GRB 251213A
GCN Circular 43130
Subject
GRB 251213A: GRID-10B observation
Date
2025-12-15T16:43:28Z (2 days ago)
From
GRID Student Team at Tsinghua University <grid@tsinghua.edu.cn>
Via
Web form
Xiao-Fan Pan, Long-Hao Li, Chen-Yu Wang, Zi-Rui Yang report on behalf of the GRID Collaboration:
GRID reports the detection of GRB 251213A, a long-duration gamma-ray burst. The event triggered GRID-10B at T0 = 2025-12-13 12:30:04 UTC. The measured burst duration (10B) is T90 = 35.5 ± 3.2 s in the 30–2000 keV energy range. The event was also detected by GRID-11B (GCN #43116), GECAM-B (GCN #43106), SVOM/GRM (GCN $43111), and AstroSat CZTI (GCN #43108).
The GRID light curves for this event are available at https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB251213A/GRID_GRB251213A_ltcv.pdf.
GRID is a student-led project to monitor the transient gamma-ray sky with multiple detectors onboard different nanosatellites in the era of multi-messenger astronomy. For more information about GRID, please refer to the following references: https://doi.org/10.1007/s10686-019-09636-w and https://doi.org/10.1007/s10686-021-09819-4.
GCN Circular 43116
Subject
GRID detection of GRB 251213A
Date
2025-12-15T11:47:12Z (2 days ago)
From
GRID Student Team at Tsinghua University <grid@tsinghua.edu.cn>
Via
Web form
Long-Hao Li, Chen-Yu Wang, Zi-Rui Yang report on behalf of the GRID Collaboration:
GRID reports the detection of GRB 251213A, a long-duration gamma-ray burst, which was also detected by GECAM-B (GCN Circ.43106), SVOM/GRM and AstroSat CZTI (GCN Circ. 43108). The event triggered GRID-11B at T0 = 2025-12-13 12:30:04 UTC. The measured burst duration is T90 = 34.6 ± 2.8 s in the 30–2000 keV energy range.
The GRID light curve for this event is available at https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB251213A/GRID_GRB251213A_ltcv.pdf.
GRID is a student-led project to monitor the transient gamma-ray sky with multiple detectors onboard different nanosatellites in the era of multi-messenger astronomy. For more information about GRID, please refer to the following references: https://doi.org/10.1007/s10686-019-09636-w and https://doi.org/10.1007/s10686-021-09819-4.
GCN Circular 43111
Subject
GRB 251213A: SVOM/GRM observation
Date
2025-12-15T09:24:16Z (2 days ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
SVOM/GRM team: Chen-Wei Wang, Wen-Jun Tan, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Ulysse Jacob (LUPM)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by a burst GRB 251213A (SVOM trigger reference: sb25121302) at 2025-12-13T12:30:05.000 UTC (T0), which is also detected by GRID, GECAM-B (Wang et al., GCN#43106) and AstroSat (Harsha K. H. et al., GCN#43108).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multiple pulses with a T90 of 36.5 +1.0/-1.0 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb251213A.png
In addition, the position of this burst, as determined by GECAM-B (RA= 296.5, DEC= -11.9, ERR=5.6), is located at about 102 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view.
With this localization, the time-averaged spectrum from T0-5 to T0+45 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -0.95 +0.10/-0.09 and the cutoff energy, parameterized as Epeak, is 453 +63/-50 keV. The event fluence (10-1000 keV) in this time interval is (5.58 +0.18/-0.19)E-05 erg/cm^2.
The 1s peak spectrum, measured from T0+5.0 to T0+6.0 s, is also best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.09 +0.14/-0.12 and the cutoff energy, parameterized as Epeak, is 800 +286/-182 keV. The flux (10-1000 keV) in this time interval is (3.31 +0.13/-0.14)E-06 erg/cm^2/s.
The localization of GRB 251213A in the 'Amati' relation diagram is shown at:
https://www.bursthub.cn//admin/static/svgrb251213A_amati.png
And the localization in the 'Yonetoku' relation diagram is shown at:
https://www.bursthub.cn//admin/static/svgrb251213A_yonetoku.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 point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang@ihep.ac.cn)
GCN Circular 43108
Subject
GRB 251213A: AstroSat CZTI detection
Date
2025-12-15T06:37:41Z (2 days ago)
From
Gaurav Waratkar at Caltech <gauravwaratkar@iitb.ac.in>
Via
Web form
Harsha K. H. (IUCAA), S. Salunke (IUCAA), M. Tembhurnikar (IUCAA), A. Arya (IITB), A. Goyal (IITB), 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-duration GRB 251213A which was also detected by GECAM-B (Wang et. al., GCN Circ. 43106).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-12-13 12:30:11.00 UTC. The measured peak count rate associated with the burst is 48 (+18, -9) counts/s above the background in the combined data of three quadrants (out of four), with a total of 617 (+188, -211) counts. The local mean background count rate was 187 (+1, -2) counts/s. Using cumulative rates, we measure a T90 of 39 (+1, -14) 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 2025-12-13 12:30:12.01 UTC. The measured peak count rate associated with the burst is 265 (+71, -15) counts/s above the background in the combined data of all quadrants, with a total of 3624 (+653, -519) counts. The local mean background count rate was 1137 (+4, -6) counts/s. We measure a T90 of 36 (+1, -2) 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 43106
Subject
GRB 251213A: GECAM-B detection
Date
2025-12-15T06:05:28Z (2 days ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team:
GECAM-B was triggered in-flight by GRB 251213A, at 2025-12-13T12:30:05.050 UTC (denoted as T0), which is also detected by SVOM/GRM and GRID.
According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of a precursor followed by multi-pulses with a duration (T90) of 34.6 +1.0/-1.0 s.
The GECAM-B light curve can be found here:
https://www.bursthub.cn//admin/static/gecambgrb251213A.png
GECAM-B localized this burst to the following position (J2000):
Ra: 296.5 deg
Dec: -11.9 deg
Err: 5.6 deg (1-sigma, statistical only)
We note that the non-detection by Fermi/GBM suggests that the error box can be further constrained in the future.
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).