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

[vsnet-grb-info 40952] GRB 251129A: Correction to the position of the optical counterpar
by GCN Circulars 29 Nov '25

29 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42883 SUBJECT: GRB 251129A: Correction to the position of the optical counterpar DATE: 25/11/29 04:48:59 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Alan Watson (UNAM) reports: The position of the optical counterpart given by Angulo et al. (GCN 42880) was not given completely correctly. The position was given correctly in sexagesimal but not in degrees. The correct position is: RA(J2000) = 14:57:18.88 = 224.3286 degrees Dec(J2000) = +79:17:34.8 = 79.2930 degrees We apologize for this error. We thank Huali Li for bringing this mistake to our attention. View this GCN Circular online at https://gcn.nasa.gov/circulars/42883. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40951] GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
by GCN Circulars 29 Nov '25

29 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42882 SUBJECT: GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data DATE: 25/11/29 04:12:26 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> C. Wu, H. L. Li, L.P. Xin, Y. L. Qiu (NAOC), J. T. Palmerio (CEA), W. J. Tan (IHEP), D. F. Kong (GXU) report on behalf of the SVOM team. After the trigger by SVOM/ECLAIRs at 2025-11-29T02:32:05 UTC (T0), SVOM/VT performed an automatic slew to the burst GRB 251129A (sb25112901, Tan et al., GCN 42879). The observation began at 2025-11-29T02:43:03, 658 seconds after T0, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. The optical counterpart reported (Angulo et al., GCN 42880) was clearly detected in the 1-bit subimages and source lists downloaded via VHF network in both channels. The magnitudes are : Mid_time Band Magnitude (AB) 808 sec VT_B 18.63+/-0.01 mag 808 sec VT_R 18.02+/-0.01 mag Our photometry was derived in AB magnitude and not corrected for Galactic extinction. Given the VT color, it is likely a low redshift GRB. 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. SVOM/VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS. View this GCN Circular online at https://gcn.nasa.gov/circulars/42882. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40950] GRB 251128A: Fermi GBM Observation
by GCN Circulars 29 Nov '25

29 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42881 SUBJECT: GRB 251128A: Fermi GBM Observation DATE: 25/11/29 03:48:05 GMT FROM: rhamburg(a)usra.edu R. Hamburg (USRA), M. Godwin (UAH), Padraig McDermott (UCD), and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 04:22:21.61 UT on 28 November 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251128A (trigger 785996546/251128182; GCN 42865), which was also detected by Swift/BAT-GUANO (DeLaunay et al. 2025, GCN 42874). The angle from the Fermi LAT boresight is 114 degrees. The GBM light curve consists of multiple peaks with a duration (T90) of about 47 s (50-300 keV). The time-averaged spectrum from T0-0.0 to T0+44 s is best fit by a Band function with Epeak = 124 +/- 2, alpha = -0.92 +/- 0.01, and beta = -2.0 +/- 0.03. The event fluence (10-1000 keV) in this time interval is (1.95 +/- 0.13)e-05 ergs/cm^2. The 1-sec peak photon flux measured starting from T0+9.1 s in the 10-1000 keV band is 11.8 +/- 0.5 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/42881. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40949] GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
by GCN Circulars 29 Nov '25

29 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42880 SUBJECT: GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate DATE: 25/11/29 03:38:10 GMT FROM: Camila Angulo Valdez at UNAM <camiangulo(a)astro.unam.mx> Camila Angulo (UNAM), Nikos Mandarakas (LAM), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), N. A. Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), Antonio de Ugarte Postigo (LAM), Wenjun Tan (IHEP), Defeng Kong (GXU), Wenjin Xie (NAOC), Donghua Zhao (NAOC), Hatsune Goto (Kanazawa Univ.) report: We imaged the field of the SVOM GRB 251129A (Tan et al., GCN Circ. 42877) using the DDRAGO two-channel wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2025-11-29 02:51:22 to 02:57:11 UTC (from 20.0 to 25.8 minutes after the trigger) and obtained 5 minutes of simultaneous exposure in the r and z filters. The data were reduced, coadded, and analyzed with the ASU pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. We detect an uncatalogued source just outside the MXT error circle at: RA(J2000) = 14:57:18.88 = 224.2949 degrees Dec(J2000) = +79:17:34.8= 79.3050 degrees with an uncertainty of 0.5 arcsec. The preliminary magnitude derived for that source is: r = 18.30 +/- 0.01 z = 18.03 +/- 0.01 Further observations are ongoing. We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/42880. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40948] GRB 251129A: SVOM detection of a burst
by GCN Circulars 29 Nov '25

29 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42879 SUBJECT: GRB 251129A: SVOM detection of a burst DATE: 25/11/29 03:15:27 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Wenjun Tan (IHEP), Defeng Kong (GXU), Wenjin Xie, Donghua Zhao (NAOC), Hatsune Goto (Kanazawa Univ.) report on behalf of the SVOM mission team: At 2025-11-29T02:32:05 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251129A (SVOM burst-id sb25112901). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was only detected by the Image Trigger (IMT), which produced a sequence of 5 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 8.82 in the [8-50] keV energy band over a time window of 81.92 seconds starting at 2025-11-29T02:31:24. The localization of the best alert is R.A., Dec. 224.5380, 79.4287 degrees (J2000) with a 90% confidence level (C.L.) radius of 8.96 arcmin (including systematic error of 2 arcmin added in quadrature). SVOM slewed to the burst. SVOM/MXT began observing the field at 2025-11-29T02:45:53 UTC, 828 seconds after T0. Using onboard processed data we found an uncatalogued X-ray source located at R.A., Dec. 224.3258, 79.3004 degrees: R.A. (J2000) = 14h57m01.94s Dec. (J2000) = 79d18m32.94s with a 90% C.L. radius of 25.08 arcseconds. This location is 7.82 arcminutes from the ECLAIRs onboard position. This position may be improved as more data is received. VT began observing the field after the slew. The analysis of the data will be published in a future circular. 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. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Wenjun Tan: tanwj(a)ihep.ac.cn Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42879. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40947] SVOM GRB251129.11: Global MASTER-Net observations report
by GCN Circulars 29 Nov '25

29 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42878 SUBJECT: SVOM GRB251129.11: Global MASTER-Net observations report DATE: 25/11/29 03:14:31 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) was pointed to the SVOM GRB251129.11 (trigger No 1764383485,14h 58m 09.12s , +79d 25m 43.3s, R=0.1493) errorbox 9 sec after notice time and 997 sec after trigger time at 2025-11-29 02:48:01 UT, with upper limit up to 18.9 mag. Observations started at twilight. The observations began at zenith distance = 45 deg. The sun altitude is -16.3 deg. The galactic latitude b = 36 deg., longitude l = 116 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3054567 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 1057 | 2025-11-29 02:48:01 | MASTER-Kislovodsk | (14h 59m 33.58s , +79d 37m 30.3s) | C | 120 | 18.3 | 1177 | 2025-11-29 02:48:01 | MASTER-Kislovodsk | (14h 59m 33.58s , +79d 37m 30.3s) | C | 360 | 18.9 | Coadd 1057 | 2025-11-29 02:48:01 | MASTER-Kislovodsk | (15h 21m 37.07s , +79d 09m 16.3s) | C | 120 | 18.4 | 1197 | 2025-11-29 02:50:21 | MASTER-Kislovodsk | (14h 59m 33.13s , +79d 37m 36.2s) | C | 120 | 18.0 | 1197 | 2025-11-29 02:50:21 | MASTER-Kislovodsk | (15h 21m 37.81s , +79d 09m 22.5s) | C | 120 | 18.2 | 1337 | 2025-11-29 02:52:41 | MASTER-Kislovodsk | (14h 59m 32.62s , +79d 37m 42.8s) | C | 120 | 18.0 | 1337 | 2025-11-29 02:52:41 | MASTER-Kislovodsk | (15h 21m 38.00s , +79d 09m 30.4s) | C | 120 | 18.0 | 1487 | 2025-11-29 02:55:11 | MASTER-Kislovodsk | (14h 59m 32.17s , +79d 37m 50.0s) | C | 120 | 17.8 | 1607 | 2025-11-29 02:55:11 | MASTER-Kislovodsk | (14h 59m 32.18s , +79d 37m 50.0s) | C | 360 | 18.3 | Coadd 1487 | 2025-11-29 02:55:11 | MASTER-Kislovodsk | (15h 21m 37.94s , +79d 09m 39.5s) | C | 120 | 18.0 | 1627 | 2025-11-29 02:57:31 | MASTER-Kislovodsk | (14h 59m 31.42s , +79d 37m 57.4s) | C | 120 | 17.6 | 1627 | 2025-11-29 02:57:31 | MASTER-Kislovodsk | (15h 21m 37.84s , +79d 09m 49.2s) | C | 120 | 17.7 | 1766 | 2025-11-29 02:59:50 | MASTER-Kislovodsk | (14h 59m 30.65s , +79d 38m 04.2s) | C | 120 | 17.5 | 1766 | 2025-11-29 02:59:50 | MASTER-Kislovodsk | (15h 21m 37.58s , +79d 09m 57.9s) | C | 120 | 17.8 | 1906 | 2025-11-29 03:02:10 | MASTER-Kislovodsk | (14h 59m 29.69s , +79d 38m 11.3s) | C | 120 | 17.6 | 1906 | 2025-11-29 03:02:10 | MASTER-Kislovodsk | (15h 21m 37.28s , +79d 10m 06.9s) | C | 120 | 17.9 | 2046 | 2025-11-29 03:04:31 | MASTER-Kislovodsk | (14h 59m 28.84s , +79d 38m 19.5s) | C | 120 | 17.7 | 2046 | 2025-11-29 03:04:31 | MASTER-Kislovodsk | (15h 21m 37.01s , +79d 10m 17.3s) | C | 120 | 17.9 | 2186 | 2025-11-29 03:06:50 | MASTER-Kislovodsk | (14h 59m 27.87s , +79d 38m 27.5s) | C | 120 | 17.7 | 2186 | 2025-11-29 03:06:50 | MASTER-Kislovodsk | (15h 21m 36.63s , +79d 10m 27.4s) | C | 120 | 17.9 | 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/42878. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40946] GRB 251129A: SVOM detection of a burst
by GCN Circulars 29 Nov '25

29 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42877 SUBJECT: GRB 251129A: SVOM detection of a burst DATE: 25/11/29 03:14:08 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Wenjun Tan (IHEP), Defeng Kong (GXU), Wenjin Xie, Donghua Zhao (NAOC), Hatsune Goto (Kanazawa univ.) report on behalf of the SVOM mission team: At 2025-11-29T02:32:05 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251129A (SVOM burst-id sb25112901). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was only detected by the Image Trigger (IMT), which produced a sequence of 5 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 8.82 in the [8-50] keV energy band over a time window of 81.92 seconds starting at 2025-11-29T02:31:24. The localization of the best alert is R.A., Dec. 224.5380, 79.4287 degrees (J2000) with a 90% confidence level (C.L.) radius of 8.96 arcmin (including systematic error of 2 arcmin added in quadrature). SVOM slewed to the burst. SVOM/MXT began observing the field at 2025-11-29T02:45:53 UTC, 828 seconds after T0. Using onboard processed data we found an uncatalogued X-ray source located at R.A., Dec. 224.3258, 79.3004 degrees: R.A. (J2000) = 14h57m01.94s Dec. (J2000) = 79d18m32.94s with a 90% C.L. radius of 25.08 arcseconds. This location is 7.82 arcminutes from the ECLAIRs onboard position. This position may be improved as more data is received. VT began observing the field after the slew. The analysis of the data will be published in a future circular. 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. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Wenjun Tan: tanwj(a)ihep.ac.cn Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/42877. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40945] GRB 251126A: Swift-BAT refined analysis
by GCN Circulars 29 Nov '25

29 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42876 SUBJECT: GRB 251126A: Swift-BAT refined analysis DATE: 25/11/29 01:05:23 GMT FROM: Amy <yarleen(a)gmail.com> S. D. Barthelmy (GSFC), R. Caputo (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 251126A (trigger #1417793) (Caputo et al., GCN Circ. 42843). The BAT ground-calculated position is RA, Dec = 99.939, 54.989 deg which is RA(J2000) = 06h 39m 45.4s Dec(J2000) = +54d 59' 21.9" with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 96%. The mask-weighted light curve shows two overlapping pulses. The first pulse peaks at ~T+1 s, and the second pulse peaks at ~T+4 s. The overall structure starts at ~T0 and ends at ~T+10 s. T90 (15-350 keV) is 9.00 +- 2.00 sec (estimated error including systematics). The time-averaged spectrum from T-0.41 to T+10.59 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.43 +- 0.71, and Epeak of 51.4 +- 8.8 keV (chi squared 58.43 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 4.4 +- 0.4 x 10^-07 erg/cm2 and the 1-sec peak flux measured from T+0.59 sec in the 15-150 keV band is 1.3 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.76 +- 0.12 (chi squared 72.99 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/1417793 View this GCN Circular online at https://gcn.nasa.gov/circulars/42876. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40944] GRB 251126A: TShAO, Mondy, and AbAO optical observations
by GCN Circulars 28 Nov '25

28 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42875 SUBJECT: GRB 251126A: TShAO, Mondy, and AbAO optical observations DATE: 25/11/28 21:30:36 GMT FROM: Alina Volnova at IKI RAS <alinusss(a)gmail.com> N. S. Pankov (HSE, IKI), A. A. Volnova (IKI), I. V. Reva (FAI), E. Klunko (ISTP), R. Ya. Inasaridze (AbAO), A. S. Moskvitin (SAO RAS), A. S. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We observed the field of Swift GRB 251126A (Caputo et al., GCN 42843; Evans, GCN 42845; Goad et al., GCN 42851) with the Zeiss-1000 1m telescope of the Tien-Shan Observatory (TSHAO), the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy), and the AS-32 0.7m telescope of Abastumani Observatory (AbAO) taking several frames in R-band. The observations began at TSHAO on 2025-11-27 at 16:32 UT (~0.907 days after the trigger), further observations at AZT-33IK started at 18:55 (~1.01 days after the trigger), then followed by AbAO starting at 20:09 UT (~1.06 days after the trigger). The optical afterglow (Swain, GCN 42844; Fu et al., GCN 42848; Reguitti et al., GCN 42849; Broens et al., GCN 42850; Anguloet al., GCN 42855; Pulido-Torres et al; GCN 42856; Gupta et al., GCN 42857; Cotter et al., GCN 42858; Seki et al, GCN 42859; Volnova et al, GCN 42861; Breeveld, GCN 42863; Gupta et al., GCN 42864; Burkhonov et al., GCN 42866; Maksut et al., GCN 42868; Moskvitin et al., GCN 42870; Adami et al., GCN 42871) is not detected in the stacked frames from Zeiss-1000 and AS-32 and is seen in the stacked AZT-33IK frame. The preliminary results and observational details are provided below. Date UT start t-T0 Exp. Filter OT Err. UL Site/Instrum (mid,days) (n*s) (3sigma) 2025-11-27 16:32:42 0.90745 35*90 R n/d n/d 21.2 TSHAO/Zeiss-1000 2025-11-27 18:55:21 1.01164 30*120 R 22.10 0.12 22.3 Mondy/AZT-33IK 2025-11-27 20:09:59 1.06624 72*60 R n/d n/d 21.9 AbAO/AS-32 The photometry is based on several nearby stars from the USNO-B1 catalogue (R2 magnitudes) and is not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/42875. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40943] GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
by GCN Circulars 28 Nov '25

28 Nov '25

TITLE: GCN CIRCULAR NUMBER: 42874 SUBJECT: GRB 251128A: Swift/BAT-GUANO localization skymap of a burst DATE: 25/11/28 21:14:53 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 251128A onboard (T0: 2025-11-28T04:22:21.61 UTC, Fermi Trig 785996546) 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 21.2 in a 4.096 s analysis time bin, starting at T0 - 1.024 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 550 deg2 and the 50% credible area is 74 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 42865). The combined Fermi/GBM+NITRATES 90% credible area is 49 deg2 and the 50% credible area is 14 deg2. A plot of the probability skymap can be viewed here: [skymap_plot](https://guano.swift.psu.edu/trigger_report?id=785996578/#:~:te… The probability skymap and joint skymap files can be downloaded from the links here [skymap_fits_file](https://guano.swift.psu.edu/files/785996578/0_n_PROBMAP) [joint_skymap_fits_file](https://guano.swift.psu.edu/files/785996578/0_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=785996578 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/42874. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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