniel Gruen (LMU), and Antonella Palmese (CMU) report: We observed the counterpart of EP251118a (Jiang et al., GCN 42749; Malesani et al., GCN 42751; Shi et al., GCN 42754; An et al., GCN 42756) with the Three Channel Imager (3KK) at the Fraunhofer Telescope at Wendelstein Observatory (FTW) in the r, i, and J bands simultaneously for 5 x 180 s starting at 2025-11-19T04:06:56 UT (0.48 days after the trigger). The counterpart is detected in all bands. Using Legacy Survey templates for difference imaging, we measure an r-band magnitude of r = 20.56 +/- 0.04 AB mag. Our measurements are consistent with the reports by Malesani et al. (GCN 42751), Lipunov et al. (GCN 42755), Belkin et al. (GCN 42758), and Yadav et al. (GCN 42760). The magnitude is calibrated against the PS1 catalog and not corrected for Galactic extinction. We thank Michael Schmidt from the Wendelstein Observatory for obtaining these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42763. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40829] GRB 251117A: Insight-HXMT/HE detection
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42762 SUBJECT: GRB 251117A: Insight-HXMT/HE detection DATE: 25/11/19 15:10:34 GMT FROM: Yue Wang <m18509381757(a)163.com> Yue Wang, Chen-Wei Wang, Chao Zheng, and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team: At 2025-11-17T12:19:52.500 (T0), Insight-HXMT/HE detected a short-duration GRB 251117A, which is also detected by Fermi/GBM (Fermi GBM Team, GCN #42719), Fermi/LAT (A. Holzmann Airasca et. al., GCN #42729) and SVOM/GRM (Yue Wang et. al., GCN #42731). The Insight-HXMT/HE light curve mainly consists of multiple peaks with a T90 of 2.3 +2.2/-1.1 s. The 1s peak rate, measured from T0-0.05 s, is 1167 cnts/sec. Insight-HXMT/HE detected a total of 1604 counts from this burst. The Insight-HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251117A.png All measurements above are made with the CsI detectors of Insight-HXMT/HE operating in the regular mode with the energy range of about 60-900 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org View this GCN Circular online at https://gcn.nasa.gov/circulars/42762. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40828] GRB 251119A: SVOM trigger sb25111901 is not a GRB
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42761 SUBJECT: GRB 251119A: SVOM trigger sb25111901 is not a GRB DATE: 25/11/19 13:26:53 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> C. Wu (NAOC), K.X. Gong (CHO), M. Brunet (IRAP), D. Turpin, S. Schanne, D. Gotz (CEA), U. Jacob (LUPM), report on behalf of the SVOM mission team: At 2025-11-19T08:47:44 SVOM issued an alert with burst-id: sb25111901. The following circular(s) have been published regarding this event: GCN 42757, with the event labelled as GRB 251119A This event is not a GRB of astrophysical origin. After reprocessing the data with the full telemetry, this trigger is no longer considered as an astrophysical source but is due to coding noise from the Crab in the field of view. We apologize for any inconvenience this may have caused. The Burst Advocate (BA) on shift for this alert is Chao Wu: cwu(a)bao.ac.cn. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42761. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40827] EP251118a: VLT near-infrared observation
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42760 SUBJECT: EP251118a: VLT near-infrared observation DATE: 25/11/19 13:22:26 GMT FROM: muskan.yadav(a)students.uniroma2.eu Muskan Yadav, Yu-Han Yang, Massine El Kabir, Niccolò Passaleva, Nicolás Monsalves (U Rome) on behalf of the ERC BHianca team: We observed the field of EP251118a (Jiang et al., GCN 42749) with the HAWKI imager on the ESO VLT UT4 (Yepun). Observations began at 15.5 hr after the EP/WXT trigger and were carried out at an average airmass of about 1.2 in the J filter. We detect the optical counterpart (Malesani et al., GCN 42751; Belkin et al., GCN 42758) at a preliminary magnitude J ~20.35 AB mag calibrated using nearby stars in the 2MASS Catalogue (Skrutskie et al. 2006) and not corrected for Galactic extinction. We thank the staff at the VLT, for the rapid execution of these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42760. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40826] GRB 251116D: SVOM/GRM observation of a long GRB
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42759 SUBJECT: GRB 251116D: SVOM/GRM observation of a long GRB DATE: 25/11/19 11:43:21 GMT FROM: Xinghao Luo at SVOM/GRN <2952704891(a)qq.com> GRB 251116D: SVOM/GRM observation of a long GRB SVOM/GRM team: Xing-Hao Luo, Chen-Wei Wang, Zheng-Hang Yu, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Marius Brunet (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by GRB 251116D(SVOM trigger reference: sb25111606) at 2025-11-16T19:22:37.000 UTC(T0), which is also detected by AstroSat/CZTI (Harsha K. H. et.al., GCN #42715) , Konus-Wind and Glowbug (C.C. Cheung et.al., GCN #42718). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multi-pulses and a possible bump with a T90 of 45 +3/-21 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251116D.png In addition, the position of this burst, as determined by Glowbug (RA=148.0 , DEC=-37.6, with a raidus of 3.7 der (95% confidence), C.C. Cheung et.al., GCN #42718), is located at about 131 degrees form the SVOM optical axis, which is outside the ECLAIRs field of view. However this burst is seen by ECLAIRs by reflection on the atmosphere. With this localization, the time-averaged spectrum from T0-2 to T0+20 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.52 +0.21/-0.17 and the cutoff energy, parameterized as Epeak, is 498 +294/-139 keV. The event fluence (10-1000keV) in this time interval is (3.31 +0.18/-0.21)E-05 erg/cm^2. The localization of GRB 251116D in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb251116D_amati.png The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM point of contact for this burst is: Xing-Hao Luo (2952704891(a)qq.com) View this GCN Circular online at https://gcn.nasa.gov/circulars/42759. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40825] EP251118a: GOTO optical afterglow detection
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42758 SUBJECT: EP251118a: GOTO optical afterglow detection DATE: 25/11/19 11:15:29 GMT FROM: Sergey Belkin at Monash University <sergey.belkin(a)monash.edu> S. Belkin, M. E. Wortley, D. O'Neill, B. P. Gompertz, G. Ramsay, R. L. C. Starling, K. Ackley, M. Dyer, J. Lyman, K. Ulaczyk, D. Steeghs, D. Galloway, V. Dhillon, P. O'Brien, K. Noysena, R. Kotak, R. Breton, J. Casares, L. Nuttall, B. Godson, T. Killestein, A. Kumar, M. Pursiainen report on behalf of GOTO collaboration: We report on optical observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al 2024) in response to the EP/WXT alert WXT11900480769 (Jiang et al., GCN 42749). Observations covering the position began on 2025-11-19 at 02:58:22 UT (+10.26 hr post trigger) and continued through to 2025-11-19 at 04:30:49 UT (+11.81 hr post trigger). Three epochs were obtained: the first through serendipitous survey coverage (4x45 s) and the second and third through targeted response (4x90 s), all in the GOTO L-band (400-700 nm). Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations. We detect the optical counterpart (Malesani et al., GCN 42751), consistent with the X-ray counterpart (Shi et al., GCN 42754), with L = 20.08 ± 0.21 (AB) on 2025-11-19 at 02:58:22 UT (+10.26 hr). Follow-up L-band images at 03:22:37 UT (+10.67 hr) and 04:30:49 (+11.81 hr) yield L = 20.24 ± 0.17 and 20.17 ± 0.16 (AB), respectively. Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction. GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester, the University of Birmingham, and the Instituto de Astrofisica de Canarias (IAC). View this GCN Circular online at https://gcn.nasa.gov/circulars/42758. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40824] GRB 251119A: SVOM detection of a possible burst
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42757 SUBJECT: GRB 251119A: SVOM detection of a possible burst DATE: 25/11/19 09:26:05 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> C. Wu (NAOC), K.X. Gong (CHO), D. Turpin, S. Schanne, D. Gotz (CEA), U. Jacob (LUPM) report on behalf of the SVOM mission team: At 2025-11-19T08:47:44 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251119A (SVOM burst-id sb25111901). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was only detected by the Count-Rate Trigger (CRT), which produced a sequence of 3 alerts. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 7.89 in the [5-8] keV energy band over a time window of 20.40 seconds starting at 2025-11-19T08:47:23 (Tb). The localization of the best alert is R.A., Dec. 84.4289, 12.2431 degrees: R.A. (J2000) = 5h37m42.93s Dec. (J2000) = 12d14m35.17s with a 90% confidence level (C.L.) radius of 9.96 arcmin (including systematic error of 2 arcmin added in quadrature). We notice that the Crab is located near the border of the field of view and about 9.8 degrees away from the burst’s position with a SNR of 9.0 (similar to the burst’s SNR) in the sky image. SVOM slewed to the burst position. SVOM/MXT began observing the field at 08:51:08 UTC, 206 seconds after T0. Using onboard processed data, no source was detected in 225 seconds. The SVOM/MXT team is waiting for the full dataset to detect and localise the possible SVOM/MXT counterpart. VT began observing the field after the slew. The analysis of the data will be published in a future circular. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Chao Wu: cwu(a)bao.ac.cn. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42757. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40823] EP251118a: NOT spectroscopic redshift of z = 1.216
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42756 SUBJECT: EP251118a: NOT spectroscopic redshift of z = 1.216 DATE: 25/11/19 09:17:33 GMT FROM: J. An <jiean0813(a)foxmail.com> J. An (NAOC), D. B. Malesani (DAWN/NBI and Radboud), L.B. He, D. Xu, X.Liu (NAOC), G. Corcoran (UCD), L. Cotter (UCD), A. J. Levan (Radboud and Warwick), P. G. Jonker (Radboud), L. Fuglsang (NOT), report on behalf of a large collaboration: We observed the optical afterglow (Malesani et al., GCN 42751) of EP251118a (Jiang et al., GCN 42749) with the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. A spectrum using grism #4 was secured starting on 2025 Nov 19.19 UT (11.9 h after the GRB). A total of 4 spectra of 1200 s each were obtained, covering the wavelength range 3500-9600 AA. Preliminary reduction of the stacked spectrum shows a clear continuum down to at least 3700 AA. The lack of a Ly-alpha feature in the spectrum sets a redshift limit z < 2. A few narrow absorption features are detected, which we attribute to the Mg II doublet and several Fe II lines (2600, 2586, 2344), all at a common redshift of z = 1.216. We suggest this is the redshift of EP251118a. View this GCN Circular online at https://gcn.nasa.gov/circulars/42756. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40822] EP251118a: Global MASTER-Net observations report
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42755 SUBJECT: EP251118a: Global MASTER-Net observations report DATE: 25/11/19 08:27:23 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) was pointed to the EP251118a ( EP Team et al., GCN 42749) errorbox 12817 sec after notice time and 54875 sec after trigger time at 2025-11-19 07:57:04 UT, with upper limit up to 20.2 mag. The observations began at zenith distance = 44 deg. The sun altitude is -17.5 deg. The galactic latitude b = 23 deg., longitude l = 213 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3046754 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 54905 | 2025-11-19 07:57:04 | MASTER-OAFA | (08h 12m 31.85s , +10d 55m 21.3s) | C | 60 | 20.2 | 54982 | 2025-11-19 07:58:20 | MASTER-OAFA | (08h 12m 38.49s , +10d 54m 18.7s) | C | 60 | 20.0 | 55059 | 2025-11-19 07:59:38 | MASTER-OAFA | (08h 12m 32.20s , +10d 53m 14.4s) | C | 60 | 20.0 | 55137 | 2025-11-19 08:00:55 | MASTER-OAFA | (08h 12m 37.33s , +10d 53m 29.6s) | C | 60 | 20.1 | 55223 | 2025-11-19 08:02:21 | MASTER-OAFA | (08h 12m 33.38s , +10d 54m 50.5s) | C | 60 | 20.2 | 55301 | 2025-11-19 08:03:39 | MASTER-OAFA | (08h 12m 32.94s , +10d 53m 07.3s) | C | 60 | 20.1 | 55408 | 2025-11-19 08:04:56 | MASTER-OAFA | (08h 12m 34.44s , +10d 54m 29.2s) | C | 120 | 20.0 | 55544 | 2025-11-19 08:07:13 | MASTER-OAFA | (08h 12m 28.30s , +10d 53m 45.7s) | C | 120 | 20.1 | 55681 | 2025-11-19 08:09:30 | MASTER-OAFA | (08h 12m 28.13s , +10d 54m 37.0s) | C | 120 | 20.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42755. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40821] EP251118a: preliminary result of EP-FXT follow-up observation
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42754 SUBJECT: EP251118a: preliminary result of EP-FXT follow-up observation DATE: 25/11/19 07:36:46 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> R. Shi, Q. J. Huang, D. F. Hu (PMO, CAS), F. F. Song (YNAO, CAS), S. Q. Jiang (NAO, CAS), Q. C. Liu (THU), C. C. Jin (NAO, CAS) report on behalf of the Einstein Probe team: The Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) performed one ToO observation for EP251118a, starting at 2025-11-19T04:02:14 (UTC). Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 123.1677 deg, DEC = 10.9364 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). The position is consistent with the optical counterpart reported before (Malesani et al. GCN [42751](https://gcn.nasa.gov/circulars/42751)) with a seperation of 14.75 arcsec. Further information will be updated when the telemetry data is received. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/42754. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40820] LAT GRB251118.86: Global MASTER-Net observations report
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42753 SUBJECT: LAT GRB251118.86: Global MASTER-Net observations report DATE: 25/11/19 06:11:24 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) was pointed to the LAT GRB251118.86 (trigger No 785190695,10h 40m 19.92s , -34d 34m 33.6s, R=0.173833) errorbox 972 sec after notice time and 28422 sec after trigger time at 2025-11-19 04:25:12 UT, with upper limit up to 19.1 mag. The observations began at zenith distance = 83 deg. The sun altitude is -39.6 deg. The galactic latitude b = 21 deg., longitude l = 275 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3046739 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 28452 | 2025-11-19 04:25:12 | MASTER-OAFA | (10h 40m 39.45s , -34d 39m 40.3s) | C | 60 | 13.8 | 28518 | 2025-11-19 04:26:18 | MASTER-OAFA | (10h 40m 39.40s , -34d 39m 38.3s) | C | 60 | 14.7 | 28584 | 2025-11-19 04:27:23 | MASTER-OAFA | (10h 40m 39.38s , -34d 39m 35.5s) | C | 60 | 15.0 | 28649 | 2025-11-19 04:28:29 | MASTER-OAFA | (10h 40m 39.39s , -34d 39m 32.7s) | C | 60 | 15.4 | 28715 | 2025-11-19 04:29:35 | MASTER-OAFA | (10h 40m 39.27s , -34d 39m 30.8s) | C | 60 | 15.7 | 28780 | 2025-11-19 04:30:40 | MASTER-OAFA | (10h 40m 39.19s , -34d 39m 28.4s) | C | 60 | 16.1 | 28846 | 2025-11-19 04:31:46 | MASTER-OAFA | (10h 40m 39.06s , -34d 39m 25.8s) | C | 60 | 16.2 | 28913 | 2025-11-19 04:32:52 | MASTER-OAFA | (10h 40m 38.91s , -34d 39m 23.6s) | C | 60 | 16.5 | 28978 | 2025-11-19 04:33:58 | MASTER-OAFA | (10h 40m 38.80s , -34d 39m 21.9s) | C | 60 | 16.5 | 29044 | 2025-11-19 04:35:03 | MASTER-OAFA | (10h 40m 38.68s , -34d 39m 19.9s) | C | 60 | 16.7 | 29110 | 2025-11-19 04:36:10 | MASTER-OAFA | (10h 40m 38.57s , -34d 39m 17.8s) | C | 60 | 17.0 | 29175 | 2025-11-19 04:37:15 | MASTER-OAFA | (10h 40m 38.40s , -34d 39m 16.0s) | C | 60 | 17.1 | 29241 | 2025-11-19 04:38:20 | MASTER-OAFA | (10h 40m 38.33s , -34d 39m 13.9s) | C | 60 | 17.3 | 29307 | 2025-11-19 04:39:26 | MASTER-OAFA | (10h 40m 38.21s , -34d 39m 12.1s) | C | 60 | 17.3 | 29372 | 2025-11-19 04:40:32 | MASTER-OAFA | (10h 40m 38.07s , -34d 39m 10.1s) | C | 60 | 17.3 | 29438 | 2025-11-19 04:41:38 | MASTER-OAFA | (10h 40m 37.93s , -34d 39m 08.0s) | C | 60 | 17.3 | 29504 | 2025-11-19 04:42:44 | MASTER-OAFA | (10h 40m 37.75s , -34d 39m 06.1s) | C | 60 | 17.6 | 29570 | 2025-11-19 04:43:49 | MASTER-OAFA | (10h 40m 37.59s , -34d 39m 04.2s) | C | 60 | 17.6 | 29635 | 2025-11-19 04:44:55 | MASTER-OAFA | (10h 40m 37.45s , -34d 39m 02.1s) | C | 60 | 17.6 | 29701 | 2025-11-19 04:46:01 | MASTER-OAFA | (10h 40m 37.31s , -34d 39m 00.4s) | C | 60 | 17.9 | 29767 | 2025-11-19 04:47:06 | MASTER-OAFA | (10h 40m 37.14s , -34d 38m 58.3s) | C | 60 | 17.9 | 29832 | 2025-11-19 04:48:12 | MASTER-OAFA | (10h 40m 36.96s , -34d 38m 56.4s) | C | 60 | 17.9 | 29899 | 2025-11-19 04:49:18 | MASTER-OAFA | (10h 40m 36.87s , -34d 38m 54.3s) | C | 60 | 17.9 | 29965 | 2025-11-19 04:50:24 | MASTER-OAFA | (10h 40m 36.75s , -34d 38m 52.3s) | C | 60 | 18.0 | 30030 | 2025-11-19 04:51:30 | MASTER-OAFA | (10h 40m 36.61s , -34d 38m 50.3s) | C | 60 | 18.0 | 30096 | 2025-11-19 04:52:36 | MASTER-OAFA | (10h 40m 36.50s , -34d 38m 48.1s) | C | 60 | 18.1 | 30162 | 2025-11-19 04:53:41 | MASTER-OAFA | (10h 40m 36.37s , -34d 38m 46.0s) | C | 60 | 18.2 | 30227 | 2025-11-19 04:54:47 | MASTER-OAFA | (10h 40m 36.23s , -34d 38m 44.6s) | C | 60 | 18.2 | 30293 | 2025-11-19 04:55:53 | MASTER-OAFA | (10h 40m 36.14s , -34d 38m 42.1s) | C | 60 | 18.3 | 30359 | 2025-11-19 04:56:58 | MASTER-OAFA | (10h 40m 36.02s , -34d 38m 40.1s) | C | 60 | 18.3 | 30424 | 2025-11-19 04:58:04 | MASTER-OAFA | (10h 40m 35.89s , -34d 38m 38.1s) | C | 60 | 18.4 | 30491 | 2025-11-19 04:59:10 | MASTER-OAFA | (10h 40m 35.75s , -34d 38m 36.2s) | C | 60 | 18.5 | 30556 | 2025-11-19 05:00:16 | MASTER-OAFA | (10h 40m 35.66s , -34d 38m 33.8s) | C | 60 | 18.5 | 30621 | 2025-11-19 05:01:21 | MASTER-OAFA | (10h 40m 35.53s , -34d 38m 31.4s) | C | 60 | 18.5 | 30687 | 2025-11-19 05:02:27 | MASTER-OAFA | (10h 40m 35.40s , -34d 38m 29.6s) | C | 60 | 18.6 | 30753 | 2025-11-19 05:03:32 | MASTER-OAFA | (10h 40m 35.26s , -34d 38m 27.7s) | C | 60 | 18.6 | 30818 | 2025-11-19 05:04:38 | MASTER-OAFA | (10h 40m 35.17s , -34d 38m 25.6s) | C | 60 | 18.6 | 30885 | 2025-11-19 05:05:44 | MASTER-OAFA | (10h 40m 35.05s , -34d 38m 23.5s) | C | 60 | 18.7 | 30950 | 2025-11-19 05:06:50 | MASTER-OAFA | (10h 40m 34.89s , -34d 38m 21.4s) | C | 60 | 18.7 | 31016 | 2025-11-19 05:07:55 | MASTER-OAFA | (10h 40m 34.75s , -34d 38m 19.4s) | C | 60 | 18.7 | 31082 | 2025-11-19 05:09:02 | MASTER-OAFA | (10h 40m 34.60s , -34d 38m 17.2s) | C | 60 | 18.7 | 31147 | 2025-11-19 05:10:07 | MASTER-OAFA | (10h 40m 34.49s , -34d 38m 15.4s) | C | 60 | 18.8 | 31213 | 2025-11-19 05:11:13 | MASTER-OAFA | (10h 40m 34.36s , -34d 38m 13.2s) | C | 60 | 18.8 | 31279 | 2025-11-19 05:12:19 | MASTER-OAFA | (10h 40m 34.23s , -34d 38m 11.3s) | C | 60 | 18.8 | 31345 | 2025-11-19 05:13:24 | MASTER-OAFA | (10h 40m 34.10s , -34d 38m 09.0s) | C | 60 | 18.8 | 31410 | 2025-11-19 05:14:30 | MASTER-OAFA | (10h 40m 33.98s , -34d 38m 07.1s) | C | 60 | 18.9 | 31476 | 2025-11-19 05:15:36 | MASTER-OAFA | (10h 40m 33.86s , -34d 38m 04.6s) | C | 60 | 18.9 | 31542 | 2025-11-19 05:16:41 | MASTER-OAFA | (10h 40m 33.76s , -34d 38m 02.4s) | C | 60 | 18.9 | 31607 | 2025-11-19 05:17:47 | MASTER-OAFA | (10h 40m 33.66s , -34d 38m 00.3s) | C | 60 | 18.9 | 31673 | 2025-11-19 05:18:52 | MASTER-OAFA | (10h 40m 33.53s , -34d 37m 58.3s) | C | 60 | 18.9 | 31738 | 2025-11-19 05:19:58 | MASTER-OAFA | (10h 40m 33.38s , -34d 37m 56.0s) | C | 60 | 18.9 | 31804 | 2025-11-19 05:21:03 | MASTER-OAFA | (10h 40m 33.26s , -34d 37m 53.7s) | C | 60 | 18.9 | 31870 | 2025-11-19 05:22:10 | MASTER-OAFA | (10h 40m 33.13s , -34d 37m 51.8s) | C | 60 | 18.9 | 31936 | 2025-11-19 05:23:16 | MASTER-OAFA | (10h 40m 33.01s , -34d 37m 49.6s) | C | 60 | 18.9 | 32002 | 2025-11-19 05:24:21 | MASTER-OAFA | (10h 40m 32.90s , -34d 37m 47.5s) | C | 60 | 18.9 | 32068 | 2025-11-19 05:25:27 | MASTER-OAFA | (10h 40m 32.77s , -34d 37m 45.1s) | C | 60 | 19.0 | 32133 | 2025-11-19 05:26:33 | MASTER-OAFA | (10h 40m 32.64s , -34d 37m 42.8s) | C | 60 | 18.9 | 32198 | 2025-11-19 05:27:38 | MASTER-OAFA | (10h 40m 32.50s , -34d 37m 40.9s) | C | 60 | 18.9 | 32265 | 2025-11-19 05:28:44 | MASTER-OAFA | (10h 40m 32.41s , -34d 37m 38.8s) | C | 60 | 18.9 | 32330 | 2025-11-19 05:29:50 | MASTER-OAFA | (10h 40m 32.29s , -34d 37m 36.8s) | C | 60 | 19.0 | 32396 | 2025-11-19 05:30:55 | MASTER-OAFA | (10h 40m 32.17s , -34d 37m 34.7s) | C | 60 | 19.0 | 32462 | 2025-11-19 05:32:01 | MASTER-OAFA | (10h 40m 32.05s , -34d 37m 32.6s) | C | 60 | 19.0 | 32527 | 2025-11-19 05:33:07 | MASTER-OAFA | (10h 40m 31.94s , -34d 37m 30.3s) | C | 60 | 19.0 | 32592 | 2025-11-19 05:34:12 | MASTER-OAFA | (10h 40m 31.81s , -34d 37m 28.3s) | C | 60 | 19.0 | 32659 | 2025-11-19 05:35:18 | MASTER-OAFA | (10h 40m 31.72s , -34d 37m 26.0s) | C | 60 | 19.0 | 32724 | 2025-11-19 05:36:24 | MASTER-OAFA | (10h 40m 31.62s , -34d 37m 24.0s) | C | 60 | 19.0 | 32790 | 2025-11-19 05:37:29 | MASTER-OAFA | (10h 40m 31.49s , -34d 37m 22.0s) | C | 60 | 19.0 | 32856 | 2025-11-19 05:38:36 | MASTER-OAFA | (10h 40m 31.39s , -34d 37m 19.8s) | C | 60 | 19.0 | 32922 | 2025-11-19 05:39:41 | MASTER-OAFA | (10h 40m 31.28s , -34d 37m 17.6s) | C | 60 | 19.0 | 32987 | 2025-11-19 05:40:47 | MASTER-OAFA | (10h 40m 31.23s , -34d 37m 15.6s) | C | 60 | 19.0 | 33053 | 2025-11-19 05:41:53 | MASTER-OAFA | (10h 40m 31.08s , -34d 37m 13.4s) | C | 60 | 19.1 | 33118 | 2025-11-19 05:42:58 | MASTER-OAFA | (10h 40m 31.04s , -34d 37m 11.1s) | C | 60 | 19.0 | 33184 | 2025-11-19 05:44:03 | MASTER-OAFA | (10h 40m 30.92s , -34d 37m 09.5s) | C | 60 | 19.0 | 33250 | 2025-11-19 05:45:10 | MASTER-OAFA | (10h 40m 30.85s , -34d 37m 07.0s) | C | 60 | 19.0 | 33316 | 2025-11-19 05:46:15 | MASTER-OAFA | (10h 40m 30.75s , -34d 37m 05.0s) | C | 60 | 19.0 | 33381 | 2025-11-19 05:47:21 | MASTER-OAFA | (10h 40m 30.69s , -34d 37m 03.0s) | C | 60 | 19.0 | 33448 | 2025-11-19 05:48:28 | MASTER-OAFA | (10h 40m 30.59s , -34d 37m 00.4s) | C | 60 | 19.1 | 33513 | 2025-11-19 05:49:33 | MASTER-OAFA | (10h 40m 30.50s , -34d 36m 58.5s) | C | 60 | 19.0 | 33579 | 2025-11-19 05:50:38 | MASTER-OAFA | (10h 40m 30.45s , -34d 36m 56.3s) | C | 60 | 19.1 | 33645 | 2025-11-19 05:51:44 | MASTER-OAFA | (10h 40m 30.39s , -34d 36m 54.0s) | C | 60 | 19.0 | 33710 | 2025-11-19 05:52:50 | MASTER-OAFA | (10h 40m 30.29s , -34d 36m 51.8s) | C | 60 | 19.0 | 33776 | 2025-11-19 05:53:56 | MASTER-OAFA | (10h 40m 30.20s , -34d 36m 50.0s) | C | 60 | 19.0 | 33842 | 2025-11-19 05:55:02 | MASTER-OAFA | (10h 40m 30.14s , -34d 36m 47.5s) | C | 60 | 19.0 | 33908 | 2025-11-19 05:56:08 | MASTER-OAFA | (10h 40m 30.05s , -34d 36m 45.1s) | C | 60 | 19.1 | 33973 | 2025-11-19 05:57:13 | MASTER-OAFA | (10h 40m 29.97s , -34d 36m 43.0s) | C | 60 | 19.0 | 34039 | 2025-11-19 05:58:19 | MASTER-OAFA | (10h 40m 29.87s , -34d 36m 40.9s) | C | 60 | 19.0 | 34104 | 2025-11-19 05:59:24 | MASTER-OAFA | (10h 40m 29.79s , -34d 36m 38.4s) | C | 60 | 19.0 | 34169 | 2025-11-19 06:00:29 | MASTER-OAFA | (10h 40m 29.72s , -34d 36m 36.7s) | C | 60 | 19.0 | 34236 | 2025-11-19 06:01:35 | MASTER-OAFA | (10h 40m 29.62s , -34d 36m 34.4s) | C | 60 | 19.0 | 34302 | 2025-11-19 06:02:41 | MASTER-OAFA | (10h 40m 29.57s , -34d 36m 32.4s) | C | 60 | 19.0 | 34367 | 2025-11-19 06:03:47 | MASTER-OAFA | (10h 40m 29.51s , -34d 36m 29.9s) | C | 60 | 19.0 | 34433 | 2025-11-19 06:04:53 | MASTER-OAFA | (10h 40m 29.42s , -34d 36m 27.6s) | C | 60 | 19.0 | 34499 | 2025-11-19 06:05:58 | MASTER-OAFA | (10h 40m 29.36s , -34d 36m 25.3s) | C | 60 | 19.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42753. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40819] GRB 251118A: Fermi-LAT detection
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42752 SUBJECT: GRB 251118A: Fermi-LAT detection DATE: 25/11/19 05:39:12 GMT FROM: Rahul Gupta at NASA GSFC <rahul.gupta(a)nasa.gov> R. Gupta (NASA GSFC) and T. Khalil (Univ. of Johannesburg) report on behalf of the Fermi-LAT Collaboration: On November 18 2025, Fermi-LAT detected high-energy emission from GRB 251118A, which was also detected by Fermi-GBM (trigger 785190695 / 251118855, GCN 42743). The best LAT on-ground location is found to be: RA, Dec = 160.08, -34.58 (J2000) with an error radius of 0.17 deg (90 % containment, statistical error only). This was 69 deg from the LAT boresight at the time of the GBM trigger (T0 = 20:31:30.09 UT). The data from the Fermi-LAT shows a significant increase in the event rate that is spatially and temporally correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval 0 - 1.5 ks after the GBM trigger is (1.8 ± 0.7) E-6 ph/cm2/s. The estimated photon index above 100 MeV is -1.8 ± 0.3. The highest-energy photon is a 6.8 GeV event which is observed ~1400 seconds after the GBM trigger. A Swift ToO has been approved for this burst. The Fermi-LAT point of contact for this burst is Aldana Holzmann Airasca (a.holzmannairasca(a)unitn.it) The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. View this GCN Circular online at https://gcn.nasa.gov/circulars/42752. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40818] EP251118a: NOT candidate optical counterpart
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42751 SUBJECT: EP251118a: NOT candidate optical counterpart DATE: 25/11/19 05:20:57 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani(a)nbi.ku.dk> D. B. Malesani (DAWN/NBI and Radboud), G. Corcoran (UCD), L. Cotter (UCD), J. An, Z.P. Zhu, D. Xu (NAOC), P. G. Jonker (Radboud), L. Fuglsang (NOT), report on behalf of a larger collaboration: We observed the field of the transient event EP251118a (Jiang et al., GCN 42749) detected by the Einstein Probe Wide-field X-ray Telescope (EP WXT), using the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations were obtained in the r (3x300 s) and z (5x200 s) bands, starting on 2025-11-19 at 03:55:38 UT (11.22 hr after the EP/WXT trigger). In our first r-band exposure, within the WXT uncertainty region, we detect a source significantly brighter than in the archival images from the Legacy Survey. This object has coordinates: RA(J2000): 08:12:39.4 Dec(J2000): +10:56:18.88 with an uncertainty of 0.5" in both RA and Dec. In the NOT image, we measure an AB magnitude of r = 20.52+/-0.04, calibrated against the Pan-STARRS catalog and not corrected for Galactic extinction. At this location, a source can be marginally seen in the deeper Legacy Source images, with an AB magnitude of r = 24.18 +/- 0.26. The source seen in the NOT images is a candidate optical afterglow of EP251118a, and the archival counterpart in the Legacy Survey is its candidate host galaxy. Further multi-wavelength observations are encouraged to confirm the nature of this object. View this GCN Circular online at https://gcn.nasa.gov/circulars/42751. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40817] EP251118a: NOT candidate optical counterpart
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42751 SUBJECT: EP251118a: NOT candidate optical counterpart DATE: 25/11/19 05:20:57 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani(a)nbi.ku.dk> D. B. Malesani (DAWN/NBI and Radboud), G. Corcoran (UCD), L. Cotter (UCD), J. An, Z.P. Zhu, D. Xu (NAOC), P. G. Jonker (Radboud), L. Fuglsang (NOT), report on behalf of a larger collaboration: We observed the field of the transient event EP251118a (Jiang et al., GCN 42749) detected by the Einstein Probe Wide-field X-ray Telescope (EP WXT), using the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations were obtained in the r (3x300 s) and z (5x200 s) bands, starting on 2025-11-19 at 03:55:38 UT (11.22 hr after the EP/WXT trigger). In our first r-band exposure, within the WXT uncertainty region, we detect a source significantly brighter than in the archival images from the Legacy Survey. This object has coordinates: RA(J2000): 08:12:39.4 Dec(J2000): +10:56:18.88 with an uncertainty of 0.5" in both RA and Dec. In the NOT image, we measure an AB magnitude of r = 20.52+/-0.04, calibrated against the Pan-STARRS catalog and not corrected for Galactic extinction. At this location, a source can be marginally seen in the deeper Legacy Source images, with an AB magnitude of r = 24.18 +/- 0.26. The source seen in the NOT images is a candidate optical afterglow of EP251118a, and the archival counterpart in the Legacy Survey is its candidate host galaxy. Further multi-wavelength observations are encouraged to confirm the nature of this object. View this GCN Circular online at https://gcn.nasa.gov/circulars/42751. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40816] GRB 251118A: Swift ToO observations
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42750 SUBJECT: GRB 251118A: Swift ToO observations DATE: 25/11/19 05:10:33 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a ToO observation of the Fermi/LAT-detected event GRB 251118A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021890 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the Fermi/LAT event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42750. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40815] EP251118a: Einstein Probe detected of a fast X-ray transient
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42749 SUBJECT: EP251118a: Einstein Probe detected of a fast X-ray transient DATE: 25/11/19 04:22:00 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> S. Q. Jiang (NAO, CAS), Q. C. Liu (THU), D. F. Hu, R. Shi, Q. J. Huang (PMO, CAS), F. F. Song (YNAO, CAS), C. C. Jin (NAO, CAS) report on behalf of the Einstein Probe team: We report on the detection of a fast X-ray transient EP251118a by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The transient did not trigger the WXT onboard unit. A GCN Notice was sent manually (trigger ID: 11900480769). The WXT light curve started at 2025-11-18T16:42:29 (UTC). The position of the source is R.A. = 123.160 deg, DEC = 10.952 deg (J2000) with an uncertainty of 1.87 arcmin (radius, 90% C.L. statistical and systematic). The transient event has a precursor-like signature lasted about 42 seconds followed by a main burst lasting at least 79 seconds. After that, the observation ended, resulting in no further data. The average 0.5-4.0 keV spectrum can be fitted with an absorbed powerlaw model, with free nH of 2.26 (-0.26/+0.27) x 10^21 cm^-2 and a photon index of 1.32 (-0.08/+0.08). The unabsorbed average 0.5-4.0 keV flux is estimated to be 2.50 (-0.08/+0.08) x 10^-8 erg/s/cm2. The peak flux reaches around 1 x 10^-7 erg/s/cm2. The uncertainties are at the 90% confidence level for the above parameters. Further FXT observations are scheduled. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/42749. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40814] Fermi GRB 251118B: Global MASTER-Net observations report
by GCN Circulars 19 Nov '25

19 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42748 SUBJECT: Fermi GRB 251118B: Global MASTER-Net observations report DATE: 25/11/19 02:45:37 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Kislovodsk robotic telescope [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 251118B ( Fermi GBM team, GCN 42747) errorbox 14082 sec after notice time and 14113 sec after trigger time at 2025-11-19 02:35:18 UT, with upper limit up to 13.8 mag. Observations started at twilight. The observations began at zenith distance = 73 deg. The sun altitude is -16.8 deg. The galactic latitude b = 46 deg., longitude l = 45 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3046507 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 14144 | 2025-11-19 02:35:18 | MASTER-Kislovodsk | (15h 26m 28.11s , +27d 50m 43.7s) | C | 60 | 13.2 | 14144 | 2025-11-19 02:35:18 | MASTER-Kislovodsk | (15h 30m 55.71s , +27d 27m 25.3s) | C | 60 | 13.8 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42748. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40813] GRB 251118B: Fermi GBM Final Real-time Localization
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42747 SUBJECT: GRB 251118B: Fermi GBM Final Real-time Localization DATE: 25/11/18 22:50:34 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 22:40:05 UT on 18 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251118B (trigger 785198410.034588 / 251118945). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 242.6, Dec = 26.9 (J2000 degrees, equivalent to J2000 16h 10m, 26d 53'), with a statistical uncertainty of 10.0 degrees. The angle from the Fermi LAT boresight is 81.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118945/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118945/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118945/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42747. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40812] LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42746 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations DATE: 25/11/18 22:20:54 GMT FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung(a)nrl.navy.mil> M. Kerr, C.C. Cheung, R. Woolf, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The compact binary merger candidate S251112cm (event time, T0 = 2025-11-12T15:19:22.360 UTC) was identified in LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data (GCN 42690). The Glowbug gamma-ray instrument [1,2,3] observed much of the sky to which a high probability for the candidate origin was assigned. Glowbug has an all-sky field-of-view limited only by earth occultation and large-scale structures on the International Space Station (ISS). At T0, the Glowbug boresight was pointed towards R.A., Dec. = 92, 22 deg. We examined three high-probability regions in the contours with positions R.A., Dec. = 346, -13 deg; 173, 43 deg; and 149, 6.5 deg, which were at zenith angles of 110 deg., 68 deg., and 57 deg., respectively, all nominally above the limb of the earth. Positions at lower zenith angles, however, are more likely to be obstructed by ISS structure. Using 50-2000 keV data and two representative (normal and hard spectrum) GRB templates from [4], we searched for transient gamma-ray signals using maximum likelihood methods and found no plausible counterpart up to 30s before or after T0. We determined 3-sigma upper limits on the flux for a GRB at the three trial positions by selecting data centered on T0 and integrating the posterior probability to determine the flux beyond which the tail probability is 0.27%. For various timescales and the two GRB spectral templates, the range of limits (over the three positions) in units of 1e-7 erg/cm2/s are: Timescale Normal Hard ------------------------------------ 0.128 s: 1.4-2.8 3.0-6.0 1.024 s: 0.8-1.0 1.5-2.0 8.192 s: 0.2-0.4 0.4-1.0 These results do not account for scattering or occultation by structures on the ISS. We do not report results for an assumed soft spectrum due to a likely increase in the low-energy threshold of Glowbug due to accumulated radiation exposure. The Glowbug sky coverage is complementary to that obtained by Fermi/GBM (GCN 42655). Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 [4] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv:1909.03006 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42746. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40811] GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42745 SUBJECT: GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855) DATE: 25/11/18 20:57:48 GMT FROM: Jochen Greiner at MPE <jcgrog(a)mpe.mpg.de> T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report: The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 785190695 at 20:31:30 on 18 Nov. 2025 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60). The best-fit position is: RA(2000.0) = 160.0 deg Decl.(2000.0) = -34.9 deg The 1 sigma statistical error radius is 2.0 deg. We estimate an additional systematic error of 2 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB251118855/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB251118855/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB251118855/json View this GCN Circular online at https://gcn.nasa.gov/circulars/42745. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40810] GRB 251117A: FTW Observations of Swift candidate X-ray sources
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42744 SUBJECT: GRB 251117A: FTW Observations of Swift candidate X-ray sources DATE: 25/11/18 20:56:30 GMT FROM: Malte Busmann at Ludwig-Maximilians-Universität München <m.busmann(a)physik.lmu.de> Malte Busmann (LMU), Xander J. Hall (CMU), Brendan O'Connor (CMU), Daniel Gruen (LMU), and Antonella Palmese (CMU) report: We observed the candidate Swift X-ray sources GRB 251117a_X6 and X7 (Evans et al., GCN 42730), as potential counterparts to GRB 251117A (Fermi GBM team, GCN 42719; Airasca et al., GCN 42729; Wang et al., GCN 42731; DeLaunay et al., GCN 42732; Arya et al., GCN 42740) with the Three Channel Imager (3KK) at the Fraunhofer Telescope at Wendelstein Observatory (FTW) in the r, i and J band simultaneously for 10 x 180 s starting at 2025-11-18T17:36:17 UT (1.22 days after the trigger). We performed difference imaging with archival images from Legacy Survey and do not detect any new sources down to r > 23.9 AB mag (3 sigma). The magnitudes are calibrated against the PS1 catalog and not corrected for Galactic extinction. We thank Michael Schmidt from the Wendelstein Observatory for obtaining these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42744. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40809] GRB 251118A: Fermi GBM Final Real-time Localization
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42743 SUBJECT: GRB 251118A: Fermi GBM Final Real-time Localization DATE: 25/11/18 20:42:00 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 20:31:30 UT on 18 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251118A (trigger 785190695.089648 / 251118855). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 160.4, Dec = -36.5 (J2000 degrees, equivalent to J2000 10h 41m, -36d 30'), with a statistical uncertainty of 1.0 degrees. The angle from the Fermi LAT boresight is 66.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251118855/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42743. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40808] GRB 251116C: SVOM/ECLAIRs refined analysis
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42742 SUBJECT: GRB 251116C: SVOM/ECLAIRs refined analysis DATE: 25/11/18 18:41:49 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> M. Brunet, O. Godet (IRAP), W. Xie (NAOC), M. Pillas (IAP), M.G. Bernardini (INAF-OAB, LUPM), Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of GRB 251116C (SVOM burst-id sb25111605, GCN 42703) detected at T0 = 2025-11-16T15:57:41, which was also detected by Swift/BAT (GCN 42726). The burst that triggered ECLAIRs consists of a single peak lightcurve, lasting about 60 s in the 4-120 keV energy band. We note that the burst occurred close to the Earth limb and that it was quickly hidden behind the Earth after the trigger so that part of the emission might have been missed by ECLAIRs. The time-averaged spectrum from T0-15 s to T0+39 s in the 5-120 keV energy range is best fitted by a power-law model with a photon index of 1.95 +/-0.10. With this model, the total 4-120 keV fluence is (1.2 +/-0.1) e-06 erg/cm^2. Given the value of the photon index, the peak energy may be below 5keV, which would classify this GRB as an X-Ray Flash. All the quoted errors are at the 68% confidence level. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs point of contact for this burst is: Marius Brunet (IRAP) (marius.brunet at irap.omp.eu) View this GCN Circular online at https://gcn.nasa.gov/circulars/42742. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40807] GRB 251116C: SVOM/ECLAIRs refined analysis
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42742 SUBJECT: GRB 251116C: SVOM/ECLAIRs refined analysis DATE: 25/11/18 18:41:49 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> M. Brunet, O. Godet (IRAP), W. Xie (NAOC), M. Pillas (IAP), M.G. Bernardini (INAF-OAB, LUPM), Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of GRB 251116C (SVOM burst-id sb25111605, GCN 42703) detected at T0 = 2025-11-16T15:57:41, which was also detected by Swift/BAT (GCN 42726). The burst that triggered ECLAIRs consists of a single peak lightcurve, lasting about 60 s in the 4-120 keV energy band. We note that the burst occurred close to the Earth limb and that it was quickly hidden behind the Earth after the trigger so that part of the emission might have been missed by ECLAIRs. The time-averaged spectrum from T0-15 s to T0+39 s in the 5-120 keV energy range is best fitted by a power-law model with a photon index of 1.95 +/-0.10. With this model, the total 4-120 keV fluence is (1.2 +/-0.1) e-06 erg/cm^2. All the quoted errors are at the 68% confidence level. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs point of contact for this burst is: Marius Brunet (IRAP) (marius.brunet at irap.omp.eu) View this GCN Circular online at https://gcn.nasa.gov/circulars/42742. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40806] GRB 251116B: SVOM/ECLAIRs refined analysis
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42741 SUBJECT: GRB 251116B: SVOM/ECLAIRs refined analysis DATE: 25/11/18 18:39:14 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> M. Brunet, O. Godet (IRAP), M. Pillas (IAP), M.G. Bernardini (INAF-OAB, LUPM), Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of GRB 251116B (SVOM burst-id sb25111604, GCN 42702) detected at T0 = 2025-11-16T15:32:36. The burst that triggered ECLAIRs consists of a single peak lightcurve, lasting about 10 s in the 4-120 keV energy band. The time-averaged spectrum from T0-10 s to T0+0.25s in the 5-120 keV energy range is best fitted by a power-law model with a photon index of 1.49 +/-0.28. With this model, the total 4-120 keV fluence is (3.2 +0.2/-1.7)e-07 erg/cm^2. All the quoted errors are at the 68% confidence level. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs point of contact for this burst is: Marius Brunet (IRAP) (marius.brunet at irap.omp.eu) View this GCN Circular online at https://gcn.nasa.gov/circulars/42741. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40805] GRB 251117A: AstroSat CZTI detection
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42740 SUBJECT: GRB 251117A: AstroSat CZTI detection DATE: 25/11/18 16:09:35 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> A. Arya (IITB), A. Goyal (IITB), S. Salunke (IUCAA), M. Tembhurnikar (IUCAA), Harsha K. H. (IUCAA), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a short GRB 251117A which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 42719), Fermi LAT (Airasca et. al., GCN Circ. 42729), SVOM/GRM (Wang et. al., GCN Circ. 42731), and Swift BAT-GUANO (DeLaunay et. al., GCN Circ. 42732). The source was clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-11-17 12:19:52.47 UTC. The measured peak count rate associated with the burst is 424 (+67, -72) counts/s above the background in the combined data of all quadrants, with a total of 561 (+156, -178) counts. The local mean background count rate was 1268 (+11, -12) counts/s. Due to the intrinsic 1 s binning of veto data, we cannot reliably estimate a T90 from it. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/42740. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40804] GRB 251114B: Insight-HXMT/HE detection
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42739 SUBJECT: GRB 251114B: Insight-HXMT/HE detection DATE: 25/11/18 15:58:27 GMT FROM: zhangjinpeng(a)ihep.ac.cn Jin-Peng Zhang, Chen-Wei Wang, Chao Zheng, and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team: At 2025-11-14T20:38:30.400 (T0), Insight-HXMT/HE detected a short-duration GRB 251114B, which is also detected by Fermi/GBM (Fermi GBM team, GCN #42687). The Insight-HXMT/HE light curve mainly consists of a short pulse with a duration of about 2 s. The 1s peak rate, measured from T0-0.325 s, is 1373 cnts/sec. Insight-HXMT/HE detected a total of 3247 counts from this burst. The Insight-HXMT /HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251114B.png All measurements above are made with the CsI detectors of Insight-HXMT/HE operating in the regular mode with the energy range of about 60-900 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org View this GCN Circular online at https://gcn.nasa.gov/circulars/42739. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40803] GRB 251114B: GECAM-B detection of a short burst
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42738 SUBJECT: GRB 251114B: GECAM-B detection of a short burst DATE: 25/11/18 15:57:36 GMT FROM: zhangjinpeng(a)ihep.ac.cn Jin-Peng Zhang, Chen-Wei Wang, Chao Zheng, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered in-flight by a short burst, GRB 251114B, at 2025-11-14T20:38:30.100 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN#42687). According to the GECAM-B light curves in about 40-6000 keV, this burst mainly consists of multiple pulses with a duration (T90) of 3.4 +1.6/-2.0 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb251114B.png The time-averaged spectrum from T0-2 s to T0+2 s is best fitted by a power law function. The power law index is -1.97 +0.18/-0.16. The event fluence (10-1000 keV) in this time interval is (2.32 +0.22/-0.24)E-06 erg/cm^2. Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS). View this GCN Circular online at https://gcn.nasa.gov/circulars/42738. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40802] GRB 251117A: Fermi GBM observation
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42737 SUBJECT: GRB 251117A: Fermi GBM observation DATE: 25/11/18 15:50:37 GMT FROM: Elisabetta Bissaldi at Politecnico and INFN Bari <elisabetta.bissaldi(a)ba.infn.it> E. Bissaldi (Politecnico and INFN Bari) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 12:19:52.14 UT on 17 November 2025, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 251117A (trigger 785074797 / 251117514), which was also detected by the Fermi LAT (Holzmann Airasca et al., GCN 42729), SVOM/GRM (Wang et al., GCN 42731) and Swift/BAT-GUANO (DeLaunay et al. 2025, GCN 42732). The GBM on-ground location (GCN 42719) is consistent with the Fermi LAT position. The angle from the Fermi LAT boresight at the GBM trigger time is 50 degrees. The GBM light curve consists of a multi-peaked emission episode with a duration (T90) of about 1.3 s (50-300 keV). The time-averaged spectrum from T0-0.32 s to T0+1.15 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.80 +/- 0.08 and the cutoff energy, parameterized as Epeak, is 1.2 +/- 0.3 MeV. The event fluence (10-1000 keV) in this time interval is (2.04 +/- 0.08)E-06 erg/cm^2. The 64-ms peak photon flux measured starting from T0+0.32 s in the 10-1000 keV band is 11.1 +/- 1.1 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" View this GCN Circular online at https://gcn.nasa.gov/circulars/42737. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40801] GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42736 SUBJECT: GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection DATE: 25/11/18 15:46:36 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. Volnova (IKI), A. Pozanenko (IKI), A. S. Moskvitin (SAO RAS), V. Rumyantsev (CrAO), A. Novichonok (Petrozavodsk State University, KIAM), E. Klunko (ISTP), O. I. Spiridonova (SAO RAS), T. A. Fatkhullin (SAO RAS) report on behalf of IKI-GRB-FuN: We observed the optical afterglow (Palmerio et al., GCN 42223; Perez-Garcia et al., GCN 42225; Konno et al., GCN 42226; Martin-Carrillo et al., GCN 42227; Masi, GCN 42228; Palmerio et al., GCN 42229; Moskvitin et al., GCN 42230; Gompertz et al., GCN 42231; Lipunov et al., GCN 42235; Garnavich, GCN 42240; Watson et al., GCN 42241; López-Cámara et al., GCN 42242; Brosio et al., GCN 42251; Reguitti, GCN 42253; Quintana-Ansaldo et al., GCN 42254; Maksut et al., GCN 42256; Ghosh et al., GCN 42261; Quadri et al., GCN 42262; Adami et al., GCNs 42266, 42276, 42338; Peretto et al., GCN 42267; Ruocco et al., GCN 42269; Calapai, GCN 42275; Globus et al., GCN 42279; Evans, GCN 42281; Abidkhanov et al., GCN 42283; Siegel, GCN 42298; Leonini et al, GCN 42301; Méndez et al., GCN 42318; He et al., GCN 42319; Pavoni et al., GCN 42333; Bochenek and Perley, GCN 42334; Volnova et al., GCN 42396; Moskvitin et al., GCN 42399; Khosroshahi et al., GCN 42492; Hong et al., GCN 42569) of the GRB 251013C (The Fermi GBM team, GCN 42221; Rakotondrainibe et al., GCN 42222) with four facilities of the IKI GRB-FuN network: the 1-meter Zeiss-1000 telescope of the Koshka Observatory (INASAN) on Oct. 15 and 20, 2025, the 1.5-meter AZT-33IK telescope of Sayan Solar Observatory (Mondy) on Oct. 18-19, 21-23, 26-28, 2025, the 1-m SAO RAS telescope Zeiss-1000 equipped with the CCD-photometer on Oct. 17-18, 20, 24-25, 28, 2025, and the ZTSh 2.6m telescope at the CrAO observatory on Oct. 25, 2025. The preliminary photometry and observational details are the following: Date UT start t-T0 Exp. Filter OT Err. UL FWHM," Observatory/Scope (mid,days) (n*s) (3sigma) 2025-10-15 17:37:25 2.07846 116*90 R n/d n/d 21.5 3.5 Koshka/Ziess-1000 2025-10-17 16:59:44 3.99336 10*300 Rc 20.41 0.03 23.0 3.9 SAO/Zeiss-1000 2025-10-18 14:42:05 4.89113 2*120 R 20.82 0.15 21.5 2.0 Mondy/AZT-33IK 2025-10-18 18:54:43 5.08147 10*300 Rc 21.02 0.04 23.4 2.9 SAO/Zeiss-1000 2025-10-19 12:36:06 5.81400 35*120 R 21.58 0.06 23.2 1.7 Mondy/AZT-33IK 2025-10-20 18:43:33 7.08815 40*180 R 20.70 0.14 21.8 2.6 Koshka/Ziess-1000 2025-10-20 19:59:38 7.12682 13*300 Rc 21.61 0.11 22.7 5.4 SAO/Zeiss-1000 2025-10-21 12:30:55 7.81336 40*120 R 21.89 0.09 23.0 2.0 Mondy/AZT-33IK 2025-10-22 12:29:59 8.85439 37*120 R 21.63 0.12 22.4 2.1 Mondy/AZT-33IK 2025-10-23 12:05:16 9.79207 35*120 R 22.31 0.22 22.5 2.7 Mondy/AZT-33IK 2025-10-23 19:20:37 10.08190 6*300 Rc 22.31 0.25 22.5 2.3 SAO/Zeiss-1000 2025-10-24 18:54:05 11.06288 6*300 Rc n/d n/d 22.0 2.4 SAO/Zeiss-1000 2025-10-25 16:11:31 11.97093 38*120 R 21.70 0.08 23.1 2.5 CrAO/ZTSh 2025-10-26 13:33:51 12.86054 45*120 R 21.70 0.10 22.9 2.2 Mondy/AZT-33IK 2025-10-27 12:22:47 13.81189 45*120 R 22.13 0.15 22.7 2.6 Mondy/AZT-33IK 2025-10-28 12:32:36 14.81800 44*120 R 22.23 0.25 22.4 3.6 Mondy/AZT-33IK 2025-10-28 19:37:11 15.11907 10*300 Rc 22.46 0.22 22.8 3.6 SAO/Zeiss-1000 The photometry is based on several nearby SDSS stars (R-magnitudes Lupton's transformation) and is not corrected for the Galactic extinction; all magnitudes are in Vega system. The light curve based on our previous and presented above data can be found at https://heaiki.ru/lvc/r/PD/GRB251013C/GRB251013C_LC.jpg There are at least three bumps that can be seen in the LC, the first re-brightening already mentioned earlier (Méndez et al., GCN 42318; Adami et al., GCN 42338). The second bump is on the 9th day, and the 3rd bump has the maximum between 12 and 13 days. The last bump could be related to a supernova associated with GRB 251013C. Given the redshift of the gamma-ray burst source z = 0.572 (Martin-Carrillo et al., GCN 42227) maximum in the LC on days 12–13 may be a supernova associated with GRB 251013C. If so, the absolute magnitude of the SN at its maximum is M_R > -20.3, which is consistent with the distribution of absolute maxima of SNe associated with GRBs (see, e.g., Belkin et al., 2024). View this GCN Circular online at https://gcn.nasa.gov/circulars/42736. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40800] LIGO/Virgo/KAGRA S251117dq: Updated Sky localization
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42735 SUBJECT: LIGO/Virgo/KAGRA S251117dq: Updated Sky localization DATE: 25/11/18 13:41:03 GMT FROM: Nelson Christensen at Obs.de la Cote dAzur,Nice <nelson.christensen(a)oca.eu> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) data around the time of the compact binary merger (CBC) candidate S251117dq (GCN Circular 42727). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S251117dq For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 1547 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2699 +/- 860 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/42735. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40799] GRB 251116D: Insight-HXMT/HE detection
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42734 SUBJECT: GRB 251116D: Insight-HXMT/HE detection DATE: 25/11/18 11:24:24 GMT FROM: Xinghao Luo at SVOM/GRN <2952704891(a)qq.com> Xing-hao Luo, Chen-Wei Wang, Chao Zheng, and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team: At 2025-11-16T19:22:36.500 (T0), Insight-HXMT/HE detected the long burst GRB 251116D, which is also detected by AstroSat/CZTI (Harsha K. H. et.al., GCN #42175) , Konus-Wind and Glowbug (C.C. Cheung et.al., GCN #42178) The Insight-HXMT/HE light curve mainly consists of multiple pulses with a T90 of 38 +5/-12 s. The 1s peak rate, measured from T0+0.5 s, is 4335 cnts/sec. Insight-HXMT/HE detected a total of 26858 counts form this burst. The HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251116D.png All measurements above are made with the CsI detectors of Insight-HXMT/HE operating in the regular mode with the energy range of about 60-900 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org View this GCN Circular online at https://gcn.nasa.gov/circulars/42734. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40798] GRB 251115A: Swift-XRT observations
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42733 SUBJECT: GRB 251115A: Swift-XRT observations DATE: 25/11/18 10:09:35 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> S. Dichiara (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), D.N. Burrows (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Fermi/LAT-detected burst GRB 251115A in a series of observations tiled on the sky. The total exposure time is 4.9 ks, distributed over 5 tiles; the maximum exposure at a single sky location in the tiling was 2.1 ks. The data were collected between T0+35.6 ks and T0+80.1 ks, and are entirely in Photon Counting (PC) mode. Six uncatalogued X-ray sources have been detected, however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Details of these sources are given below: Source 1: RA (J2000.0): 330.1753 = 22h 00m 42.06s Dec (J2000.0): -9.3644 = -09d 21' 51.7" Error: 8.5 arcsec (radius, 90% conf.) Count-rate: (3.7 [+2.2, -1.6])e-3 ct s^-1 Distance: 660 arcsec from Fermi/LAT position. Source 2: RA (J2000.0): 330.0683 = 22h 00m 16.38s Dec (J2000.0): -9.4681 = -09d 28' 05.0" Error: 8.6 arcsec (radius, 90% conf.) Count-rate: (6.2 [+3.9, -2.8])e-3 ct s^-1 Distance: 1100 arcsec from Fermi/LAT position. Source 3: RA (J2000.0): 330.0530 = 22h 00m 12.72s Dec (J2000.0): -9.1976 = -09d 11' 51.3" Error: 5.8 arcsec (radius, 90% conf.) Count-rate: (4.3 [+2.3, -1.7])e-3 ct s^-1 Distance: 437 arcsec from Fermi/LAT position. Flux: (2.26 [+1.23, -0.91])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 4: RA (J2000.0): 330.2127 = 22h 00m 51.06s Dec (J2000.0): -9.1608 = -09d 09' 38.9" Error: 14.1 arcsec (radius, 90% conf.) Count-rate: (9.6 [+4.4, -3.4])e-3 ct s^-1 Distance: 152 arcsec from Fermi/LAT position. Flux: (3.6 [+1.6, -1.2])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 6: RA (J2000.0): 329.7737 = 21h 59m 05.69s Dec (J2000.0): -8.8965 = -08d 53' 47.2" Error: 5.6 arcsec (radius, 90% conf.) Count-rate: 0.0113 [+0.0055, -0.0042] ct s^-1 Distance: 1756 arcsec from Fermi/LAT position. Flux: (4.5 [+2.2, -1.7])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 7: RA (J2000.0): 329.8892 = 21h 59m 33.40s Dec (J2000.0): -8.9944 = -08d 59' 39.8" Error: 6.6 arcsec (radius, 90% conf.) Count-rate: 0.0101 [+0.0049, -0.0038] ct s^-1 Distance: 1218 arcsec from Fermi/LAT position. Flux: (2.63 [+1.28, -0.99])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) A catalogued source was also detected. The results of the XRT-team automatic analysis of the tiled XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00140. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42733. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40797] GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42732 SUBJECT: GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst DATE: 25/11/18 05:14:33 GMT FROM: Jimmy DeLaunay at Penn State <delauj2(a)gmail.com> James DeLaunay (PSU), Samuele Ronchini (GSSI), Aaron Tohuvavohu (Cosmic Frontier), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC), Maia Williams (Northwestern) report: Swift/BAT did not localize GRB 251117A onboard (T0: 2025-11-17T12:19:52.14 UTC, Fermi Trig 785074797, SVOM/GRM GCN 42731) The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 10.0 in a 1.024 s analysis time bin, starting at T0 - 0.256 s. Using the NITRATES analysis, parameter estimation was performed to obtain the localization of this burst in the form of a HEALPIX Multi-Order Coverage (MOC) skymap. This localization accounts for both statistical and systematic errors. More details in the creation and calibration of these maps will soon be published (DeLaunay et al. 2025. in prep) The 90% credible area is 12,010 deg2 and the 50% credible area is 4,336 deg2. The integrated probability inside the coded field of view is 1%. The NITRATES skymap is consistent with the Ferm/GBM localization reported in the final position notice (GCN 42719). The combined Fermi/GBM+NITRATES 90% credible area is 439 deg2 and the 50% credible area is 120 deg2. The NITRATES and combined localizations are consistent with the Fermi/LAT localization (GCN 42729) A plot of the probability skymap can be viewed here: [skymap_plot](https://guano.swift.psu.edu/trigger_report?id=785074828/#:~:te… The probability skymap and joint skymap files can be downloaded from the links here #The probability skymap file can be downloaded from the link here [skymap_fits_file](https://guano.swift.psu.edu/files/785074828/0_n_PROBMAP) [joint_skymap_fits_file](https://guano.swift.psu.edu/files/785074828/0_n_JOI… Instructions on how to read and manipulate this map can be found here: https://guano.swift.psu.edu/documentation More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=785074828 GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/42732. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40796] GRB 251117A: SVOM/GRM observation of a short burst
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42731 SUBJECT: GRB 251117A: SVOM/GRM observation of a short burst DATE: 25/11/18 03:43:19 GMT FROM: Yue Wang <m18509381757(a)163.com> SVOM/GRM team: Yue Wang, Chen-Wei Wang, Wen-Jun Tan, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Olivier GODET (IRAP), Frédéric Piron (LUPM) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by GRB 251117A (SVOM trigger reference: sb25111701) at 2025-11-17T12:19:52.200 (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN #42719) and Fermi/LAT (Airasca et. al., GCN #42729) . With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multi-peaks with a T90 of 1.2 +1.4/-0.2 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb251117A.png In addition, the position of this burst, as determined by Fermi/LAT (RA=331.30, Dec = 5.57, GCN #42729), is located at about 39.52 degrees from the SVOM optical axis, which is inside the ECLAIRs field of view. But ECLAIRs was not taking data. With this localization, the time-averaged spectrum from T0-2 to T0+2 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.05 +0.10/-0.12 and the cutoff energy, parameterized as Epeak, is 1320 +780/-440 keV. The event fluence (10-1000 keV) in this time interval is (2.10 +0.17/-0.16)E-06 erg/cm^2. The localization of GRB 251117A in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb251117A_amati.png The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM/GRM point of contact for this burst is: Yue Wang (IHEP) (yuewang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/42731. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40795] GRB 251117A: Tiled Swift observations
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42730 SUBJECT: GRB 251117A: Tiled Swift observations DATE: 25/11/18 01:52:11 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a series of observations, tiled on the sky, of the Fermi/GBM GRB 251117A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/xrt_products/TILED_GRB00141 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. The probability of finding serendipitous sources, unrelated to the Fermi/GBM event is high: any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42730. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40794] GRB 251117A: Fermi-LAT detection
by GCN Circulars 18 Nov '25

18 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42729 SUBJECT: GRB 251117A: Fermi-LAT detection DATE: 25/11/18 00:50:18 GMT FROM: Rahul Gupta at NASA GSFC <rahul.gupta(a)nasa.gov> A. Holzmann Airasca (UniTrento and INFN Bari), S. Lopez (CNRS / IN2P3), N. Di Lalla (Stanford University) and R. Gupta (NASA GSFC) report on behalf of the Fermi-LAT Collaboration: On November 17, 2025, Fermi-LAT detected high-energy emission from GRB 251117A, which was also detected by Fermi-GBM (trigger 785074797 / 251117514, GCN 42719). The best LAT on-ground location is found to be: RA, Dec = 331.30, 5.57 (J2000) with an error radius of 0.72 deg (90 % containment, statistical error only). This was 51 deg from the LAT boresight at the time of the GBM trigger (T0 = 12:19:52.14 UT). The data from the Fermi-LAT shows a significant increase in the event rate that is spatially and temporally correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval 0 - 5 s after the GBM trigger is (3.4 ± 1.4) E-4 ph/cm2/s. The estimated photon index above 100 MeV is -2.8 ± 0.6. The highest-energy photon is a 0.9 GeV event which is observed ~ 2 seconds after the GBM trigger. A Swift ToO has been requested for this burst. The Fermi-LAT point of contact for this burst is Aldana Holzmann Airasca (a.holzmannairasca(a)unitn.it) The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. View this GCN Circular online at https://gcn.nasa.gov/circulars/42729. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40793] LAT GRB251117.51: Global MASTER-Net observations report
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42728 SUBJECT: LAT GRB251117.51: Global MASTER-Net observations report DATE: 25/11/17 23:11:42 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Tavrida robotic telescope [1] located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the LAT GRB251117.51 (trigger No 785074797,22h 05m 12.00s , +05d 34m 12.0s, R=0.719833) errorbox 11108 sec after trigger time at 2025-11-17 15:25:00 UT, with upper limit up to 16.0 mag. Observations started at twilight. The observations began at zenith distance = 39 deg. The sun altitude is -12.7 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the LAT GRB251117.51 errorbox 12105 sec after trigger time at 2025-11-17 15:41:37 UT, with upper limit up to 17.0 mag. The observations began at zenith distance = 38 deg. The sun altitude is -21.1 deg. The galactic latitude b = -39 deg., longitude l = 67 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3044995 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 11138 | 2025-11-17 15:25:00 | MASTER-Tavrida | (22h 06m 43.82s , +05d 59m 20.3s) | C | 60 | 15.1 | 11222 | 2025-11-17 15:26:23 | MASTER-Tavrida | (22h 10m 15.32s , +07d 18m 57.3s) | C | 60 | 16.0 | 11379 | 2025-11-17 15:29:01 | MASTER-Tavrida | (22h 03m 42.52s , +04d 40m 48.3s) | C | 60 | 16.0 | 12135 | 2025-11-17 15:41:37 | MASTER-Kislovodsk | (22h 06m 52.64s , +05d 11m 31.5s) | C | 60 | 16.6 | 12215 | 2025-11-17 15:42:57 | MASTER-Kislovodsk | (22h 03m 51.57s , +03d 16m 19.2s) | C | 60 | 16.4 | 12299 | 2025-11-17 15:44:20 | MASTER-Tavrida | (22h 01m 29.12s , +03d 23m 18.8s) | C | 60 | 16.0 | 13003 | 2025-11-17 15:56:04 | MASTER-Tavrida | (21h 59m 50.40s , +07d 17m 56.1s) | C | 60 | 15.8 | 13672 | 2025-11-17 16:07:13 | MASTER-Tavrida | (21h 55m 17.37s , +05d 59m 54.8s) | C | 60 | 16.0 | 13882 | 2025-11-17 16:10:44 | MASTER-Kislovodsk | (21h 56m 10.36s , +07d 02m 54.9s) | C | 60 | 17.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42728. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40792] LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42727 SUBJECT: LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate DATE: 25/11/17 22:03:09 GMT FROM: Alicia Calafat <alicia.calafat(a)ligo.org> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S251117dq during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2025-11-17 21:38:33.119 UTC (GPS time: 1447450731.119). The candidate was found by the Aframe [1], cWB [2], cWB BBH [3], GstLAL [4], MBTA [5], PyCBC Live [6], and SPIIR [7] analysis pipelines. S251117dq is an event of interest because its false alarm rate, as estimated by the online analysis, is 5.9e-15 Hz, or about one in 1e7 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S251117dq The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%). Assuming the candidate is astrophysical in origin, the probability that at least one of the compact objects is consistent with a neutron star mass (HasNS) is <1%. [8] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [8] Both HasNS and HasRemnant consider the support of several neutron star equations of state for maximum neutron star mass. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is <1%. The source chirp mass falls with highest probability in the bin (22.0, 44.0) solar masses, assuming the candidate is astrophysical in origin. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * amplfi.multiorder.fits,0, an initial localization generated by AMPLFI [9], distributed via GCN and SCiMMA notices about 19 seconds after the candidate event time. * bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [10], distributed via GCN and SCiMMA notices about 4 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,0. For the bayestar.multiorder.fits,0 sky map, the 90% credible region is 1701 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2201 +/- 621 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Marx et al. PRD 111, 042010 (2025) doi:10.1103/PhysRevD.111.042010 [2] Klimenko et al. PRD 93, 042004 (2016) doi:10.1103/PhysRevD.93.042004 [3] T. Mishra et al. PRD 105, 083018 (2022) doi:10.1103/PhysRevD.105.083018 [4] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. PRD 109, 042008 (2024) doi:10.1103/PhysRevD.109.042008 [5] Alléné et al. CQG 42, 105009 (2025) doi:10.1088/1361-6382/add234 [6] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a [7] Chu et al. PRD 105, 024023 (2022) doi:10.1103/PhysRevD.105.024023 [8] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [9] Chatterjee et al. MLST 5, 045030 (2024) doi:10.1088/2632-2153/ad8982 [10] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/42727. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40791] LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42727 SUBJECT: LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate DATE: 25/11/17 22:03:09 GMT FROM: Alicia Calafat <alicia.calafat(a)ligo.org> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S251117dq during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2025-11-17 21:38:33.119 UTC (GPS time: 1447450731.119). The candidate was found by the Aframe [1], cWB [2], cWB BBH [3], GstLAL [4], MBTA [5], PyCBC Live [6], and SPIIR [7] analysis pipelines. S251117dq is an event of interest because its false alarm rate, as estimated by the online analysis, is 5.9e-15 Hz, or about one in 1e7 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S251117dq The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%). Assuming the candidate is astrophysical in origin, the probability that at least one of the compact objects is consistent with a neutron star mass (HasNS) is <1%. [8] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [8] Both HasNS and HasRemnant consider the support of several neutron star equations of state for maximum neutron star mass. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is <1%. The source chirp mass falls with highest probability in the bin (22.0, 44.0) solar masses, assuming the candidate is astrophysical in origin. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * amplfi.multiorder.fits,0, an initial localization generated by AMPLFI [9], distributed via GCN and SCiMMA notices about 19 seconds after the candidate event time. * bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [10], distributed via GCN and SCiMMA notices about 4 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,0. For the bayestar.multiorder.fits,0 sky map, the 90% credible region is 1701 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2201 +/- 621 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Marx et al. PRD 111, 042010 (2025) doi:10.1103/PhysRevD.111.042010 [2] Klimenko et al. PRD 93, 042004 (2016) doi:10.1103/PhysRevD.93.042004 [3] T. Mishra et al. PRD 105, 083018 (2022) doi:10.1103/PhysRevD.105.083018 [4] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. PRD 109, 042008 (2024) doi:10.1103/PhysRevD.109.042008 [5] Alléné et al. CQG 42, 105009 (2025) doi:10.1088/1361-6382/add234 [6] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a [7] Chu et al. PRD 105, 024023 (2022) doi:10.1103/PhysRevD.105.024023 [8] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [9] Chatterjee et al. MLST 5, 045030 (2024) doi:10.1088/2632-2153/ad8982 [10] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/42727. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40790] GRB 251116C: Swift/BAT arcminute localization of a burst
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42726 SUBJECT: GRB 251116C: Swift/BAT arcminute localization of a burst DATE: 25/11/17 19:29:14 GMT FROM: Jimmy DeLaunay at Penn State <delauj2(a)gmail.com> James DeLaunay (PSU), Samuele Ronchini (GSSI), Aaron Tohuvavohu (Cosmic Frontier), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: Swift/BAT did not localize GRB 251116C onboard (T0: 2025-11-16T15:57:41 UTC, SVOM/ECLAIRS GCN 42703). In a ground search of BAT survey data, the GRB was detected at a S/N of 7.2 in a single 300 s image (14 - 80 keV) starting at ~T0 - 192 s. The BAT position is RA, Dec = 335.3327, -10.3401 deg which is RA(J2000) = 22h 21m 19.9s Dec(J2000) = -10d 20′ 24.4″ with an estimated uncertainty of 3 arcmin radius. Source X1 detected by Swift/XRT (GCN 42721) falls inside this error circle. View this GCN Circular online at https://gcn.nasa.gov/circulars/42726. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40789] LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42725 SUBJECT: LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations DATE: 25/11/17 18:02:48 GMT FROM: Kenta Taguchi <kentagch(a)kusastro.kyoto-u.ac.jp> Kenta Taguchi, Miho Kawabata (Kyoto U.); Ryosuke Itoh (Ibara City); Hiroshi Akitaya, Tomoki Morokuma (ARC/Chiba Tech); Jun Takahashi, Satoshi Honda, Miyako Tozuka, Shigeru Takahashi (Univ. of Hyogo/NHAO); Koji Kawabata, Tatsuya Nakaoka (Hiroshima U.); Haruna Hagio, Ryotaro Kato, Atsuya Ochi, Mahito Sasada, Ichiro Takahashi (Science Tokyo); Nozomu Tominaga, Yousuke Utsumi, Michitoshi Yoshida, Haibin Zhang, Masafumi Niwano, Mitsuru Kokubo, Yuhei Iwata (NAOJ); Masaomi Tanaka (Tohoku University); Yuu Niino, Taiga Sasaoka (U. of Tokyo); Yumiko Oasa, Takahiro Kanai (Saitama Univ.); Yuichiro Sekiguchi (Toho University) on behalf of the J-GEM collaboration We report imaging follow-up observations for the gravitational-wave event S251112cm (GCN 42650). Our observations started at 2025-11-12 19:09:29 UT (MJD=60991.80), approximately 3.8 hours after the event, and ended at 2025-11-17 10:18:47 UT (MJD=60996.43). We conducted galaxy-targeted observations of 135 galaxies (see the table below), selected from the GLADE catalog (v2.4; Dalya et al. 2018) within the probability skymap of S251112cm, using the telescopes and instruments listed below. After screening out known minor planets, we did not find any apparent transient candidates in these galaxies down to the 5-sigma limiting magnitudes in the AB magnitude system summarized below. galid ra dec dist g r R i I z J H Ks NoFilt obsid --------------- -------- -------- ------ ---- ---- ---- ---- ---- ---- ---- ---- ---- ------ ------- GL000835-335128 2.1441 -33.8578 97.4 -- -- 17.2 -- -- -- -- -- -- -- 1 GL094621+030417 146.5879 3.0713 86.9 19.6 18.6 -- 18.8 -- -- -- -- -- 18.3 2,3 GL095807+102135 149.5288 10.3598 77.8 20.4 19.9 19.8 19.8 18.0 -- -- 15.8 -- -- 4,5,2 GL102235+195314 155.6440 19.8871 82.7 19.9 19.6 18.7 19.6 18.0 -- -- -- -- 19.0 5,2,3 GL094620+030244 146.5848 3.0455 87.3 19.6 18.6 -- 18.8 -- -- -- -- -- 18.3 2,3 GL094604+042412 146.5148 4.4033 71.9 18.0 17.1 -- 17.2 -- -- -- -- -- 18.5 2,3 GL093427-023015 143.6119 -2.5041 78.1 19.6 18.6 20.1 18.9 -- -- -- 16.8 -- 14.9 2,3,4 GL100140+104523 150.4186 10.7564 78.3 19.9 19.5 18.6 19.5 17.9 -- -- -- -- 18.6 5,2,3 GL103939+251921 159.9126 25.3226 75.2 19.8 -- 19.9 19.1 -- -- -- 15.8 -- 18.9 2,3,4 GL092022-075250 140.0914 -7.8807 49.6 19.2 18.4 19.6 18.6 -- -- -- 17.2 -- 18.5 2,4,3 GL224424-000943 341.1015 -0.1620 70.1 -- -- 18.2 -- -- -- -- 18.8 -- 19.4 1,3,6 GL094909+022851 147.2866 2.4808 88.5 20.4 19.6 15.3 19.3 15.1 -- -- -- -- 14.5 5,2,3 GL094559+030843 146.4950 3.1453 85.8 19.7 19.0 -- 18.8 -- -- -- -- -- 18.2 2,3 GL102905+221246 157.2692 22.2128 92.9 20.0 19.4 -- 19.2 -- -- -- -- -- 19.1 2,3 GL230311-085921 345.7959 -8.9890 104.2 20.4 19.6 -- 19.8 -- -- -- -- 17.6 19.2 2,3,6 GL094036+033437 145.1516 3.5769 73.2 18.3 17.3 -- 17.5 -- 16.5 -- -- -- -- 7,2 GL234745-280828 356.9380 -28.1410 124.7 18.3 17.6 -- 23.8 -- -- -- -- -- -- 2 GL234045-244137 355.1890 -24.6937 98.5 -- 18.5 -- 19.2 -- -- -- -- -- 18.9 3,2 GL230344-071330 345.9325 -7.2250 74.5 20.2 19.7 18.6 19.9 18.2 18.2 -- -- -- 19.0 2,7,3,5 GL103958+240528 159.9915 24.0912 91.6 19.7 18.8 -- 18.8 -- -- -- -- -- -- 2 GL093941-001406 144.9204 -0.2351 72.2 17.1 16.5 -- 16.4 -- -- -- -- -- 17.8 2,3 GL103130+245210 157.8750 24.8693 90.7 19.6 18.6 -- 18.4 -- -- -- -- -- 18.7 2,3 GL110800+365220 166.9981 36.8722 116.9 20.2 19.4 -- 19.4 -- -- -- -- -- 19.0 2,3 GL234729-280634 356.8690 -28.1093 120.3 18.3 17.6 -- 23.8 -- -- -- -- -- -- 2 GL235137-282154 357.9030 -28.3651 121.0 18.4 18.0 -- -- -- -- -- -- -- 18.6 3,2 GL101229+122237 153.1220 12.3771 79.2 19.7 19.3 -- 19.2 -- -- -- -- -- 18.7 2,3 GL093411+001431 143.5443 0.2420 70.9 20.2 19.7 18.6 19.7 17.9 -- -- 17.8 -- 17.7 5,2,3,4 GL225651-085803 344.2120 -8.9674 72.7 -- -- -- -- -- -- 17.9 17.9 -- 19.0 3,6 GL225542-052943 343.9238 -5.4953 43.8 19.2 -- -- 18.2 -- -- -- -- -- 19.4 2,3 GL104801+281447 162.0045 28.2464 92.0 21.6 21.2 -- 21.2 -- -- -- -- -- 21.1 2,3 GL092514-064300 141.3074 -6.7166 88.7 20.0 19.4 -- 19.4 -- -- -- -- -- 18.9 2,3 GL104437+261054 161.1539 26.1816 90.8 -- -- -- -- -- -- -- -- -- 18.9 3 GL232431-190333 351.1310 -19.0591 110.5 19.9 18.8 -- 18.9 -- -- -- 18.1 18.1 19.0 2,3,6 GL000254-341408 0.7269 -34.2357 98.9 -- -- 16.7 -- 17.2 -- -- -- -- -- 5 GL091049-085331 137.7050 -8.8919 27.7 20.0 19.3 -- 19.4 -- -- -- -- -- 18.7 2,3 GL223407+053413 338.5282 5.5703 65.5 19.9 18.9 -- 19.6 -- -- 17.4 17.9 17.5 -- 2,6 GL235624-312111 359.0995 -31.3532 125.1 -- -- -- -- -- -- -- -- -- 17.9 3 GL104703+263235 161.7609 26.5430 91.8 19.7 -- -- 19.0 -- -- -- -- -- 18.7 2,3 GL225138-053326 342.9087 -5.5573 53.2 19.9 19.4 -- 19.8 -- -- -- -- -- 19.2 2,3 GL225641-072245 344.1724 -7.3790 64.2 19.2 18.1 -- 18.5 -- -- -- -- -- -- 2 GL095230+020916 148.1235 2.1544 72.2 19.6 19.0 -- 18.7 -- -- -- -- -- 18.6 2,3 GL095730+080729 149.3742 8.1246 94.6 -- -- -- -- -- -- -- -- -- 19.0 3 GL103617+265744 159.0691 26.9623 92.1 19.5 19.1 -- 19.0 -- -- -- -- -- 19.1 2,3 GL234743-280838 356.9300 -28.1439 117.6 18.3 17.6 -- 23.8 -- -- -- -- -- -- 2 GL093635+010700 144.1473 1.1165 71.3 19.5 18.6 20.6 18.8 -- -- -- 16.2 -- -- 2,4 GL092056-094336 140.2319 -9.7268 56.4 -- -- -- -- -- -- -- -- -- 18.7 3 GL094617+054231 146.5710 5.7087 44.7 19.4 18.8 19.9 18.7 -- 17.1 -- 15.3 -- -- 7,2,4 GL094541+045631 146.4228 4.9419 54.0 19.9 19.2 -- 19.3 -- 17.9 -- -- -- -- 7,2 GL104245+265038 160.6860 26.8438 87.9 20.1 19.6 -- 19.4 -- -- -- -- -- 18.8 2,3 GL110427+381232 166.1138 38.2089 135.9 -- 18.2 -- 17.9 -- 18.1 -- -- -- 18.5 7,3 GL094901+041811 147.2530 4.3030 88.8 -- -- -- -- -- -- -- -- -- 18.6 3 GL094410+022437 146.0433 2.4103 86.7 20.1 19.3 -- -- -- -- -- -- -- -- 2 GL232149-164309 350.4551 -16.7192 85.6 18.6 17.6 -- 18.0 -- -- -- -- -- 19.0 2,3 GL230658-091710 346.7422 -9.2861 103.7 19.8 18.9 -- 19.1 -- -- -- 17.7 -- 18.8 2,3,6 GL101301+170203 153.2554 17.0342 95.9 19.3 19.0 20.6 18.9 17.2 -- -- 16.0 -- 18.6 5,2,4,3 GL093434+000522 143.6430 0.0894 68.4 19.9 19.5 18.6 19.7 17.9 -- -- -- -- 17.6 5,2,3 GL104827+263502 162.1140 26.5838 88.5 27.3 27.3 -- 27.3 -- -- -- -- -- 27.0 2,3 GL110558+362425 166.4920 36.4070 108.1 20.2 19.8 -- 19.5 -- -- -- -- -- 18.6 2,3 GL225544-062712 343.9352 -6.4533 104.7 19.9 19.2 -- 19.5 -- -- -- -- -- -- 2 GL100135+124554 150.3962 12.7649 91.2 19.8 19.3 -- 19.2 -- -- -- -- -- 18.8 2,3 GL235754-314854 359.4764 -31.8151 126.6 -- -- -- -- -- -- -- -- -- 18.0 3 GL100430+144608 151.1230 14.7690 101.5 19.3 18.6 20.0 18.4 -- -- -- 18.0 -- 14.3 4,2,3 GL100545+101636 151.4356 10.2767 104.9 -- -- -- -- -- -- -- -- -- 18.7 3 GL095757+102556 149.4862 10.4323 76.5 20.3 19.8 19.8 19.7 18.0 -- -- 15.8 -- -- 4,5,2 GL095905+102140 149.7714 10.3611 77.6 18.0 16.7 18.6 -- 18.0 -- -- -- -- -- 5,2 GL110759+352748 166.9957 35.4633 125.8 19.7 19.0 -- 19.0 -- -- -- -- -- 18.4 2,3 GL104739+261746 161.9130 26.2961 91.8 19.1 18.0 -- 18.3 -- -- -- -- -- 18.4 2,3 GL095351+085241 148.4630 8.8781 92.4 19.6 18.7 18.4 18.5 17.6 -- -- -- -- 18.8 2,3,5 GL232338-190035 350.9101 -19.0097 112.2 19.7 18.5 -- 19.1 -- -- -- -- -- 19.2 2,3 GL233923-222956 354.8438 -22.4989 112.9 19.2 18.9 -- 19.2 -- -- -- -- -- -- 2 GL120532+513017 181.3840 51.5047 124.3 20.4 19.7 -- 19.4 -- -- -- -- -- 18.8 2,3 GL110916+360116 167.3172 36.0212 92.7 19.9 19.1 -- 19.3 -- -- -- -- -- 18.1 2,3 GL230009-083953 345.0359 -8.6647 107.0 20.2 19.6 -- 19.6 -- -- -- -- -- -- 2 GL110505+352157 166.2693 35.3657 108.9 20.1 19.4 -- 19.1 -- -- -- -- -- 18.1 2,3 GL104552+255705 161.4677 25.9515 90.5 19.6 18.9 -- 18.5 -- -- -- -- -- 18.2 2,3 GL110955+365648 167.4810 36.9465 132.5 20.6 20.0 -- 19.7 -- -- -- -- -- 19.1 2,3 GL094900+022748 147.2477 2.4633 82.6 -- -- -- -- -- -- -- -- -- 14.5 3 GL102626+173038 156.6065 17.5105 80.7 -- -- -- -- -- -- -- -- -- 18.8 3 GL104607+255417 161.5305 25.9049 92.1 19.6 18.9 -- 18.5 -- -- -- -- -- 18.2 2,3 GL234615-280557 356.5627 -28.0990 121.6 -- 18.5 -- 18.8 -- -- -- -- -- -- 2 GL103139+255902 157.9119 25.9840 91.5 18.9 18.6 -- 18.2 -- 18.0 -- -- -- 19.1 7,2,3 GL102241+205133 155.6709 20.8590 107.4 -- -- -- -- -- -- -- -- -- 19.2 3 GL113253+433054 173.2190 43.5150 106.2 23.4 23.1 -- 19.6 -- -- -- -- -- 21.3 2,3 GL095106+090031 147.7751 9.0085 75.2 20.4 19.8 20.0 19.6 18.1 -- -- 17.7 -- 18.9 5,4,2,3 GL093744+024542 144.4330 2.7616 97.9 20.4 19.5 20.7 19.7 -- -- -- -- -- -- 2,4 GL091711-044508 139.2939 -4.7521 51.0 19.6 19.1 19.6 18.8 -- -- -- 17.4 -- 18.0 2,3,4 GL104642+255554 161.6770 25.9317 89.6 20.0 19.4 -- 19.0 -- -- -- -- -- 18.6 2,3 GL102917+260557 157.3200 26.0991 73.6 17.7 -- -- -- -- -- -- -- -- -- 2 GL110958+370810 167.4932 37.1360 113.7 20.2 -- -- 19.4 -- -- -- -- -- -- 2 GL111208+352707 168.0335 35.4520 108.8 20.2 18.8 -- 19.5 -- -- -- -- -- 17.9 2,3 GL094955+090949 147.4781 9.1637 75.6 18.2 17.3 19.7 17.1 15.5 -- -- 17.8 -- -- 5,2,4 GL100836+181353 152.1515 18.2313 73.9 -- -- 20.0 -- -- -- -- 18.2 -- -- 4 GL093411+001430 143.5440 0.2417 66.7 20.2 19.7 17.4 19.7 17.0 -- -- 17.2 -- 13.9 5,2,3,4 GL130847+621618 197.1938 62.2716 118.2 19.8 19.1 -- 18.8 -- -- -- -- -- 18.0 2,3 GL121329+504429 183.3722 50.7415 134.9 19.7 19.2 -- 19.0 -- -- -- -- -- -- 2 GL110542+350704 166.4263 35.1178 125.8 -- -- -- -- -- -- -- -- -- 17.9 3 GL233707-202747 354.2789 -20.4631 115.3 19.0 17.8 -- 18.2 -- -- -- -- -- -- 2 GL225223+010533 343.0941 1.0926 71.3 20.2 18.9 -- 19.2 -- -- -- -- -- -- 2 GL123208+562816 188.0340 56.4711 66.5 20.4 19.9 -- 22.2 -- -- -- -- -- 19.8 2,3 GL123221+563923 188.0891 56.6564 66.6 -- -- -- -- -- -- -- -- -- 17.9 3 GL120251+483811 180.7111 48.6363 49.4 20.1 19.7 -- 19.8 -- -- -- -- -- 18.2 2,3 GL110841+360940 167.1716 36.1610 121.1 -- -- -- -- -- -- -- -- -- 12.3 3 GL092046-080322 140.1927 -8.0562 85.6 -- -- -- -- -- -- -- -- -- 18.5 3 GL231645-185257 349.1889 -18.8825 109.5 19.2 -- -- 18.4 -- -- -- -- -- -- 2 GL130737+621258 196.9038 62.2160 121.1 20.2 19.7 -- 19.6 -- -- -- -- -- 17.9 2,3 GL104827+263501 162.1137 26.5837 91.4 27.3 27.3 -- 27.3 -- -- -- -- -- -- 2 GL120945+563125 182.4386 56.5235 115.1 -- -- -- -- -- -- -- -- -- 17.8 3 GL231022-084119 347.5910 -8.6886 103.0 18.3 17.2 -- 17.4 -- -- -- -- -- -- 2 GL091906-064215 139.7744 -6.7042 87.6 -- -- -- -- -- -- -- -- -- 17.6 3 GL113906+431450 174.7746 43.2473 106.3 20.4 19.9 -- 19.7 -- -- -- -- -- -- 2 GL123600+541315 189.0006 54.2208 77.6 20.2 19.4 -- 19.6 -- -- -- -- -- -- 2 GL111118+352308 167.8252 35.3855 108.8 20.1 19.3 -- 19.9 -- -- -- -- -- 18.1 2,3 GL225716-105700 344.3147 -10.9499 105.2 19.7 18.4 -- 18.9 -- -- -- -- -- -- 2 GL094953+090545 147.4705 9.0959 81.5 15.9 -- 19.7 -- 15.5 -- -- -- -- -- 5,4 GL114916+460713 177.3185 46.1203 94.5 -- -- -- -- -- -- -- -- -- 18.3 3 GL230009-124828 345.0368 -12.8079 50.6 20.1 19.1 -- 19.3 -- -- -- -- -- -- 2 GL114803+461028 177.0139 46.1746 108.5 -- -- -- -- -- -- -- -- -- 18.3 3 GL111451+353008 168.7137 35.5022 93.5 19.9 19.1 -- 19.2 -- -- -- -- -- 17.9 2,3 GL093745+024450 144.4378 2.7473 101.6 20.4 19.5 -- 19.7 -- -- -- -- -- -- 2 GL104532+240900 161.3845 24.1501 88.9 20.2 19.5 -- 19.0 -- -- -- -- -- -- 2 GL120446+491112 181.1925 49.1865 104.5 -- -- -- -- -- -- -- -- -- 17.9 3 GL111522+353007 168.8413 35.5020 92.4 19.9 19.1 -- 19.2 -- -- -- -- -- 17.9 2,3 GL111507+363224 168.7802 36.5401 107.1 20.2 19.3 -- 19.2 -- -- -- -- -- 18.2 2,3 GL103546+210253 158.9420 21.0481 102.5 17.5 -- 18.8 -- 18.0 -- -- -- -- 18.8 5,3 GL111535+363033 168.8966 36.5092 108.8 20.2 19.3 -- 19.2 -- -- -- -- -- 17.9 2,3 GL232235-130539 350.6470 -13.0941 102.5 19.9 18.9 -- 19.0 -- -- -- -- -- -- 2 GL112646+391558 171.6918 39.2662 90.6 -- -- -- -- -- -- -- -- -- 17.8 3 GL111734+360351 169.3902 36.0641 112.8 19.9 19.3 17.8 19.2 16.9 -- -- -- -- 17.8 2,3,5 GL094937+090019 147.4041 9.0053 75.4 18.9 18.1 15.9 17.8 15.5 -- -- 18.1 -- -- 5,2,4 GL111703+360828 169.2646 36.1411 110.5 20.3 19.6 17.8 19.6 16.9 -- -- -- -- -- 2,5 GL112719+383952 171.8290 38.6645 93.8 20.3 -- -- 19.2 -- -- -- -- -- 17.7 2,3 GL122635+525934 186.6451 52.9929 94.6 -- -- -- -- -- -- -- -- -- 18.2 3 GL112001+360603 170.0025 36.1007 110.3 20.5 19.6 -- 19.5 -- -- -- -- -- -- 2 GL113009+383713 172.5390 38.6204 93.3 -- -- -- -- -- -- -- -- -- 17.8 3 GL232407-115139 351.0290 -11.8607 108.1 19.7 18.6 -- 19.1 -- -- -- -- -- -- 2 References for obsid: 1: BAO101cm: 101 cm telescope at Bisei Astronomical Observatory and CCD optical camera (B, V, Rc, Ic) 2: Seimei-TriCCS: 380 cm Seimei telescope (g, r, i) 3: Kiso Schmidt: 105 cm Schmidt telescope at Kiso Observatory and Tomo-e Gozen 20 deg2 fov camera (no filter) 4: Kanata-HONIR: 150 cm Kanata telescope at Higashi-Hiroshima Observatory and HONIR -- a 2 channel imager (Rc and H or J) (Akitaya et al. 2014, Proc. SPIE 9147, 91474O) 5: MITSuME-Akeno: 50 cm MITSuME telescope at Akeno Observatory and a 3 color imager (g, Rc, Ic); The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, 73, 1, 4-24; https://github.com/MNiwano/Eclaire) 6: Nayuta-NIC: 200 cm Nayuta telescope at Nishi-Harima Astronomical Observatory and Nishiharima Infrared Camera, NIC (J, H, Ks) 7: SaCRA-MuSaSHI: 55 cm SaCRA telescope at Saitama University and MuSaSHI (r, i, z) (Oasa et al., 2020, proc. SPIE, 11447, 114475Z) View this GCN Circular online at https://gcn.nasa.gov/circulars/42725. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40788] LIGO/Virgo/KAGRA S251112cm: Classification of reported candidates with SOAR/Goodman
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42724 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Classification of reported candidates with SOAR/Goodman DATE: 25/11/17 16:41:19 GMT FROM: André Santos at Centro Brasileiro de Pesquisas Físicas (CBPF) <andsouzasanttos(a)gmail.com> A. Santos (CBPF), C. D. Kilpatrick (Northwestern), C. R. Bom (CBPF), L. Santana-Silva (CBPF), P. Darc (CBPF), Gabriel Teixeira (CBPF), C. Mendes de Oliveira (IAG-USP) report on behalf of the STEP-GW collaboration Following the subsolar-mass gravitational-wave candidate S251112cm (GCN 42650, 42690), we conducted optical spectroscopic follow-up of four transients: 2025adiw, 2025adim, 2025adhf, and 2025adjf using the Goodman High-Throughput Spectrograph on the SOAR 4.1 m telescope at Cerro Pachón, Chile. Observations were performed on UT 2025 Nov 17 with the 400 l/mm M1 grating, 2×2 binning. For each source we obtained two 900 s exposures and coadded them for analysis. Each target was submitted for spectrum acquisition using the AEON queue. We classified 2025adim, 2025adiw, and 2025adhf as Type Ia supernovae based on SNID-SAGE spectral matches and identifiable SN Ia features. For 2025adjf, the spectra were heavily contaminated by host-galaxy light, preventing a definitive classification, and we instead report the host galaxy redshift based on nebular emission lines in the extracted spectrum. Our classification and redshift estimates are listed as follows: | AT Name | Classification | redshift | |----------|----------------|----------| | [2025adim](https://www.wis-tns.org/object/2025adim) | SN Ia | 0.091 | | [2025adiw](https://www.wis-tns.org/object/2025adiw) | SN Ia | 0.165 | | [2025adhf](https://www.wis-tns.org/object/2025adhf) | SN Ia | 0.098 | | [2025adjf](https://www.wis-tns.org/object/2025adjf) | - | 0.124 | All classified events are best matched to templates of normal or 91T-like SNe Ia at redshifts inconsistent with the expected distance for S251112cm, and thus are unlikely to be associated with the GW candidate. These results are based on observations obtained through the Astronomical Event Observatory Network (AEON), a joint endeavor of Las Cumbres Observatory and NSF NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the U.S. National Science Foundation. View this GCN Circular online at https://gcn.nasa.gov/circulars/42724. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40787] GRB 251116B: SVOM/VT optical upper limit
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42723 SUBJECT: GRB 251116B: SVOM/VT optical upper limit DATE: 25/11/17 16:17:41 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Y. N. Ma, Z. H. Yao, Y. Xu, X. H. Han, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. R. Xu, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA), M. Pillas (IAP), M.G. Bernardini (INAF-OAB, LUPM) report on behalf of the SVOM/VT team. SVOM/VT performed ToO observation on GRB 251116B (SVOM burst-id sb25111604, Pillas et al., GCN 42702). The observation started on 2025-11-17T01:05:38 UT (i.e. 9.55 hour post trigger) in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channel simultaneously. Inside the error box of SVOM/ECL (Pillas et al., GCN 42702) and the 6 sources reported by EP-FXT (Li et al., GCN 42709), we did not detect any new uncatalogued sources. Also no significant variation was found for the catalogued sources within EP-FXT's error circles. The 3 sigma upper limit magnitudes are derived as below: Mid time | Band | Exposure Time | 3 sigma upper limit 10.0 hour VT_B 19*70 sec >23.3 mag 10.0 hour VT_R 22*70 sec >23.3 mag Our result is consistent with the LCO's observation (Turpin et al., GCN 42706). The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS. View this GCN Circular online at https://gcn.nasa.gov/circulars/42723. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40786] LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42722 SUBJECT: LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results DATE: 25/11/17 15:38:01 GMT FROM: Zhengyan Liu at USTC <ustclzy(a)mail.ustc.edu.cn> Z. Y. Liu, W. Zhao, J.-A. Jiang, Z. L. Xu, D. Z. Meng, M. X. Cai, T. G. Wang, X. Kong, Z. G. Dai, L. L. Fan (USTC), Z. P. Jin, Y. Z. Fan (PMO) report on behalf of the WFST Collaboration: Following the detection of the sub-solar mass merger candidate S251112cm (the LIGO-Virgo-Kagra Collaboration, GCN 42650), we conducted follow-up observations focused on the northern region of the initial bayestar skymap (GCN 42650) using the newly deployed 2.5-meter Wide Field Survey Telescope (WFST Collaboration; Wang et al., 2023) at the Lenghu Astronomical Observation Base (Qinghai province, China). Observations began at UTC 2025-11-13T11:29:36, corresponding to ~20.2 hours after the merger event (UTC 2025-11-12T15:18:45). The follow-ups lasted for three nights until UTC 2025-11-15T23:16:16. We observed in WFST g, r, and i bands with exposure times of 45-90 seconds. A total area of about 727.4 square degrees of the 90% skymap (GCN 42650) was observed, covering ~64% of the event localization. Additionally, ~7.5% skymap was covered in 30s g- and r-band exposures through the WFST wide-field survey (WFS) 6.35 hours after the merger event. The follow-up observation data were processed using the WFST pipeline. For images localized in WFS, image subtraction was performed using the WFST stacking images taken berfore the event as templates. The search for the counterpart of S251112cm was performed mainly through visual inspection based on the locations of nearby galaxies, considering the distance estimate of 93 +/- 27 Mpc (redshift ~ 0.02; the LIGO-Virgo-Kagra Collaboration, GCN 42690) and the uncertainty of the potential electromagnetic counterpart. All extragalactic transient candidates detected by WFST during follow-ups were reported to the IAU Transient Name Server (TNS). After excluding sources with pre-merger detections reported in TNS, only one candidate was found to be located near a galaxy with spectroscopic redshift below 0.045: AT2025aebp was first detected at 60992.93 (+1.3 days post-merger) with 21.5 +/- 0.1 mag in r-band, and the spectroscopic redshift of its possible host galaxy SDSS J103703.20+231142.2 is 0.043. Additionally, we report three other sources without pre-merger detections. These sources have possible host galaxies with SDSS DR16 photometric redshift (Csabai et al., 2007; Ahumada et al., 2019) less than 0.1: | AT Name | MJD | RA | Dec | Filter | Mag | Host | photoZ | |------------|-----------|----------|----------|--------|----------|--------------------------|------------| | AT2025aebk | 60992.86 | 156.5043 | 24.9277 | g | 21.8 ± 0.1 | SDSS J102601.47+245542.1 | 0.06 ± 0.02 | | AT2025aebl | 60992.92 | 152.3554 | 18.2025 | r | 21.4 ± 0.1 | SDSS J100925.32+181207.3 | 0.09 ± 0.03 | | AT2025aebq | 60992.94 | 172.3128 | 36.6438 | r | 21.4 ± 0.1 | SDSS J112914.78+363832.0 | 0.09 ± 0.03 | We also checked the aforementioned candidates reported through TNS and GCN Circulars (GCN 42658, GCN 42666, GCN 42677, GCN 42691, GCN 42707). Ten public sources were detected in our difference images. Difference photometric results are listed as follows: | AT Name | MJD | RA | Dec | Filter | Mag | |------------|-----------|----------|----------|--------|------------| | AT2025adjd | 60992.96 | 190.8110 | 56.8036 | r | 21.31 ± 0.04 | | AT2025adie | 60992.83 | 185.3958 | 56.5862 | g | 21.7 ± 0.1 | | AT2025adhu | 60992.83 | 181.8041 | 55.6536 | g | 21.4 ± 0.1 | | AT2025adtj | 60990.94 | 172.5489 | 38.6207 | r | 19.64 ± 0.03 | | AT2025adia | 60992.85 | 169.5689 | 35.9858 | g | 21.6 ± 0.1 | | AT2025adln | 60989.89 | 168.0373 | 30.42659 | g | 21.2 ± 0.2 | | AT2025adlk | 60989.93 | 159.2667 | 19.30616 | g | 20.1 ± 0.1 | | AT2025adic | 60989.89 | 169.5444 | 41.0946 | g | 21.8 ± 0.2 | | AT2025adtq | 60990.94 | 175.6142 | 34.0085 | r | 21.2 ± 0.1 | | AT2025adtk | 60990.93 | 174.3825 | 31.3606 | r | 18.98 ± 0.02 | We thank the WFST staff for supporting these observations. Subsequent WFST observations and a systematic search for potential transients are ongoing. View this GCN Circular online at https://gcn.nasa.gov/circulars/42722. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40785] GRB 251116C: Swift-XRT observations
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42721 SUBJECT: GRB 251116C: Swift-XRT observations DATE: 25/11/17 15:30:14 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P.A. Evans (U. Leicester), J.A. Kennea (PSU), E. Ambrosi (INAF-IASFPA) , A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), R. Brivio (INAF-OAB), D.N. Burrows (PSU), S. Campana (INAF-OAB), M. Capalbi (INAF-OAR), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V. D'Elia (SSDC & INAF-OAR), S. Dichiara (PSU), M. Ferro (INAF-OAB), A. Melandri (INAF-OAR), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M. Perri (SSDC & INAF-OAR), C. Salvaggio (INAF-OAB), T. Sbarrato (INAF-OAB), B. Sbarufatti (INAF-OAB), M.A. Williams (PSU) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the SVOM/ECLAIRs-detected source GRB 251116C, collecting 1.7 ks of Photon Counting (PC) mode data between T0+10 ks and T0+26 ks after the trigger. We have detected 2 sources. These have been automatically classified as follows: * 0 likely counterparts * 0 candidate counterparts * 2 uncatalogued X-ray sources * 0 known X-ray sources Uncatalogued X-ray sources -------------------------- Source 1 (SWIFT J222122.5-102045): ================================== RA (J2000.0): 335.3441 = 22 21 22.58 Dec (J2000.0): -10.3459 = -10 20 45.2 Error: 6.9 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 6.1 arcmin from the SVOM/ECLAIRs position. Mean rate: (7.3 [+3.1, -2.5])e-3 ct s^-1 Mean flux: (4.4 [+1.9, -1.5])e-13 erg cm^-2 s^-1 Peak rate: (7.3 [+3.1, -2.5])e-3 ct s^-1 Peak flux: (4.4 [+1.9, -1.5])e-13 erg cm^-2 s^-1 ECF: 6.06e-11 erg cm^-2 ct^-1 assuming NH=4.81e+20 cm^-2, gamma=0.94 determined from a spectral fit. XMM UL: 4.1e-12 erg cm^-2 s^-1, (0.3-10 keV) so the source is not above this 3-sigma upper limit. There is no evidence for fading. There is 1 2MASS object within the source's 3-sigma error radius. Source 2 (SWIFT J222052.1-102849): ================================== RA (J2000.0): 335.2172 = 22 20 52.13 Dec (J2000.0): -10.4803 = -10 28 49.1 Error: 5.8 (arcsec, radius, 90% confidence). Detect flag: POOR Distance: 5.1 arcmin from the SVOM/ECLAIRs position. Mean rate: (-1.0 +/- -1.0)e0 ct s^-1 Mean flux: (-4.3 +/- -4.3)e-11 erg cm^-2 s^-1 Peak rate: (2.4 [+1.9, -1.3])e-3 ct s^-1 Peak flux: (1.03 [+0.80, -0.57])e-13 erg cm^-2 s^-1 XMM UL: 4.7e-12 erg cm^-2 s^-1, (0.3-10 keV) so the source is not above this 3-sigma upper limit. There is no evidence for fading. All fluxes are 0.3-10 keV, observed. For all flux conversions and comparisons with catalogues and upper limits from other missions, we assumed a power-law spectrum with NH=3x10^20 cm^-2 and photon index (Gamma)=1.7 unless otherwise stated. The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/SVOM/SVOM_FIELD00051. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42721. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40784] LIGO/Virgo/KAGRA S251116en: Updated Sky localization
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42720 SUBJECT: LIGO/Virgo/KAGRA S251116en: Updated Sky localization DATE: 25/11/17 14:29:45 GMT FROM: Colm Talbot at Princeton University <talbotcolm(a)gmail.com> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) data around the time of the compact binary merger (CBC) candidate S251116en (GCN Circular 42708). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S251116en For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 792 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1928 +/- 496 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/42720. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40783] GRB 251117A: Fermi GBM Final Localization Correction
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42719 SUBJECT: GRB 251117A: Fermi GBM Final Localization Correction DATE: 25/11/17 13:55:50 GMT FROM: Elisabetta Bissaldi at Politecnico and INFN Bari <elisabetta.bissaldi(a)ba.infn.it> The Fermi GBM team reports the detection of a likely SHORT GRB. At 12:19:52.14 UT on 17 November 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251117A (trigger 785074797/251117514). This trigger was initially classified as Below horizon by the flight software, but is in fact due to a GRB. The on-ground calculated location, using the Fermi GBM trigger data, is RA = 335.05, Dec = 5.01 (J2000 degrees, equivalent to J2000 22h 20m, +05d 00'), with a statistical uncertainty of 4.40 degrees. The angle from the Fermi LAT boresight is 52 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251117514/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251117514/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251117514/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42719. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40782] GRB 251116D: Glowbug gamma-ray detection
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42718 SUBJECT: GRB 251116D: Glowbug gamma-ray detection DATE: 25/11/17 13:07:33 GMT FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung(a)nrl.navy.mil> C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 251116D, which was also detected by AstroSat/CZTI and Konus-Wind (GCN 42715). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-11-16 19:22:33.960 with a duration of 14.3 s and a total significance of about 60 sigma. The light curve comprises a primary peak at ~T0+2s, followed by a multi-peaked structure for the duration of the burst. The best-fit localization is RA, Decl. (J2000, deg) = 148.0, -37.6 with a radius of 3.7 deg (95% confidence), with a highly uncertain systematic uncertainty. The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42718. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40781] EP251023a: Assy AZT-20 optical observations
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42717 SUBJECT: EP251023a: Assy AZT-20 optical observations DATE: 25/11/17 13:07:17 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. Volnova (IKI), A. Pozanenko (IKI), M. Krugov (FAI) report on behalf of IKI-GRB-FuN: We observed the field of the EP transient EP251023a (Wu et al., GCN 42388) in r' filter with the AZT-20 1.5m telescope of Assy-Turgen observatory starting on Oct., 23, 2025 (UT) 20:25:35, taking several exposures of 60 seconds. The optical counterpart (Wortley et al., GCN 42387; Li et al., GCN 42389; Liu et al., GCN 42391; Mandarakas et al., GCN 42400; Lipunov et al., GCN 42405; Selezneva et al., GCN 42406; Mohan et al., GCN 42411; Rakotondrainibe et al., GCN 42420; Rajabov et al., GCN 42422; Volnova et al., GCN 42468; Volnova et al., GCN 42716) is clearly detected in the stacked frame. The preliminary photometry is the following: Date UT start t-T0 Exp. Filter OT Err. UL (mid,days) (n*s) (3sigma) 2025-10-23 20:25:35 0.76378 30*60 r' 20.22 0.06 22.2 The photometry is based on several nearby PS1 stars (AB-system) and is not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/42717. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40780] EP251023a: ISON/UAFO and AbAO optical observations
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42716 SUBJECT: EP251023a: ISON/UAFO and AbAO optical observations DATE: 25/11/17 12:54:12 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. Volnova (IKI), A. Pozanenko (IKI), A. Kochergin (UAFO), R. Ya. Inasaridze (AbAO) report on behalf of IKI-GRB-FuN: We observed the field of the EP transient EP251023a (Wu et al., GCN 42388) with the RC-500 (0.5m) telescope of UAFO/ISON-Ussuriysk observatory on Oct., 23, 2025 starting at (UT) 17:51:51, and the AS-32 0.7m telescope of the Abastumani Observatory (AbAO) on Oct., 24, 2025, starting at (UT) 22:53:36. Several 60-second exposures in R-filter were obtained during each observational epoch. The optical counterpart (Wortley et al., GCN 42387; Li et al., GCN 42389; Liu et al., GCN 42391; Mandarakas et al., GCN 42400; Lipunov et al., GCN 42405; Selezneva et al., GCN 42406; Mohan et al., GCN 42411; Rakotondrainibe et al., GCN 42420; Rajabov et al., GCN 42422; Volnova et al., GCN 42468) is clearly detected in the stacked UAFO image and is not detected in that of the AbAO. The preliminary photometry is the following: Date UT start t-T0 Exp. Filter OT Err. UL Site/Tel. (mid,days) (n*s) (3sigma) 2025-10-23 17:51:51 0.67889 100*60 R 19.97 0.22 20.9 UAFO/RC-500 2025-10-24 22:53:36 1.88138 40*60 R n/d n/d 20.5 AbAO/AS-32 The photometry is based on several nearby PS1 stars (Lupton's R-band transformation, Vega system) and is not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/42716. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40779] GRB 251116D: AstroSat CZTI detection
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42715 SUBJECT: GRB 251116D: AstroSat CZTI detection DATE: 25/11/17 10:04:03 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> Harsha K. H. (IUCAA), S. Salunke (IUCAA), M. Tembhurnikar (IUCAA), A. Goyal (IITB), A. Arya (IITB), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 251116D which was also detected by Konus Wind (IPN Notices). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2025-11-16 19:22:37.50 UTC. The measured peak count rate associated with the burst is 472 (+45, -48) counts/s above the background in the combined data of all quadrants, with a total of 2912 (+187, -203) counts. The local mean background count rate was 283 (+3, -3) counts/s. Using cumulative rates, we measure a T90 of 12.4 (+1.5, -0.8) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2025-11-16 19:22:36.63 UTC. The measured peak count rate associated with the burst is 1074 (+80, -86) counts/s above the background in the combined data of all quadrants, with a total of 4561 (+353, -380) counts. The local mean background count rate was 1330 (+6, -7) counts/s. We measure a T90 of 12.0 (+1.0, -1.4) s from the cumulative Veto light curve. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/42715. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40778] LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42714 SUBJECT: LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations DATE: 25/11/17 09:58:25 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Q. Y. Wu, J. W. Hu, Y. Liu (NAO, CAS), B. Zhang (HKU) on behalf of the Einstein Probe (EP) team: EP-FXT performed a series of follow-up observations of the LIGO/Virgo/KAGRA gravitational-wave event S251112cm (GCN 42650, GCN 42690), with 100 galaxy-targeted observations have been completed. These observations were conducted from 2025-11-12T15:38:36 to 2025-11-14T10:28:28 (UTC), with each pointing having an exposure of approximately 300 s. EP-FXT covered 88 deg2 (8.9% in probability) of the updated sky localization area (GCN 42690) We cross-matched all FXT detections from these pointings against the updated list of NED galaxies provided in GCN 42693, using a 100″ matching radius (for a galaxy at 100 Mpc this corresponds to an offset of ~50 kpc). Most matched sources have prior X-ray detections with FXT fluxes comparable to historical values. There are two weak sources without prior X-ray counterparts within the FXT error region. Their information is summarized below (RA/Dec in degrees with 10" error radius (90% C.L.); fluxes are the observed ones in 0.5–10 keV): Name | RA | Dec | Matched NED Galaxy | Sep. (arcsec) | Flux (erg/s/cm^2) | SNR ---------------------------------------------------------------------------------------------------------------------------- EPF_J234847.8-282639 | 357.1990 | -28.4442 | WISEA J234841.30-282641.1 | 85.2 | 7.4e-13| 6.6 EPF_J010845.7-463304 | 17.1904 | -46.5512 | SMDG J0108452-463428 | 83.8 | 1.4e-13| 4.2 In addition, FXT detected 8 sources with no prior X-ray detections, no matches to the NED galaxies and no obvious AGN or stellar counterparts within the FXT error regions. Their information is summarized below (RA/Dec in degrees with 10" error radius (90% C.L.); fluxes are the observed ones in 0.5–10 keV): Name | RA | Dec | Flux (erg/s/cm^2) | SNR ------------------------------------------------------------------------- EPF_J000245.6-341925 | 0.6899 | -34.3235 | 2.0e-13| 4.0 EPF_J020544.2-520424 | 31.4343 | -52.0734 | 1.7e-13| 4.1 EPF_J092041.9-081815 | 140.1746 | -8.3041 | 2.1e-13| 4.9 EPF_J093255.2-020027 | 143.2301 | -2.0076 | 4.3e-13| 3.5 EPF_J111043.0+362227 | 167.6792 | 36.3742 | 1.6e-13| 4.6 EPF_J113825.2+432218 | 174.6051 | 43.3716 | 7.3e-14| 5.4 EPF_J232328.1-114600 | 350.8670 | -11.7667 | 1.5e-13| 3.9 EPF_J234628.3-290057 | 356.6177 | -29.0158 | 7.9e-13| 4.5 Further FXT observations of these candidates will be conducted. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/42714. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40777] The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42713 SUBJECT: The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations DATE: 25/11/17 09:56:34 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. Volnova (IKI), E. Klunko (ISTP), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We observed the field of the EP-WXT trigger 01709247588 (Feng et al., GCN 42510) with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy) in the R-filter starting Oct., 29, 2025, UT 16:48:48, and taking several frames with 120 s exposures. The Emission-line Star PM J04472+2038 likely associated with the transient is clearly detected and not saturated. Preliminary photometry and observational details are the following: Date UT start MJD Exp. Filter Star Err. UL (mid) (n*s) (3sigma) 2025-10-29 16:48:48 60977.71098 15*120 R 13.25 0.08 22.2 The photometry is based on several nearby USNO-B1.0 stars (R2-magnitudes) and is not corrected for the Galactic extinction, all magnitudes are in Vega system. The star PM J04472+2038 is at least 0.4 mag brighter in our observations comparing to USNO-B1.0 and UCAC catalogues: UCAC R = 13.99 +/- 0.09, USNO-B1.0 R1 = 13.65, R2 = 14.07. This 0.4m brightness increase 5.5 hours after the EP-WXT trigger may confirm the connection between EP-WXT 01709247588 and the stellar flare. View this GCN Circular online at https://gcn.nasa.gov/circulars/42713. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40776] GRB 251116C: SVOM/VT optical upperlimit
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42712 SUBJECT: GRB 251116C: SVOM/VT optical upperlimit DATE: 25/11/17 09:39:51 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Y. N. Ma, Z. H. Yao, Y. Xu, X. H. Han, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. R. Xu, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA), M. Pillas (IAP), M.G. Bernardini (INAF-OAB, LUPM) report on behalf of the SVOM/VT team. SVOM/VT performed an automatic slew on GRB 251116C (SVOM burst-id sb25111605, Pillas et al., GCN 42703). The observation started on 2025-11-16T17:04:52 UT (i.e. 1.1 hour post trigger) in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. No uncatalogued sources are detected in single or stacked images within ECL's error box (Pillas et al., GCN 42703) and the Swift/XRT source #1 and source #2's error box (https://www.swift.ac.uk/SVOM/SVOM_FIELD00051/) The 3 sigma limit magnitudes are derived as below: Mid time | Band | Exposure Time | 3 sigma limit magnitude 1.4 hour VT_B 23*50 sec >23.3 mag 1.4 hour VT_R 28*50 sec >23.4 mag Our result is consistent with the LCO's observation (Turpin et al., GCN 42705). The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS. View this GCN Circular online at https://gcn.nasa.gov/circulars/42712. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40775] GRB 251025B: further Mondy optical observations
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42711 SUBJECT: GRB 251025B: further Mondy optical observations DATE: 25/11/17 08:08:51 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. Volnova (IKI), E. Klunko (ISTP), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We continued observations of the field of the GRB 251025B (Hussein et al., GCN 42437) in the R-filter with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy) taking several frames with 120 s exposures on Oct. 27-29 and Nov. 1, 2025. The optical counterpart (Wu et al., GCN 42438; Gress et al., GCN 42439; Wu et al., GCN 42440; Beardmore et al., GCN 42445; Mohan et al., GCN 42447; Hernández Funget al., GCN 42450; Pereyra et al., GCN 42452; Li et al., GCN 42453; Mo et al., GCN 42459; Rakotondrainibe et al., GCN 42460; Rajabov et al., GCN 42466; Saccardi et al., GCN 42472; Freeberg et al., GCN 42474; Volnova et al., GCN 42475; Gupta et al., GCN 42500; Mohan et al., GCN 42503; Adami et al., GCN 42547) is clearly detected in the stacked frame of every epoch. Preliminary photometry is the following: Date UT start t-T0 Exp. Filter OT Err. UL (mid,days) (n*s) (3sigma) 2025-20-27 15:53:18 2.08280 30*120 R 21.22 0.07 22.8 2025-10-28 16:11:51 3.11396 29*120 R 21.82 0.17 22.3 2025-10-29 15:14:24 4.03841 5*120 R 21.95 0.25 22.2 2025-11-01 15:12:37 7.07680 60*120 R 22.94 0.26 23.2 The photometry is based on several nearby SDSS stars (R-magnitudes Lupton's transformation) and is not corrected for the Galactic extinction, all magnitudes are in Vega system. View this GCN Circular online at https://gcn.nasa.gov/circulars/42711. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40774] GRB 251111A: Mondy optical upper limit
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42710 SUBJECT: GRB 251111A: Mondy optical upper limit DATE: 25/11/17 08:05:29 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> A. Volnova (IKI), E. Klunko (ISTP), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We observed the field of the GRB 251111A (Cheng et al., GCN 42637) with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy) in the R-filter starting Nov., 11, 2025, UT 16:26:22, and taking several frames with 120 s exposures. In the stacked frame we do not detect the optical counterpart (López-Cámara et al., GCN 42638; Wu et al., GCNs 42639, 42641; Ma et al., GCN 42647). Preliminary photometry is the following: Date UT start t-T0 Exp. Filter OT Err. UL (mid,days) (n*s) (3sigma) 2025-11-11 16:26:22 0.48686 25*120 R n/d n/d 22.1 The photometry is based on several nearby SDSS stars (R-magnitudes Lupton's transformation) and is not corrected for the Galactic extinction, all magnitudes are in Vega system. View this GCN Circular online at https://gcn.nasa.gov/circulars/42710. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40773] GRB 251116B: EP-FXT follow-up observation
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42709 SUBJECT: GRB 251116B: EP-FXT follow-up observation DATE: 25/11/17 03:44:02 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> D.Y. Li, G. J. Yang, C. L. Guo (NAO, CAS), D. Z. Du (ZJU), R. X. Hu (WHU), Q. J. Huang(PMO, CAS), Y. Liu (NAO, CAS) on behalf of the Einstein Probe (EP) team: EP-FXT performed a follow-up observation of the SVOM/ECLAIRs-detected burst GRB 251116B (SVOM/sb25111604, Pillas et al., GCN #42702) at 2025-11-16 17:13:25 (UTC), about 1.7 hours after the SVOM/ECLAIRs trigger, with an exposure time of 5832s. Six uncataloged sources are detected within the ECLAIRs error circle. Preliminary analysis on these sources is automatically conducted, and the details are listed as follows. EPF_J011551.9-410700 RA (J2000): 18.9664 Dec (J2000): -41.1167 Flux: 5.54 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 1.68 x 10^-14 erg/s/cm2 (1 sigma) EPF_J011518.5-405816 RA (J2000): 18.8272 Dec (J2000): -40.971 Flux: 1.35 x 10^-13 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 4.97 x 10^-14 erg/s/cm2 (1 sigma) EPF_J011442.3-410511 RA (J2000): 18.6761 Dec (J2000): -41.0863 Flux: 4.54 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 1.58 x 10^-14 erg/s/cm2 (1 sigma) EPF_J011604.1-410246 RA (J2000): 19.0172 Dec (J2000): -41.0461 Flux: 6.74 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 1.73 x 10^-14 erg/s/cm2 (1 sigma) EPF_J011523.3-410250 RA (J2000): 18.8471 Dec (J2000): -41.0471 Flux: 6.72 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 2.29 x 10^-14 erg/s/cm2 (1 sigma) EPF_J011535.7-410502 RA (J2000): 18.8988 Dec (J2000): -41.0839 Flux: 7.66 x 10^-14 erg/s/cm2 (observed, 0.5-10 keV) Flux_err: 1.59x 10^-14 erg/s/cm2 (1 sigma) View this GCN Circular online at https://gcn.nasa.gov/circulars/42709. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40772] LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
by GCN Circulars 17 Nov '25

17 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42708 SUBJECT: LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate DATE: 25/11/17 00:04:59 GMT FROM: Jyotirmaya Mohanta at University of Tsukuba <s2430161(a)u.tsukuba.ac.jp> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S251116en during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2025-11-16 23:22:21.761 UTC (GPS time: 1447370559.761). The candidate was found by the Aframe [1], cWB [2], cWB BBH [3], GstLAL [4], MBTA [5], MLy [6], PyCBC Live [7], and SPIIR [8] analysis pipelines. S251116en is an event of interest because its false alarm rate, as estimated by the online analysis, is 1.3e-12 Hz, or about one in 1e4 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S251116en The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), BNS (<1%), or NSBH (<1%). Assuming the candidate is astrophysical in origin, the probability that at least one of the compact objects is consistent with a neutron star mass (HasNS) is <1%. [9] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [9] Both HasNS and HasRemnant consider the support of several neutron star equations of state for maximum neutron star mass. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is <1%. The source chirp mass falls with highest probability in the bin (22.0, 44.0) solar masses, assuming the candidate is astrophysical in origin. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * amplfi.multiorder.fits,0, an initial localization generated by AMPLFI [10], distributed via GCN and SCiMMA notices about 25 seconds after the candidate event time. * bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [11], distributed via GCN and SCiMMA notices about 4 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,0. For the bayestar.multiorder.fits,0 sky map, the 90% credible region is 788 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1741 +/- 490 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Marx et al. PRD 111, 042010 (2025) doi:10.1103/PhysRevD.111.042010 [2] Klimenko et al. PRD 93, 042004 (2016) doi:10.1103/PhysRevD.93.042004 [3] T. Mishra et al. PRD 105, 083018 (2022) doi:10.1103/PhysRevD.105.083018 [4] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. PRD 109, 042008 (2024) doi:10.1103/PhysRevD.109.042008 [5] Alléné et al. CQG 42, 105009 (2025) doi:10.1088/1361-6382/add234 [6] Skliris et al. PRD 110, 104034 (2024) doi:10.1103/PhysRevD.110.104034 [7] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a [8] Chu et al. PRD 105, 024023 (2022) doi:10.1103/PhysRevD.105.024023 [9] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [10] Chatterjee et al. MLST 5, 045030 (2024) doi:10.1088/2632-2153/ad8982 [11] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/42708. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40771] LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
by GCN Circulars 16 Nov '25

16 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42707 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory DATE: 25/11/16 23:22:33 GMT FROM: Sean MacBride at University of Zurich <sean.p.macbride(a)gmail.com> Sean MacBride (University of Zurich), Erin Howard, Ian Sullivan, Peter Yoachim, Eric Bellm (University of Washington), Shreya Anand (Stanford University), Federica Bianco (University of Delaware), Tiago Ribeiro, Lynne Jones, Alysha Shugart, Narayan Khadka, Kshitija Kelkar, Danica Zilkova, Kevin Fanning, Paulina Venegas, Kate Napier, Erik Dennihy, Anastasia Alexov, Bob Blum (NSF-DOE Vera C Rubin Observatory), Yousuke Utsumi (National Astronomical Observatory of Japan), Robert Lupton (Princeton University), Keith Bechtol (University of Wisconsin-Madison), reporting on behalf of NSF-DOE Vera C Rubin Observatory: We observed the localization region of the sub-solar mass merger S251112cm, reported by LIGO/Virgo/KAGRA (GCN 42650, GCN 42690) with the 9.6 square degree field of view LSST Camera mounted on the 8.4-m Simonyi Survey Telescope at the Vera C. Rubin Observatory. As reported in GCN 42690, S251112cm has a reported 90% localization area of 1681 square degrees and an expected false alarm rate of approximately one in four years. This is the first Target-of-Opportunity observation with Rubin Observatory since the transition to operations in late October 2025. Rubin Observatory is in an early operations period of continued system optimization, prior to beginning sustained LSST observations [1]. During this period, data quality and acquisition rate are variable. Not all data products that will be available during the Legacy Survey of Space and Time (LSST) operations are currently available [2]. Observations were conducted through engagement of the new Rubin Target-of-Opportunity advisory board, as a sub-solar mass merger does not meet the typical alert quality criteria for Rubin Target-of-Opportunity (ToO) observation [3]. The observing strategy for this event is to image the localization area in LSST g and i bands, with one 30 second visit for each band, on nights 0, 2, 4, and 6 of the observing campaign. On November 15 2025, at 01:49:27 UTC, we began observing the localization region of S251112cm, using the initial localization information provided in GCN 42650. We observed 39.2% (849.1 deg^2) of the localization area in the g-band, and 33.5% (754.9 deg^2) of the localization area in the i band. The difference in coverage was due to the localization area of S251112cm setting early in the night in Chile, before the telescope could observe the region in i band. For these observations, we reached a median depth of 24.8 mag in g band, 23.7 mag in the i band. Due to the lack of prior Rubin observations in most of the imaging area, we performed image differencing against DECam templates. To support the usage of DECam templates, we devised a custom image processing task to create DECam templates from DES templates for use with LSSTCam observations. Apart from the DECam template task, we utilize the standard LSST data release production pipeline to obtain difference images and photometry on difference image sources [4]. With only a single epoch of observations at Rubin Observatory, we are unable to characterize viable candidates from Rubin observations alone. Here, we report on candidates reported in GCN 42658, 42663, 42666, 42675, 42677, 42681, 42682, and 42691. We do not recover several candidates from these GCN’s for one of many reasons: lack of signal in the difference images, poor image subtraction near the source, or a lack of imaging in the region. Here, we report the candidates that pass these criteria, and comment on any notable nearby galaxies, given the reported luminosity distance from LVK (GCN 42650). We perform visual inspection on difference images that are coincident with previously reported candidates. We positively detect AT2025adgq, AT2025adhf, AT2025adkl, AT2025adjp, and AT2025addc. AT2025adhf and AT2025adkl were only detected unambiguously in one band (g and i respectively). Whether they are not detected in the other band is still under investigation.. AT2025adgq is detected unambiguously in two bands, separated from a host galaxy by ~10 arcseconds. AT2025adhf is nuclear to a barred spiral galaxy (WISEA J024344.38-551906.1), but its WISE colors are not consistent with the host being an AGN. AT2025adkl is offset by 90’ from a galaxy within the NED volume (GCN 42653), slightly offset from a small distant galaxy, and detected unambiguously in one band. AT2025adjp and AT2025addc are isolated sources detected unambiguously in two bands. Here we report difference photometry for the aforementioned candidates: | AT Name | Observation Date [UTC] | RA | Dec | g | unc_g | i | unc_i | |------------|------------------------|---------|----------|-------|-------|-------|-------| | AT2025adgq | 2025-11-15 | 7.3825 | -39.5143 | 19.55 | 0.005 | 19.52 | 0.003 | | AT2025adhf | 2025-11-15 | 40.9351 | -55.3184 | - | - | 19.21 | 0.004 | | AT2025adkl | 2025-11-15 | 7.5357 | -41.0787 | 21.58 | 0.014 | - | - | | AT2025adjp | 2025-11-15 | 4.5396 | -33.8543 | 21.17 | 0.010 | 20.90 | 0.016 | | AT2025addc | 2025-11-15 | 73.8589 | -53.1621 | 20.91 | 0.009 | 21.25 | 0.022 | Analysis of these candidates is ongoing. We will continue to observe the localization area of S251112cm in the coming days according to the observing plan. We thank all who contributed to the design and implementation of the Vera C. Rubin Observatory Target-of-Opportunity system, including but not limited to, the LSST Transients and Variable Stars Science Collaboration Multiwavelength Characterization and Counterparts subgroup. We especially thank the Rubin Observatory observers, who are instrumental to the performance and success of the LSST. This material is based upon work supported in part by the National Science Foundation through Cooperative Agreements AST-1258333 and AST-2241526 and Cooperative Support Agreements AST-1202910 and 2211468 managed by the Association of Universities for Research in Astronomy (AURA), and the Department of Energy under Contract No. DE-AC02-76SF00515 with the SLAC National Accelerator Laboratory managed by Stanford University. Additional Rubin Observatory funding comes from private donations, grants to universities, and in-kind support from LSST-DA Institutional Members. [1] sitcomtn-005.lsst.io, §6 [2] lse-163.lsst.io [3] www.inspirehep.net/literature/2846480 [4] pstn-019.lsst.io View this GCN Circular online at https://gcn.nasa.gov/circulars/42707. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40770] GRB 251116B: LCO optical upper limits
by GCN Circulars 16 Nov '25

16 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42706 SUBJECT: GRB 251116B: LCO optical upper limits DATE: 25/11/16 20:59:01 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> D. Turpin, A. Saccardi, J. T. Palmerio (CEA/Irfu), L. P. Xin, C. Wu (NAOC), B. Cordier (CEA/Irfu), M. Pillas (IAP), M.G. Bernardini (INAF-OAB, LUPM), report on behalf of the SVOM mission team: We observed the field of GRB 251116B (Pillas et al., GCN 42702) with the LCO 1m telescope at the South African Astronomical Observatory (SAAO) equipped with the Sinistro instrument. Our observation started at 2025-11-16T18:42:46, about 3.1 hours after the SVOM/ECLAIRs trigger time. We obtained 3x200 s exposures in the SDSS r and the Pan-STARRS z filters. No uncatalogued source was identified in our stacked frames after subtraction against the Legacy Survey DR10 catalog image. We measure the following upper limits (5 sigma) calibrated against the SkyMapper DR4 catalog, and not corrected for Galactic extinction: r = 22.1 (AB) T_mid - T0 = 3.26 hr z = 20.1 (AB) T_mid - T0 = 3.98 hr This project is funded by the SVOM collaboration. View this GCN Circular online at https://gcn.nasa.gov/circulars/42706. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40769] GRB 251116C: LCO optical upper limits
by GCN Circulars 16 Nov '25

16 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42705 SUBJECT: GRB 251116C: LCO optical upper limits DATE: 25/11/16 20:07:59 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> D. Turpin, A. Saccardi, J. T. Palmerio (CEA/Irfu), L. P. Xin (NAOC), C. Wu (NAOC), B. Cordier (CEA/Irfu), M. Pillas (IAP), M.G. Bernardini (INAF-OAB, LUPM), report on behalf of the SVOM mission team: We observed the field of GRB 251116C (Pillas et al., GCN 42703) with the LCO 1m telescope at the South African Astronomical Observatory (SAAO) equipped with the Sinistro instrument. Our observation started at 2025-11-16T18:45:47 about 2.8 hours after the SVOM/ECLAIRs trigger time. We obtained 3x200 s exposures in the SDSS r and 3x200s exposures in the PanSTARRS z filters. No any uncatalogued source was identified in our stacked frames. We measure the following upper limits (5 sigma) calibrated against the PanSTARRS DR1 catalog, and not corrected for Galactic extinction: r = 21.5 (AB) T_mid - T0 = 3.1 hr z = 19.9 (AB) T_mid - T0 = 2.9 hr This project is funded by the SVOM collaboration. View this GCN Circular online at https://gcn.nasa.gov/circulars/42705. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40768] SVOM GRB251116.66: Global MASTER-Net observations report
by GCN Circulars 16 Nov '25

16 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42704 SUBJECT: SVOM GRB251116.66: Global MASTER-Net observations report DATE: 25/11/16 16:56:29 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Tunka robotic telescope [1] located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the SVOM GRB251116.66 (trigger No 1763308636,22h 21m 03.65s , -10d 24m 37.8s, R=0.1302) errorbox 25 sec after notice time and 310 sec after trigger time at 2025-11-16 16:02:26 UT, with upper limit up to 13.6 mag. The observations began at zenith distance = 83 deg. The sun altitude is -56.4 deg. The galactic latitude b = -51 deg., longitude l = 52 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3043922 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 341 | 2025-11-16 16:02:26 | MASTER-Tunka | (22h 21m 03.35s , -10d 19m 13.2s) | P- | 60 | 13.6 | 341 | 2025-11-16 16:02:26 | MASTER- | (22h 20m 46.89s , -10d 14m 22.2s) | C | 60 | 16.6 | 404 | 2025-11-16 16:03:30 | MASTER-Tunka | (22h 21m 03.18s , -10d 19m 14.1s) | P- | 60 | 13.3 | 405 | 2025-11-16 16:03:30 | MASTER- | (22h 20m 45.91s , -10d 14m 11.5s) | C | 60 | 16.6 | 468 | 2025-11-16 16:04:33 | MASTER-Tunka | (22h 21m 03.13s , -10d 19m 13.7s) | P- | 60 | 13.4 | 468 | 2025-11-16 16:04:33 | MASTER- | (22h 20m 45.80s , -10d 14m 11.6s) | C | 60 | 16.4 | 532 | 2025-11-16 16:05:37 | MASTER-Tunka | (22h 21m 03.20s , -10d 19m 09.1s) | P- | 60 | 13.5 | 532 | 2025-11-16 16:05:37 | MASTER- | (22h 20m 45.69s , -10d 14m 13.4s) | C | 60 | 16.3 | 596 | 2025-11-16 16:06:42 | MASTER-Tunka | (22h 21m 02.88s , -10d 19m 13.7s) | P- | 60 | 13.0 | 596 | 2025-11-16 16:06:42 | MASTER- | (22h 20m 45.81s , -10d 14m 10.6s) | C | 60 | 16.3 | 660 | 2025-11-16 16:07:45 | MASTER-Tunka | (22h 21m 02.81s , -10d 19m 14.0s) | P- | 60 | 13.3 | 723 | 2025-11-16 16:08:49 | MASTER-Tunka | (22h 21m 02.83s , -10d 19m 13.6s) | P- | 60 | 13.1 | 723 | 2025-11-16 16:08:49 | MASTER- | (22h 20m 45.60s , -10d 14m 12.6s) | C | 60 | 16.3 | 794 | 2025-11-16 16:09:59 | MASTER-Tunka | (22h 21m 02.55s , -10d 19m 16.7s) | P- | 60 | 13.0 | 794 | 2025-11-16 16:09:59 | MASTER- | (22h 20m 45.36s , -10d 14m 16.4s) | C | 60 | 16.3 | 857 | 2025-11-16 16:11:03 | MASTER-Tunka | (22h 21m 02.58s , -10d 19m 14.6s) | P- | 60 | 12.3 | 857 | 2025-11-16 16:11:03 | MASTER- | (22h 20m 45.53s , -10d 14m 12.8s) | C | 60 | 16.2 | 921 | 2025-11-16 16:12:07 | MASTER-Tunka | (22h 21m 02.72s , -10d 19m 10.5s) | P- | 60 | 13.1 | 921 | 2025-11-16 16:12:07 | MASTER- | (22h 20m 44.78s , -10d 14m 31.2s) | C | 60 | 16.3 | 985 | 2025-11-16 16:13:10 | MASTER-Tunka | (22h 21m 02.34s , -10d 19m 15.4s) | P- | 60 | 12.5 | 1068 | 2025-11-16 16:14:34 | MASTER-Tunka | (22h 21m 02.35s , -10d 19m 11.9s) | P- | 60 | 12.7 | 1132 | 2025-11-16 16:15:37 | MASTER-Tunka | (22h 21m 02.11s , -10d 19m 15.6s) | P- | 60 | 12.4 | 1132 | 2025-11-16 16:15:37 | MASTER- | (22h 20m 43.68s , -10d 14m 23.0s) | C | 60 | 16.2 | 1195 | 2025-11-16 16:16:41 | MASTER-Tunka | (22h 21m 01.96s , -10d 19m 17.1s) | P- | 60 | 12.0 | 1322 | 2025-11-16 16:18:48 | MASTER-Tunka | (22h 21m 01.71s , -10d 19m 17.4s) | P- | 60 | 12.0 | 1323 | 2025-11-16 16:18:48 | MASTER- | (22h 20m 43.97s , -10d 14m 36.1s) | C | 60 | 15.9 | 1386 | 2025-11-16 16:19:51 | MASTER-Tunka | (22h 21m 01.46s , -10d 19m 21.7s) | P- | 60 | 12.0 | 1450 | 2025-11-16 16:20:55 | MASTER-Tunka | (22h 21m 01.38s , -10d 19m 19.5s) | P- | 60 | 12.3 | 1577 | 2025-11-16 16:23:02 | MASTER-Tunka | (22h 21m 01.10s , -10d 19m 17.9s) | P- | 60 | 12.3 | 1641 | 2025-11-16 16:24:06 | MASTER-Tunka | (22h 21m 01.02s , -10d 19m 18.5s) | P- | 60 | 12.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42704. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40767] GRB 251116C: SVOM detection of a burst
by GCN Circulars 16 Nov '25

16 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42703 SUBJECT: GRB 251116C: SVOM detection of a burst DATE: 25/11/16 16:22:19 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> M. Pillas (IAP), M.G. Bernardini (INAF-OAB, LUPM), M. Brunet (IRAP), A. Saccardi (CEA/Irfu), report on behalf of the SVOM mission team: At 2025-11-16T15:57:41 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251116C (SVOM burst-id sb25111605). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 3 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 12.47 in the [5-20] keV energy band over a time window of 40.96 seconds starting at 2025-11-16T15:57:36. The localization of the best alert is R.A., Dec. 335.3182, -10.4239 degrees: R.A. (J2000) = 22h21m16.37s Dec. (J2000) = -10d25m26.01s with a 90% confidence level (C.L.) radius of 6.49 arcmin (including systematic error of 2 arcmin added in quadrature). SVOM slewed to the burst. No X-ray observation could be performed by SVOM/MXT for the time being. No optical observation could be performed by SVOM/VT for the time being. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Marion Pillas: marion.pillas(a)iap.fr. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42703. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40766] GRB 251116B: SVOM detection of a burst
by GCN Circulars 16 Nov '25

16 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42702 SUBJECT: GRB 251116B: SVOM detection of a burst DATE: 25/11/16 16:10:05 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> M. Pillas (IAP), M.G. Bernardini (INAF-OAB, LUPM), M. Brunet (IRAP), report on behalf of the SVOM mission team: At 2025-11-16T15:32:36 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251116B (SVOM burst-id sb25111604). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was only detected by the Count-Rate Trigger (CRT), which produced a sequence of 1 alert. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 6.67 in the [8-120] keV energy band over a time window of 10.20 seconds starting at 2025-11-16T15:32:26. The localization of the best alert is R.A., Dec. 18.8320, -41.0854 degrees: R.A. (J2000) = 1h15m19.68s Dec. (J2000) = -41d05m07.42s with a 90% confidence level (C.L.) radius of 11.72 arcmin (including systematic error of 2 arcmin added in quadrature). Due to the detection significance being below the slew threshold, no immediate slew was performed on this burst. Further observations by SVOM/VT are currently scheduled. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Marion Pillas: marion.pillas(a)iap.fr. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42702. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40765] IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 16 Nov '25

16 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42701 SUBJECT: IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube DATE: 25/11/16 03:42:55 GMT FROM: Sam Hori at IceCube/U Wisc-Madison <sahori(a)wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-Cascade 251112A (https://gcn.gsfc.nasa.gov/notices_amon_icecube_cascade/141589_6342606.amon) in a time range of 1000 seconds centered on the alert event time (2025-11-12 16:25:42.310 UTC to 2025-11-12 16:42:22.310 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, 3 track-like events are found within the 90% containment region of IceCube-Cascade 251112A. We find that these additional 3 events are well described by atmospheric background expectations, with a p-value of 0.97. IceCube’s sensitivity to neutrino point sources with an E^-2.5 spectrum, expressed as E^2 dN/dE evaluated at 1 TeV, ranges from 1.3e-01 to 2.4e+01 GeV cm^-2 within the 90% spatial containment region of IceCube-Cascade 251112A in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 2e+02 GeV and 4e+06 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2025-11-11 16:34:02.310 UTC to 2025-11-13 16:34:02.310 UTC). In this case, we report a p-value of 0.21, consistent with no significant excess of track events. IceCube’s sensitivity to neutrino point sources with an E^-2.5 spectrum, expressed as E^2 dN/dE evaluated at 1 TeV, ranges from 1.5e-01 to 2.5e+01 GeV cm^-2 within the 90% spatial containment region of IceCube-Cascade 251112A in a 2 day time window. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu. [1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021) View this GCN Circular online at https://gcn.nasa.gov/circulars/42701. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40764] GRB 251116A: Fermi GBM Final Real-time Localization
by GCN Circulars 16 Nov '25

16 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42700 SUBJECT: GRB 251116A: Fermi GBM Final Real-time Localization DATE: 25/11/16 02:10:44 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 02:00:04 UT on 16 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251116A (trigger 784951209.245526 / 251116083). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 27.3, Dec = -24.8 (J2000 degrees, equivalent to J2000 01h 49m, -24d 48'), with a statistical uncertainty of 4.5 degrees. The angle from the Fermi LAT boresight is 30.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251116083/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251116083/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251116083/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42700. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40763] LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42699 SUBJECT: LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap DATE: 25/11/15 21:10:03 GMT FROM: antier(a)ijclab.in2p3.fr P. Hello (IJCLAB), D. Akl (NYUAD), S. Antier (IJCLAB), A. Klotz (IRAP), M. Mazek (FZU), M. Pillas (IAP), O. Pyshna (Caltech), C. Andrade (UMN), M. Coughlin (UMN), C. Douzet (IJCLAB), S. Karpov (FZU), T. duLaz (Caltech), R. LeMontagner (IJCLAB), C. Limonta (OCA), Y. Rajabov (UBAI), D. Turpin (CEA-AIM) on behalf of the GRANDMA collaboration: We observed the S251112cm (Initial, as provided by GCN 42650, LVK collaboration) sky localization area with wide field telescopes TAROT/TRE, TAROT/TCH, TAROT/TCA, FRAM-FZU,together with the 60 cm telescope at Les Makes Observatory. Observations started at 2025-11-12 17:14 UTC, e.g 1h56 after the trigger time and during 14h. We used the SkyPortal application (skyportal.io) and associated services to monitor this observational campaign (Coughlin et al. 2018, 2023). Our sensivity map of the GW sky localization area has been computed using Pillas et al., 2025 and is accessible at https://grandma-owncloud.ijclab.in2p3.fr/index.php/s/TqGach7PpbM4d3K. We covered 22% of the Initial sky localization area (Bayestar, GCN 42650 LVK collaboration) and 16% of the Updated sky localization area (Bilby, GCN 2690, LVK collaboration). Preliminary analysis did not reveal any clear candidate that can be associated to the event (with limit magnitudes ranging from 17 to 21 mag in r-band at 5 sigma). We re-conducted a second epoch of observations the day after. All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2025). Images obtained were calibrated using the PanSTARRS DR1 catalog. We are currently investigating candidates reported by other collaborations. GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/) View this GCN Circular online at https://gcn.nasa.gov/circulars/42699. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40762] LIGO/Virgo/KAGRA S251112cm: AT2025adht follow-up at Maidanak observatory by GRANDMA
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42698 SUBJECT: LIGO/Virgo/KAGRA S251112cm: AT2025adht follow-up at Maidanak observatory by GRANDMA DATE: 25/11/15 13:54:03 GMT FROM: Yodgor Rajabov at UBAI <rajabov(a)astrin.uz> O. Burkhonov, Y. Rajabov, Y. Tillayev (UBAI), P. Hello (IJCLAB), A. Klotz (IRAP), M. Coughlin (UMN), S. Karpov (FZU), M. Pillas (IAP), M. Mazek (FZU ), S. Antier (IJCLAB), O. Pyshna (Caltech) on behalf of GRANDMA: We detected transient event 2025adht in RA_J2000=12:00:24.3431, Dec_J2000=+49:02:51.7 reported by (GCN 42677 Anand et al., Franz GCN 42675 et al.,). Observations were carried out at the 1.5-meter telescope Maidanak Observatory by using 4Kx4K SNUCAM CCD. All observations were taken using a Bessel R filter. The observations started at 2025-11-15T00:13:15 UTC and ended at 2025-11-15T00:40:17 UTC. A total of 6 CCD images with an exposure of 300 seconds were obtained. Despite the fact that this object is located far from the equator, we checked for the presence of small bodies in this region using the small body database from 14 November 2025. The check was negative. Cross-identification results indicated the same galaxy without any transient events: DSS J120024.56+490254.3, WISEA J120024.53+490254.1, and GALEXASC J120024.49+490252.9. We analyzed our data using our standard pipeline and with STDWeb/STDPipe (Karpov, 2025). We present stacked results after galaxy soustraction. MJD | DATE-OBS | MAG |M_ERR|U.L.|FILTER| Telescope| MAG system -------------------------------------------------------------------------------------- 60994.00920139 | 2025-11-15 00:29 | 21.54|0.1|22.10|R|UBAI/AZT-22|Vega, Gaia DR3 Which has an equivalent using PS1 of 21.64+/- 0.1 in sdssr using PS1 (color term 0.13). More observations are planned. GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/) Maidanak astronomical observatory (MAO) is an observational facility of the Ulugh Beg Astronomical Institute (UBAI), Uzbekistan Academy of Sciences (http://maidanak.uz/) View this GCN Circular online at https://gcn.nasa.gov/circulars/42698. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40761] GRB 251115A: Tiled Swift observations
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42697 SUBJECT: GRB 251115A: Tiled Swift observations DATE: 25/11/15 13:11:54 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a series of observations, tiled on the sky, of the Fermi/LAT GRB 251115A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/xrt_products/TILED_GRB00140 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. The probability of finding serendipitous sources, unrelated to the Fermi/LAT event is high: any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/42697. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40760] GRB 251115A: Fermi-LAT detection
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42696 SUBJECT: GRB 251115A: Fermi-LAT detection DATE: 25/11/15 12:51:17 GMT FROM: A. Holzmann Airasca at University of Trento and INFN Bari <a.holzmannairasca(a)unitn.it> E. Bissaldi (Politecnico and INFN Bari), A. Holzmann Airasca (UniTrento and INFN Bari), R. Gupta (NASA GSFC), T. Nymark (KTH), F. Longo (University and INFN, Trieste) and S. Lopez (CNRS / IN2P3) report on behalf of the Fermi-LAT Collaboration: On November 15, 2025, Fermi-LAT detected high-energy emission from GRB 251115A, which was also detected by Fermi-GBM (trigger 784869607 / 251115139, GCN 42692) and Global MASTER (GCN 42694). The best LAT on-ground location is found to be: RA, Dec = 330.18, -9.18 (J2000) with an error radius of 0.36 deg (90 % containment, statistical error only). This was 80 deg from the LAT boresight at the time of the GBM trigger (T0 = 03:20:02.67 UT). The data from the Fermi-LAT shows a significant increase in the event rate that is spatially and temporally correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval 0 - 600 s after the GBM trigger is (1.04 ± 0.34) E-5 ph/cm2/s. The estimated photon index above 100 MeV is -2.5 ± 0.4. The highest-energy photon is a 1.6 GeV event which is observed ~ 490 seconds after the GBM trigger. A Swift ToO has been approved for this burst. The Fermi-LAT point of contact for this burst is Tanja Kramer Nymark (tanjan(a)kth.se) The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. View this GCN Circular online at https://gcn.nasa.gov/circulars/42696. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40759] GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42695 SUBJECT: GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis DATE: 25/11/15 11:31:15 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Nicolas Dagoneau (CEA), Chen-Wei Wang (IHEP), Frédéric Piron (LUPM), Jean-Luc Atteia (IRAP) Using the event-by-event data downloaded through the X-band ground station, we report the preliminary ECLAIRs-GRM joint analysis of GRB 251013C (SVOM burst-id sb2525101311, GCN 42222) detected at T0 = 2025-10-13T17:39:42, which was also detected Fermi/GBM (GCN 42259). The refined analysis for ECLAIRs only was reported in GCN 42292. T90s are given in the table below for both ECLAIRs and GRM. | Instrument | Energy Range | T90 (s) | |-----------------|------------------|-----------------| | ECLAIRs | 4–120 keV | 19 (-2 / +5) s | | GRM | 50–300 keV | 13 (-1 / +4) s | The ECLAIRs-GRM joint time-averaged spectrum (T0-0.83 s to T0+17.70 s) in the 8-5000 keV energy range is best fitted by a power-law model with a photon index of 1.55 -0.03/+0.02. With this model, the total 10-1000 keV fluence is (4.58 +/- 0.18)e-06 erg/cm^2. From the likelihood profile of Epeak obtained by iteratively fitting a cutoff power-law model with a frozen Epeak parameter, we derived a 95% confidence level lower limit of approximately 480 keV, which is consistent with the value measured by Fermi (GCN 42259). With a redshift of z = 0.572 (GCN 42227), the burst isotropic energy Eiso (from 1 keV to 10 MeV in its rest frame) is 5.6e51 erg, which makes this GRB consistent with type I GRBs in the 'Amati' relation diagram (Amati et al. 2002). All the quoted errors are at the 68% confidence level. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs-GRM point of contact for this burst is: Nicolas Dagoneau (nicolas.dagoneau AT cea.fr). View this GCN Circular online at https://gcn.nasa.gov/circulars/42695. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40758] Fermi GRB 251115A: Global MASTER-Net observations report
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42694 SUBJECT: Fermi GRB 251115A: Global MASTER-Net observations report DATE: 25/11/15 04:30:41 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 251115A ( Fermi GBM team, GCN 42692) errorbox 41 sec after notice time and 74 sec after trigger time at 2025-11-15 03:21:17 UT, with upper limit up to 20.0 mag. The observations began at zenith distance = 64 deg. The sun altitude is -38.6 deg. The galactic latitude b = -47 deg., longitude l = 59 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3042754 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 80 | 2025-11-15 03:21:17 | MASTER-OAFA | (22h 03m 35.41s , -07d 54m 09.9s) | C | 10 | 18.6 | 101 | 2025-11-15 03:21:33 | MASTER-OAFA | (22h 03m 35.36s , -07d 54m 09.6s) | C | 20 | 19.0 | 141 | 2025-11-15 03:22:09 | MASTER-OAFA | (22h 12m 15.81s , -08d 11m 40.7s) | C | 30 | 19.4 | 178 | 2025-11-15 03:22:45 | MASTER-OAFA | (22h 12m 15.80s , -08d 11m 40.4s) | C | 30 | 19.4 | 219 | 2025-11-15 03:23:21 | MASTER-OAFA | (22h 12m 15.79s , -08d 11m 40.4s) | C | 40 | 19.5 | 270 | 2025-11-15 03:24:07 | MASTER-OAFA | (22h 12m 15.78s , -08d 11m 40.0s) | C | 50 | 19.7 | 331 | 2025-11-15 03:25:03 | MASTER-OAFA | (22h 12m 15.78s , -08d 11m 40.0s) | C | 60 | 19.8 | 658 | 2025-11-15 03:30:00 | MASTER-OAFA | (22h 18m 22.95s , -04d 21m 04.4s) | C | 120 | 20.0 | 794 | 2025-11-15 03:32:06 | MASTER-OAFA | (22h 18m 22.96s , -04d 21m 04.5s) | C | 140 | 20.0 | 955 | 2025-11-15 03:34:32 | MASTER-OAFA | (22h 18m 22.96s , -04d 21m 04.4s) | C | 170 | 20.0 | 1076 | 2025-11-15 03:37:28 | MASTER-OAFA | (22h 18m 22.99s , -04d 21m 04.2s) | C | 60 | 19.5 | 1141 | 2025-11-15 03:38:34 | MASTER-OAFA | (22h 18m 23.03s , -04d 21m 04.4s) | C | 60 | 19.5 | 1207 | 2025-11-15 03:39:39 | MASTER-OAFA | (22h 18m 23.03s , -04d 21m 04.4s) | C | 60 | 19.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42694. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40757] LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42693 SUBJECT: LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume DATE: 25/11/15 03:46:56 GMT FROM: David Cook at Caltech/IPAC-NED <dcook(a)ipac.caltech.edu> David O. Cook (Caltech/IPAC), Rick Ebert (Caltech/IPAC), George Helou (Caltech/IPAC), Joseph M. Mazzarella (Caltech/IPAC), Marion Schmitz (Caltech/IPAC), and Leo Singer (NASA/GSFC) On behalf of the NASA/IPAC Extragalactic Database (NED) Team. We spatially cross-matched the LVK S251112cm-4-Update sky localization with the NED Local Volume Sample (NED-LVS; Cook et al. 2023; https://ned.ipac.caltech.edu/NED::LVS/) which is a subset of NED with a redshift or redshift-independent distance less than 1000 Mpc. We find 9047 galaxies within the 90% containment volume, and we list here the top 20 galaxies sorted by the joint probability of the 3D localization and the WISE W1 luminosity (an observable proxy for stellar mass). For the full or top 20 list of galaxies in the 90% volume go either to the NED Gravitational Wave Followup service at https://ned.ipac.caltech.edu/uri/NED::GWF/ or click on the following links: Full List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S251112cm/4 Top 20 List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S251112cm/4/20 The NED-GWF service provides downloadable galaxy lists and visualizations for candidate host galaxies. For each GW alert, these products are automatically generated and made available within minutes to expedite efficient electromagnetic follow-up observations. The NED top 20 list is sorted by the joint probability of the 3D localization and the WISE W1 luminosity, but users can sort on additional pre-computed prioritization metrics (star formation rate, P_3D * P_SFR; and specific star formation rate, P_3D * P_sSFR; etc.) which are available via downloading the entire galaxy list inside the event's probability volume. | objname| ra| dec|objtype| DistMpc|DistMpc_unc| m_NUV| m_NUV_unc| m_Ks| m_Ks_unc| m_W1| m_W1_unc| P_3D|P_3D_LumW1| |-------------------------|--------------|--------------|-------|-----------|-----------|------------|------------|------------|------------|------------|------------|--------|----------| | IC 1633| 17.48145| -45.93116| G| 96.06| 3.43| null| null| 8.396| 0.025| 8.999| 0.006|8.02e-06| 1.10e-08| | IC 0564| 146.58792| 3.07130| G| 75.75| 2.62| null| null| 10.033| 0.035| 10.010| 0.006|2.41e-05| 8.10e-09| | IC 1464B| 345.79587| -8.98909| G| 105.88| 0.59| null| null| 10.015| 0.036| 9.741| 0.006|8.31e-06| 6.98e-09| |WISEA J100012.04+093856.0| 150.05020| 9.64890| G| 78.82| 0.30| null| null| 11.073| 0.096| 10.233| 0.006|2.04e-05| 6.04e-09| | UGC 05226| 146.51479| 4.40348| G| 66.86| 15.78| 18.763| 0.092| 10.211| 0.041| 10.083| 0.089|2.21e-05| 5.42e-09| | ESO 197- G 021| 31.13585| -52.17213| G| 87.54| 0.39| null| null| 9.099| 0.026| 9.375| 0.006|6.49e-06| 5.21e-09| | MCG -01-24-010| 140.09147| -7.88074| G| 53.94| 2.54| 15.885| 0.007| 10.054| 0.032| 9.821| 0.030|2.49e-05| 5.05e-09| | MRK 0421| 166.11381| 38.20883| G| 85.15| 33.84| null| null| 9.996| 0.029| 9.258| 0.005|5.81e-06| 4.92e-09| | IC 1464A| 345.80030| -8.99285| G| 107.09| 0.04| null| null| 11.963| 0.011| 10.070| 0.006|7.57e-06| 4.81e-09| | NGC 7364| 341.10153| -0.16213| G| 76.48| 8.25| 16.366| 0.001| 9.478| 0.028| 9.218| 0.003|6.74e-06| 4.80e-09| | IC 1471| 347.18676| -12.63948| G| 83.00| 17.58| 17.246| 0.027| 10.334| 0.035| 10.290| 0.006|1.49e-05| 4.63e-09| | ESO 243- G 051| 17.83050| -45.93204| G| 94.78| 0.36| 17.032| 0.008| 10.015| 0.031| 10.036| 0.006|8.85e-06| 4.53e-09| | NGC 2951 NED01| 144.92019| -0.23515| G| 70.23| 0.53| 18.380| 0.003| 10.498| 0.057| 10.537| 0.004|2.33e-05| 4.19e-09| | IC 2471| 141.30071| -6.82994| G| 58.50| 12.39| 18.644| 0.054| 9.949| 0.034| 10.076| 0.006|2.19e-05| 4.12e-09| | NGC 3070| 149.52893| 10.35980| G| 60.25| 5.89| 18.225| 0.068| 9.260| 0.030| 9.503| 0.006|1.21e-05| 4.12e-09| | ESO 197- G 018| 30.62846| -50.93160| G| 110.00| 24.82| null| null| 9.612| 0.028| 9.779| 0.006|4.35e-06| 3.80e-09| | NGC 2951 NED02| 144.91664| -0.23524| G| 71.31| 0.04| 18.383| 0.003| 12.873| 0.052| 10.592| 0.004|2.13e-05| 3.75e-09| | ESO 243- G 045| 17.26888| -45.77349| G| 82.00| 9.44| 18.245| 0.024| 9.713| 0.035| 9.964| 0.006|9.07e-06| 3.71e-09| | IC 0563| 146.58473| 3.04574| G| 57.00| 22.05| 16.948| 0.010| 10.810| 0.054| 10.328| 0.027|2.54e-05| 3.62e-09| | ESO 197- G 010| 28.30237| -49.56039| G| 76.43| 6.54| null| null| 8.882| 0.034| 9.458| 0.006|6.17e-06| 3.50e-09| Table 1: Top 20 galaxies in NED-LVS that fall in the 90% probability volume for S251112cm sorted by the joint probability of 3D position and WISE W1 luminosity (P_3D * P_LumW1). Galaxy is the NED preferred name. RA and Dec are the Equatorial coordinates in degrees (J2000). Objtype is the object type of the galaxy candidate. Distance is the distance to the galaxy in Mpc. m_NUV and mErr_NUV are the apparent magnitude and error from GALEX. m_Ks and mErr_Ks are the apparent magnitude and error from 2MASS. m_W1 and mErr_W1 are the apparent magnitude and error from AllWISE. P_3D is the probability that the galaxy is in the volume given the distance of GW event. P_3D_LumW1 is the joint probability within the volume weighted by the WISE1 luminosity of the galaxy (P_3D * P_LumW1). View this GCN Circular online at https://gcn.nasa.gov/circulars/42693. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40756] GRB 251115A: Fermi GBM Final Real-time Localization
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42692 SUBJECT: GRB 251115A: Fermi GBM Final Real-time Localization DATE: 25/11/15 03:30:39 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 03:20:02 UT on 15 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251115A (trigger 784869607.66655 / 251115139). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 334.5, Dec = -4.5 (J2000 degrees, equivalent to J2000 22h 18m, -4d 30'), with a statistical uncertainty of 4.1 degrees. The angle from the Fermi LAT boresight is 80.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251115139/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251115139/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251115139/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42692. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40755] LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42691 SUBJECT: LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates DATE: 25/11/15 03:16:35 GMT FROM: Xander J Hall at Carnegie Mellon University <xjh(a)andrew.cmu.edu> Xander J. Hall (CMU), Tomás Cabrera (CMU), Julius Gassert (CMU/LMU), Lei Hu (UPenn), Antonella Palmese (CMU), Brendan O’Connor (CMU), Igor Andreoni (UNC), on behalf of the Gravitational Wave MultiMessenger Astronomy DECam Survey (GW-MMADS) team report: We observed the high probability area of the LVK gravitational wave candidate S251112cm (GCN 42650) using the wide-field Dark Energy Camera (DECam) on the 4m Blanco telescope. Observations started at 2025-11-14 00:03 UTC (Prop ID: 2023B-851374; PI Palmese & Andreoni) and focused on the southern lobe of the Bilby skymap (GCN 42690; 30% of the total posterior probability). We run the SFFT difference imaging (Hu et al. 2022) on the available images, filter out likely stars and moving objects, and then visually inspect the remaining transients. We report on TNS 54 new transients within the observed area, and we report here select transients: | id | AT name | ra | dec | discovery_date (UT) | mag_g | mag_g_err | mag_g-mag_i | NED separation | | ------------------------ | ---------- | ---------- | ---------- | ----------------------- | ------ | ----- | ----- | ----- | | T202511140018095m335115* | AT 2025adjp | 4.539622 | -33.854284 | 2025-11-14 02:08:26.016 | 21.13 | 0.04 | 0.25 | 92.7", 94.5", 94.6" | T202511140030086m410443 | AT 2025adkl | 7.535766 | -41.078709 | 2025-11-14 02:13:43.104 | 20.91 | 0.03 | -0.14 | 90.5" *This transient is within 2' of three NED in-volume galaxies. We note while both of these transients are within 2' of a NED in-volume galaxy (GCN 42653), they are both near galaxies with LS DR9 photo-z > 0.12 which would place them outside of the volume. Further analysis is underway. We thank the CTIO and NOIRLab staff for supporting these observations and the data calibration. View this GCN Circular online at https://gcn.nasa.gov/circulars/42691. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40754] LIGO/Virgo/KAGRA S251112cm: Updated Sky localization and false alarm rate estimate
by GCN Circulars 15 Nov '25

15 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42690 SUBJECT: LIGO/Virgo/KAGRA S251112cm: Updated Sky localization and false alarm rate estimate DATE: 25/11/15 00:41:29 GMT FROM: Colm Talbot at Princeton University <talbotcolm(a)gmail.com> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S251112cm (GCN Circular 42650). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,1, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S251112cm For the Bilby.multiorder.fits,1 sky map, the 90% credible region is 1681 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 93 +/- 27 Mpc (a posteriori mean +/- standard deviation). The false alarm rate, as estimated by the MBTA SSM analysis pipeline with an updated background model, has been updated to about one in 4 years. The online search for sub-solar-mass regions is covered by two independent pipelines: MBTA SSM and GstLAL SSM [2]. For the parameter space relevant to the present candidate, only MBTA SSM provides online coverage; therefore, the candidate was triggered solely by MBTA SSM. For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 [2] https://emfollow.docs.ligo.org/userguide/analysis/index.html#false-alarm-ra… View this GCN Circular online at https://gcn.nasa.gov/circulars/42690. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40753] GRB 251113A: Glowbug gamma-ray detection
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42689 SUBJECT: GRB 251113A: Glowbug gamma-ray detection DATE: 25/11/14 22:40:15 GMT FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung(a)nrl.navy.mil> C.C. Cheung, R. Woolf, M. Kerr, J.E. Grove (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge, D. Kocevski (MSFC), and M.S. Briggs (UAH) report: The Glowbug gamma-ray telescope [1,2,3], operating on the International Space Station, reports the detection of GRB 251113A, which was also detected by Fermi/GBM (GCN 42671, 42672) and AstroSat/CZTI (GCN 42688). Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2025-11-13 17:37:28.512 with a duration of 24.6 s and a total significance of about 82 sigma. The light curve comprises three primary peaks at ~T0+8s, +12s, and +18s. Low-level emission may be present up to ~T0+37s. Note that data from ~T0+22s to T0+26s suffered from deadtime in various detectors. The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS. Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Program’s STP-H9 to the ISS and operated until 2024 April when it was put in safe storage on orbit. Glowbug was removed from storage and resumed operation on 2025 September 12. [1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959 [2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O [3] Woolf, R.S. et al. 2024, Proc. SPIE, 13151, id. 1315108 Distribution Statement A: Approved for public release. Distribution is unlimited. View this GCN Circular online at https://gcn.nasa.gov/circulars/42689. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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