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Transient Alerts » in reply to GRB 261007A — GRB, X-ray Transient

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In plain words Notable

A burst of gamma rays (the most energetic form of light) was caught on 7 October 2026 by the SVOM satellite, Fermi, and several other space telescopes. It came from a patch of sky toward the constellation Cetus, and the Einstein Probe X-ray telescope also saw it. Within minutes, ground telescopes found a fading optical (visible-light) glow at the spot, and later X-ray and infrared detections confirmed it. A spectrum from the Very Large Telescope in Chile put the burst at redshift 2.101, which means the light left about 10 billion years ago. The burst lasted roughly 23 seconds, which fits the long kind of gamma-ray burst, usually produced when a massive star collapses. The glow faded from about magnitude 15 in the first minutes to about 21.6 a day later. That is a normal fading pattern for an afterglow.

How unusual is it? Most gamma-ray bursts have no measured distance, but this one has a secure spectroscopic redshift of 2.101 and a bright, well-followed afterglow seen in optical, infrared and X-ray light. That makes it notable, but it is otherwise an ordinary long burst, not one of the record-setters.

Written by an AI model (claude-sonnet-5-5) from the official reports in this thread, and rewritten as new reports arrived (version 4); last updated . It may contain mistakes: the reports themselves are the authority.

GRB 261007A: AstroSat CZTI detection
GCN Circulars —

GCN Circular 45859
GRB 261007A: AstroSat CZTI detection
From: ABHINAV GOYAL at Indian Institute of Technology Bombay
Issued: 2026-10-08 13:11 UTC
Type: GRB, Gamma-ray Transient, X-ray Transient

Harsha K. H. (IUCAA), S. Salunke (IUCAA), S. Puri (IITB), A. Goyal (IITB), A. Arya (IITB), G. Waratkar (Caltech/IITB), V. Bhalerao (IITB), A. Vibhute (IUCAA), 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 GRB 261007A which was also detected by Fermi (Fermi GBM team, GCN Circ. 45830), SVOM/ECLAIRs (Goto et. al., GCN Circ. 45824), associated with EP261007a detected by Einstein Probe (Wen et. al., GCN Circ. 45828), and NuSTAR (Waratkar et. al., GCN Circ. 45846).

The source was 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 2026-10-07 05:40:02.36 UTC. The measured peak count rate associated with the burst is 1427 (+79, -36) counts/s above the background in the combined data of all quadrants, with a total of 15823 (+333, -396) counts. The local mean background count rate was 307 (+3, -3) counts/s. We measure a T90 of 22.9 (+0.3, -0.4) s from the cumulative CZT light curve.

The source was clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2026-10-07 05:40:11.67 UTC. The measured peak count rate associated with the burst is 2125 (+88, -77) counts/s above the background in the combined data of all quadrants, with a total of 21607 (+536, -496) counts. The local mean background count rate was 772 (+6, -5) counts/s. We measure a T90 of 22.4 (+0.3, -0.3) s from the cumulative Veto light curve.

In the preliminary analysis, we find 1822 Compton events associated with this event.

CZTI data products like interactive and downloadable light curves for this GRB can be found at:
https://astrosat.iucaa.in/cift/cift_products/ET20261007T053949/ET20261007T053949_details.html

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

Every one of the gamma-ray bursts GCN reports is posted here.
Relayed automatically from NASA's General Coordinates Network.

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