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

15 Nov '25

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

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

15 Nov '25

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

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

15 Nov '25

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

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

14 Nov '25

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

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[vsnet-grb-info 40752] GRB 251113A: AstroSat CZTI detection
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42688 SUBJECT: GRB 251113A: AstroSat CZTI detection DATE: 25/11/14 21:27:07 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> A. Goyal (IITB), A. Arya (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 long GRB 251113A which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 42671). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-11-13 17:37:42.84 UTC. The measured peak count rate associated with the burst is 208 (+40, -21) counts/s above the background in the combined data of all quadrants, with a total of 2657 (+431, -393) counts. The local mean background count rate was 269 (+4, -5) counts/s. Using cumulative rates, we measure a T90 of 23 (+2, -5) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-11-13 17:37:42.35 UTC. The measured peak count rate associated with the burst is 350 (+68, -53) counts/s above the background in the combined data of all quadrants, with a total of 4325 (+900, -914) counts. The local mean background count rate was 1169 (+11, -11) counts/s. We measure a T90 of 22 (+2, -4) s from the cumulative Veto light curve. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/42688. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40751] GRB 251114B: Fermi GBM Final Real-time Localization
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42687 SUBJECT: GRB 251114B: Fermi GBM Final Real-time Localization DATE: 25/11/14 20:49:04 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 20:38:30 UT on 14 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251114B (trigger 784845515.202048 / 251114860). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 160.1, Dec = -85.2 (J2000 degrees, equivalent to J2000 10h 40m, -85d 12'), with a statistical uncertainty of 3.5 degrees. The angle from the Fermi LAT boresight is 57.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251114860/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251114860/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251114860/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42687. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40750] GRB 251112A: Swift-BAT refined analysis
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42686 SUBJECT: GRB 251112A: Swift-BAT refined analysis DATE: 25/11/14 20:37:19 GMT FROM: Rahul Gupta at NASA GSFC <rahul.gupta(a)nasa.gov> D. Sadaula (GSFC/UMBC), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), A. Mei (INAF-OAB) M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 251112A (trigger #1413695) (Mei, et al., GCN Circ. 42656). The BAT ground-calculated position is RA, Dec = 274.081, 24.158 deg which is RA(J2000) = 18h 16m 19.5s Dec(J2000) = +24d 09' 28.8" with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted BAT light curve shows multi-peaked emission starting ~T-28 sec. T90 (15-350 keV) is 55.42 +- 6.65 sec (estimated error including systematics). The time-averaged spectrum from T-28.30 to T+32.38 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.77 +- 0.75, and Epeak of 48.4 +- 11.9 keV (chi squared 86.37 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 7.6 +- 0.9 x 10^-07 erg/cm2 and the 1-sec peak flux measured from T+1.05 sec in the 15-150 keV band is 0.7 +- 0.1 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.86 +- 0.15 (chi squared 94.39 for 57 d.o.f.). All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1413695 View this GCN Circular online at https://gcn.nasa.gov/circulars/42686. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40749] Konus-Wind detection of GRB 251108C
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42685 SUBJECT: Konus-Wind detection of GRB 251108C DATE: 25/11/14 20:07:42 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru> A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The long-duration GRB 251108C (AstroSat-CZTI detection: Salunke et al., GCN 42664; IPN triangulation: Kozyrev et al., GCN 42680) triggered Konus-Wind at T0=83283.415 s UT (23:08:03.415). The burst light curve shows a multipeaked structure which starts at ~T0-0.2 s and has a total duration of ~8.5 s. The emission is seen up to ~6 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB251108_T83283/ As observed by Konus-Wind, the burst had a fluence of 1.51(-0.19,+0.23)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0-0.172 s, of 1.23(-0.23,+0.26)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.05(-0.10,+0.11) and Ep = 1415(-316,+464) keV (chi2 = 55/69 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -1.7 (chi2 = 53/68 dof). The spectrum near the maximum count rate (measured from T0 to T0+0.256 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model with alpha = -0.96(-0.17,+0.22) and Ep = 2202(-834,+1554) keV (chi2 = 26/30 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -1.4 (chi2 = 26/29 dof). All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/42685. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40748] Fermi trigger No 784717756: Global MASTER-Net observations report
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42684 SUBJECT: Fermi trigger No 784717756: Global MASTER-Net observations report DATE: 25/11/14 18:31:18 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB251113.38 (trigger No 784717756,18h 51m 24.00s , +17d 07m 58.8s, R=28.6) errorbox 58396 sec after notice time and 58428 sec after trigger time at 2025-11-14 01:22:59 UT, with upper limit up to 20.0 mag. The observations began at zenith distance = 64 deg. The sun altitude is -25.2 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB251113.38 errorbox 1 days 30851 sec after notice time and 1 days 30882 sec after trigger time at 2025-11-14 17:43:53 UT, with upper limit up to 16.8 mag. The observations began at zenith distance = 75 deg. The sun altitude is -42.9 deg. The galactic latitude b = 7 deg., longitude l = 49 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3041181 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 58488 | 2025-11-14 01:22:59 | MASTER-OAFA | (20h 52m 07.43s , +09d 10m 19.0s) | C | 120 | 19.9 | 58624 | 2025-11-14 01:25:05 | MASTER-OAFA | (20h 52m 07.40s , +09d 10m 19.6s) | C | 140 | 20.0 | 58787 | 2025-11-14 01:27:33 | MASTER-OAFA | (20h 52m 07.36s , +09d 10m 20.0s) | C | 170 | 20.0 | 58908 | 2025-11-14 01:30:29 | MASTER-OAFA | (20h 52m 07.34s , +09d 10m 20.1s) | C | 60 | 19.6 | 58974 | 2025-11-14 01:31:35 | MASTER-OAFA | (20h 52m 07.33s , +09d 10m 20.0s) | C | 60 | 19.6 | 59040 | 2025-11-14 01:32:41 | MASTER-OAFA | (20h 52m 07.32s , +09d 10m 20.4s) | C | 60 | 19.5 | 117313 | 2025-11-14 17:43:53 | MASTER-Kislovodsk | (19h 11m 01.28s , +05d 00m 12.1s) | C | 60 | 15.4 | 117313 | 2025-11-14 17:43:53 | MASTER-Kislovodsk | (19h 11m 07.05s , +05d 22m 44.2s) | C | 60 | 15.7 | 117453 | 2025-11-14 17:45:13 | MASTER-Kislovodsk | (18h 14m 55.94s , +24d 10m 07.2s) | C | 180 | 16.4 | 117453 | 2025-11-14 17:45:13 | MASTER-Kislovodsk | (18h 15m 01.21s , +24d 32m 41.2s) | C | 180 | 16.8 | 117653 | 2025-11-14 17:48:33 | MASTER-Kislovodsk | (18h 34m 43.18s , +18d 08m 20.3s) | C | 180 | 16.1 | 117653 | 2025-11-14 17:48:33 | MASTER-Kislovodsk | (18h 34m 49.05s , +18d 30m 54.3s) | C | 180 | 16.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/42684. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40747] Konus-Wind detection of GRB 251103A
by GCN Circulars 14 Nov '25

14 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42683 SUBJECT: Konus-Wind detection of GRB 251103A DATE: 25/11/14 16:45:00 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 251103A (SVOM-ECLAIRs detection: Hu et al., GCN 42534; Fermi-GBM detection: The Fermi GBM team, GCN 42536; Sonawane and Godwin, GCN 42553; SVOM-GRM detection: Wang et al., GCN 42552; Insight-HXMT/HE detection: Ren et al., GCN 42572) triggered Konus-Wind at T0=17189.335 s UT (04:46:29.335). The burst light curve shows a single pulse which starts at ~T0-0.5 s and has a total duration of ~5.5 s. The emission is seen up to ~2 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB251103_T17189/ As observed by Konus-Wind, the burst had the total fluence of 9.48(-0.93,+1.02)x10^-6 erg/cm2, and the 64-ms peak flux, measured from T0+0.022 s, of 6.52(-2.04,+2.79)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.33(-0.71,+1.08), the high energy photon index beta = -2.21(-0.11,+0.09), the peak energy Ep = 86(-15,+25) keV (chi2 = 86/80 dof). The spectrum near the maximum count rate (measured from T0 to T0+0.256 s) is best fit in the 20 keV - 2 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.97(-0.42,+0.99), the high energy photon index beta = -2.25(-7.75,+0.39), the peak energy Ep = 292(-160,+184) keV (chi2 = 16/18 dof). Assuming the redshift z=0.76 (Izzo et al., GCN 42540) and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the following rest-frame parameters: the isotropic energy release E_iso is 1.53(-0.15,+0.16)x10^52 erg, the peak luminosity L_iso is 1.85(-0.58,+0.79)x10^52 erg/s, the rest-frame peak energy of the time-averaged spectrum Ep,i,z is 151(-27,+44) keV and the spectrum near the maximum count rate Ep,p,z is 513(-281,+324) keV. With the obtained estimates, GRB 251103A is inside 68% prediction bands for both the 'Amati' and the 'Yonetoku' relations derived for the sample of >300 long KW GRBs with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021), see http://www.ioffe.ru/LEA/GRBs/GRB251103_T17189/GRB251103A_rest_frame.pdf All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/42683. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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