GCN Circular 45837
GRB 261007A / EP261007a: LCO optical observations
From: SVOM_group
Issued: 2026-10-07 15:16 UTC
Type: GRB, X-ray Transient, Optical Transient
A. Saccardi (CEA/Irfu), D. Turpin (CEA/Irfu), S. J. Yin (GXU), C. Wu (NAOC), W. Zhang(PMO), X. Tian (GXU), report on behalf of the SVOM mission team:
We observed the optical counterpart (Zheng et al., GCN 45825; Mohan et al., GCN 45832; Saccardi et al., GCN 45829) of the SVOM/ECLAIRs GRB 261007A / EP261007a (Goto et al., GCN 45824), also detected by EP/WXT (Wen et al., GCN 45828) and Fermi/GBM (Malacaria, GCN 45830), with the LCO 1m telescope at Siding Spring Observatory equipped with the Sinistro instrument.
Our observation started on 2026-10-07 at 13:00:16 UT (about 7.3 hr after the trigger) and we obtained 3x200 s exposures in the SDSS r filter.
The optical candidate is well detected in our images. We measure the following magnitude calibrated against the Pan-STARRS DR1 catalog, and not corrected for Galactic extinction:
r = 19.78 +/- 0.08 AB (mid-time 7.33 hr after the trigger).
This project is funded by the SVOM collaboration.
Every one of the gamma-ray bursts GCN reports is posted here.
Relayed automatically from NASA's General Coordinates Network.
Transient Alerts » in reply to GRB 261007A — GRB, X-ray Transient
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.
The whole thread (18 posts)
- GRB 261007A — GRB, X-ray Transient
- GRB 261007A: AstroSat CZTI detection
- GRB 261007A/EP261007a: Optical follow-up observations with Kinder
- GRB 261007A / EP261007a: SVOM/VT optical observations
- GRB 261007A: Swift-XRT afterglow detection
- GRB 261007A: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 261007A / EP261007a: NuSTAR detection of prompt emission
- GRB 261007A / EP261007a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at McDonald Observatory
- Autonomous identification and follow-up of the counterpart to GRB 261007A by BTSbot with ZTF and P60/SEDM
- GRB 261007A: GROWTH-India Telescope optical observations
- GRB 261007A / EP261007a: TRT optical observations
- GRB 261007A: Swift ToO observations
- GRB 261007A: SVOM/C-GFT optical observations
- GRB 261007A / EP261007a: LCO optical observations
- GRB 261007A: WINTER J-band observations
- GRB 261007A: Fermi GBM observation
- GRB 261007A / EP261007a: VLT/X-shooter spectroscopic redshift z = 2.101
- GRB 261007A: KAIT optical counterpart candidate
