GRB 251010A
GCN Circular 42200
Subject
GRB 251010A: AstroSat CZTI detection
Date
2025-10-11T12:09:34Z (a day ago)
From
Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com>
Via
Web form
A. Goyal (IITB), A. Arya (IITB), U. Pathak (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 GRB 251010A which was also detected by Fermi GBM (GCN Circ. 42192).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed a broad peak of emission with the strongest peak at 2025-10-10 17:44:27.50 UTC. The measured peak count rate associated with the burst is 82 (+38, -8) counts/s above the background in the combined data of all quadrants, with a total of 628 (+155, -170) counts. The local mean background count rate was 292 (+3, -4) counts/s. Using cumulative rates, we measure a T90 of 9.5 (+3.1, -2.3) s.
The source was also faintly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.
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 42192
Subject
GRB 251010A: Fermi GBM Final Real-time Localization
Date
2025-10-10T17:55:05Z (2 days ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 17:44:25 UT on 10 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251010A (trigger 781811070.725816 / 251010739).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 214.0, Dec = 56.6 (J2000 degrees, equivalent to J2000 14h 16m, 56d 36'), with a statistical uncertainty of 4.5 degrees.
The angle from the Fermi LAT boresight is 103.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251010739/quicklook/glg_skymap_all_bn251010739.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/bn251010739/quicklook/glg_healpix_all_bn251010739.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251010739/quicklook/glg_lc_medres34_bn251010739.gif