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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: WINTER J-band observations
GCN Circulars —

GCN Circular 45832
GRB 261007A: WINTER J-band observations
From: unknown
Issued: 2026-10-07 10:54 UTC
Type: GRB

Tanishk Mohan (IITB), Benjamin Schneider (LAM), Geoffrey Mo (Caltech/Carnegie), Viraj Karambelkar (Columbia), Tomas Ahumada (NOIRLab), Robert Stein (UMD), Danielle Frostig (CfA), Nathan Lourie (MIT), Robert Simcoe (MIT), and Mansi Kasliwal (Caltech) report:

We observed the field of GRB 261007A (Goto et al., GCN 45824; also see Wen et al., GCN 45828 and Malacaria et al., 45830) in the near-infrared J band with the Palomar 1-m telescope, equipped with the 1.2-square degree WINTER camera (Lourie et al. 2020, Frostig et al. 2024).

Observations began on 2026-10-07 at 06:10:56.150 UTC in the J band (28.9 min after the SVOM/ECLAIRs trigger), consisting of 15*120 sec exposures. The images were processed using the WINTER data reduction pipeline implemented with mirar (GitHub - winter-telescope/mirar: Modular Image Reduction and Analysis Resource (MIRAR) (github.com), winter-telescope/mirar: v0.17.0 (doi.org)).

We detect a bright source present at the optical counterpart position (Zheng et al., GCN 45825; Saccardi et al., GCN 45829) in our stacked image.
We obtain the following magnitude: J = 17.36 +- 0.06 mag (AB) in our stacked image.
We also note that the source has faded by ~0.5 mag between our first and last exposure during the observation (in about 28 min).

WINTER (Wide-field INfrared Transient ExploreR) is a partnership between MIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF AAG, the David and Lucile Packard Foundation, and the MIT Kavli Institute for Astrophysics and Space Research.

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

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