November 2025 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[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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