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GRB 251128A

GCN Circular 42898

Subject

GRB 251128A: AstroSat CZTI detection

Date

2025-11-29T18:47:43Z (12 hours ago)

From

Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com>

Via

Web form

M. Tembhurnikar (IUCAA), A. Arya (IITB), A. Goyal (IITB), S. Salunke (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 251128A which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 42865Loading...
 
 ), Swift BAT-GUANO (DeLaunay et. al., GCN Circ. 42874Loading...
 
 ), and Insight-HXMT/HE (Zhang et. al., GCN Circ. 42893Loading...
 
 ).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2025-11-28 04:23:02 UTC. The measured peak count rate associated with the burst is 154 (+2, -2) counts/s above the background in the combined data of two quadrants (out of four), with a total of 2558 (+298, -336) counts. The local mean background count rate was 260 (+2, -2) counts/s. Using cumulative rates, we measure a T90 of 45.3 (+2.8, -2.2) s.

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2025-11-28 04:23:52 UTC. The measured peak count rate associated with the burst is 509 (+72, -62) counts/s above the background in the combined data of all quadrants, with a total of 5062 (+723, -752) counts. The local mean background count rate was 1445 (+6, -5) counts/s. We measure a T90 of 47.1 (+1.9, -2.7) 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

GCN Circular 42895

Subject

GRB 251128A: GECAM-B detection

Date

2025-11-29T15:11:17Z (16 hours ago)

From

zhangjinpeng@ihep.ac.cn

Via

Web form

Jin-Peng Zhang, Jia-Cong Liu, Chen-Wei Wang, Chao Zheng, Shao-Lin Xiong (IHEP) report on behalf of GECAM team:

GECAM-B was triggered in-flight by a long burst, GRB 251128A, at 2025-11-28T04:22:22.950 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #42865Loading...
 
 ).

According to the GECAM-B light curves in about 40-6000 keV, this burst mainly consists of multiple pulses with a duration (T90) of 46 +2/-4 s.

The GECAM-B light curve can be found here:
https://www.bursthub.cn//admin/static/gecambgrb251128A.png

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).

GCN Circular 42894

Subject

GRB 251128A: SVOM/GRM observation of a long burst

Date

2025-11-29T14:47:25Z (16 hours ago)

From

zhangjinpeng@ihep.ac.cn

Via

Web form

SVOM/GRM team: Jin-Peng Zhang, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)

SVOM/ECLAIRs team: Jean-Luc Atteia (IRAP)

Report on behalf of the SVOM team:

SVOM/GRM on-ground search was triggered by GRB 251128A at 2025-11-28T04:22:24.000 (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN #42865Loading...
 
 ).

The GRM light curve shows that this burst consists of multiple pulses with a T90 of 47 +8/-5 s in the 15-5000 keV band.

The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb251128A.png

In addition, the position of this burst, as determined by Fermi/GBM (RA=117.5, Dec = 52.2, GCN #42865Loading...
 
 ), is located at about 139.4 degrees from the SVOM optical axis, which is out of the ECLAIRs field of view.

With this localization, the time-averaged spectrum from T0-10 to T0+45 s is best fit by a power law function. The power law index is -2.36 +0.22/-0.28. The event fluence (10-1000 keV) in this time interval is (3.08 +0.34/-0.35)E-05 erg/cm^2.

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: Jin-Peng Zhang (IHEP) (zhangjinpeng@ihep.ac.cn)

GCN Circular 42893

Subject

GRB 251128A: Insight-HXMT/HE detection

Date

2025-11-29T14:43:15Z (16 hours ago)

From

zhangjinpeng@ihep.ac.cn

Via

Web form

Jin-Peng Zhang, Chen-Wei Wang, Chao Zheng, and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team:

At 2025-11-28T04:22:22.000 (T0), Insight-HXMT/HE detected a long GRB 251128A, which is also detected by Fermi/GBM (Fermi GBM Team, GCN #42865Loading...
 
 ).

The Insight-HXMT/HE light curve mainly consists of multiple pulses with a T90 of 44 +11/-18 s. The 1s peak rate, measured from T0+9.5 s, is 604 cnts/sec. Insight-HXMT/HE detected a total of 3694 counts from this burst.

The Insight-HXMT/HE light curve can be found here:
https://www.bursthub.cn//admin/static/hxmtgrb251128A.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

GCN Circular 42881

Subject

GRB 251128A: Fermi GBM Observation

Date

2025-11-29T03:48:05Z (a day ago)

From

rhamburg@usra.edu

Via

Web form

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 42865Loading...
 
 ), which was also detected by Swift/BAT-GUANO (DeLaunay et al. 2025, GCN 42874Loading...
 
 ).

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/"

GCN Circular 42874

Subject

GRB 251128A: Swift/BAT-GUANO localization skymap of a burst

Date

2025-11-28T21:14:53Z (a day ago)

From

Jimmy DeLaunay at Penn State <delauj2@gmail.com>

Via

Web form

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

The probability skymap and joint skymap files can be downloaded from the links here

skymap_fits_file

joint_skymap_fits_file

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/

GCN Circular 42873

Subject

Fermi GRB 251128A: Global MASTER-Net observations report

Date

2025-11-28T15:15:24Z (2 days ago)

From

Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

Via

V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, 
G.Antipov,  A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU),
O.Gress, N.Budnev (ISU),
C.Francile,  F. Podesta, R.Podesta, E. Gonzalez  (Observatorio Astronomico Felix Aguilar (OAFA),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A.Sosnovskij (CrAO),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity),
D.Buckley (SAAO),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) 

MASTER-Kislovodsk robotic telescope  [1]  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 251128A ( Fermi GBM team, GCN 42865Loading...
 
 ) errorbox  36273 sec after notice time and 36305 sec after trigger time at 2025-11-28 14:27:27 UT, with upper limit up to  16.6 mag. Observations started at twilight.  The observations began at zenith distance = 80 deg. The sun  altitude  is -9.0 deg. 

The galactic latitude b = 30 deg., longitude l = 166 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=3053740

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   36336 | 2025-11-28 14:27:27 |   MASTER-Kislovodsk | (07h 48m 24.78s , +54d 16m 19.6s) |   C |    60 | 12.8 |        
   36336 | 2025-11-28 14:27:27 |   MASTER-Kislovodsk | (07h 55m 11.13s , +53d 52m 14.4s) |   C |    60 | 15.7 |        
   36496 | 2025-11-28 14:30:07 |   MASTER-Kislovodsk | (07h 27m 49.20s , +52d 20m 52.7s) |   C |    60 | 13.1 |        
   36496 | 2025-11-28 14:30:07 |   MASTER-Kislovodsk | (07h 34m 27.48s , +51d 56m 56.6s) |   C |    60 | 16.0 |        
   36575 | 2025-11-28 14:31:27 |   MASTER-Kislovodsk | (07h 44m 12.06s , +56d 08m 56.4s) |   C |    60 | 13.4 |        
   36575 | 2025-11-28 14:31:27 |   MASTER-Kislovodsk | (07h 51m 27.99s , +55d 44m 39.4s) |   C |    60 | 16.3 |        
   36655 | 2025-11-28 14:32:46 |   MASTER-Kislovodsk | (07h 29m 20.17s , +53d 53m 04.8s) |   C |    60 | 16.6 |        
   37136 | 2025-11-28 14:40:47 |   MASTER-Kislovodsk | (07h 59m 24.43s , +51d 57m 45.1s) |   C |    60 | 16.3 |        
   37136 | 2025-11-28 14:40:47 |   MASTER-Kislovodsk | (07h 52m 49.54s , +52d 22m 11.6s) |   C |    60 | 13.5 |        
   37608 | 2025-11-28 14:48:39 |   MASTER-Kislovodsk | (07h 39m 46.04s , +50d 04m 30.2s) |   C |    60 | 16.5 |        
   37608 | 2025-11-28 14:48:39 |   MASTER-Kislovodsk | (07h 33m 24.33s , +50d 28m 49.0s) |   C |    60 | 14.3 |        
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

GCN Circular 42865

Subject

GRB 251128A: Fermi GBM Final Real-time Localization

Date

2025-11-28T04:33:00Z (2 days ago)

From

Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

Via

The Fermi GBM team reports the detection of a likely LONG GRB

At 04:22:21 UT on 28 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251128A (trigger 785996546.612178 / 251128182).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 117.5, Dec = 52.2 (J2000 degrees, equivalent to J2000 07h 49m, 52d 12'), with a statistical uncertainty of 2.0 degrees.

The angle from the Fermi LAT boresight is 114.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251128182/quicklook/glg_skymap_all_bn251128182.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251128182/quicklook/glg_healpix_all_bn251128182.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251128182/quicklook/glg_lc_medres34_bn251128182.gif