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

[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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