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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 detected on 7 October 2026 by SVOM, a China-France satellite, and by several other space telescopes, including Fermi, NuSTAR, AstroSat and the Einstein Probe. It came from a spot in the southern sky and lasted about 23 seconds, which makes it a long gamma-ray burst, the kind usually linked to the death of a massive star. Within minutes, ground telescopes found a fading optical afterglow, and Swift later detected an X-ray afterglow at the same position. A large telescope in Chile (the VLT) measured the distance from the afterglow's light: the explosion happened about 2.1 in redshift, meaning the light left roughly 10 billion years ago. The afterglow was bright at first, around magnitude 15 within two minutes, and had faded to about magnitude 21 a day later, as expected.

How unusual is it? A spectroscopic redshift (z = 2.101) and a bright optical afterglow caught within minutes and followed in X-rays by many telescopes make this better studied than most of the few hundred bursts seen each year, but the burst itself looks like a typical long gamma-ray burst, not a record-breaker.

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

GRB 261007A: NOT optical observations
GCN Circulars —

GCN Circular 45865
GRB 261007A: NOT optical observations
From: unknown
Issued: 2026-10-08 16:07 UTC
Type: GRB, Optical Transient

D. O’Neill (Birmingham), D. B. Malesani (DAWN/NBI), A. S. Mårtensson (NOT), A. Caballero Almagro (NOT), report on behalf of a larger collaboration:

We observed the optical counterpart (Zheng et al., GCN 45825; Saccardi et al., GCN 45829; Mohan et al., GCN 45832; Saccardi et al., GCNs 45837, 45837; Shi et al., GCN 45838; An et al., GCN 45840; Arya et al., GCN 45841; Rehemtulla et al., GCN 45843; Ruiz-Laguna et al., GCN 45844; Angulo et al., GCN 45848; Li et al., GCN 45851; Chen et al., GCN 45855; Zhang et al., GCN 45856) of GRB 261007a/EP261007a (Fermi GBM team, GCN Circ. 45830; SVOM/ECLAIRs: Goto et. al., GCN Circ. 45824; SVOM/GRB: Ren et al., GCN 45863; Einstein Probe: Wen et. al., GCN Circ. 45828; NuSTAR: Waratkar et. al., GCN Circ. 45846; AstroSat CZTI: Harsha et. al., GCN 45859) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC instrument. Observations were performed starting at 01:38:38 UT on October 8 2026 (about 20 hr after SVOM trigger), and consisted of 3x300 s in the SDSS-r band.

In our stacked images we measure an AB magnitude:

r = 21.36 ± 0.04

This magnitude is calibrated using nearby objects from the Pan-STARRS catalog and is not corrected for Galactic extinction.

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

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