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

[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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