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

[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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