GCN Circular 45951
GRB 261011A: SAO RAS and AbAO optical observations
From: Alexander Moskvitin at SAO RAS
Issued: 2026-10-14 16:33 UTC
A. Moskvitin (SAO), A. Volnova (IKI), V. Goranskij (SAI MSU, SAO),
V. Vlasyuk (SAO), R. Inasaridze (AbAO), N. Pankov (IKI), A. Pozanenko
(IKI),
on behalf of the SAO GRB follow-up team and the IKI-GRB-FuN report.
We observed the field of GRB 261011A (Huang et al., GCN 45895;
Cenko et al., GCN 45896; Ridnaia et al., GCN 45924; Barthelmy et al.,
GCN 45930; Page et al., GCN 45933; Melandri et al., GCN 45934;
Luo et al., GCN 45939) at redshift z = 2.407 (Pérez-García et al.,
GCN 45931; Monsalves et al., GCN 45920) with the SAO RAS 1-m Zeiss-1000,
0.5-m AS-500(2) and AbAO 0.7-m AS-32 telescopes on October 11.
The OT (Cenko et al., GCN 45896; O'Neill et al., GCN 45897; Fu et al.,
GCN 45898; Izzo, GCNs 45899; 45909; Wu et al., GCN 45900; Shi et al.,
GCN 45903; Aryan et al., GCN 45904; Saikia et al., GCN 45907;
Bochenek and Perley, GCN 45914; Li et al., GCN 45915; Zhao et al.,
GCN 45916; Takahashi et al., GCN 45917; Cheng et al., GCN 45922;
also observed in NIR by Huang et al., GCN 45913) is marginally
detected only in the Zeiss-1000 stacked frame.
Details of the observation are the following.
Date UT start t-T0 Exp, Filter Obj Err UL
Site/Telescope
(mid,days) (n*s) (3sigma)
2026-10-11 20:22:07 0.29806 117*30 R n/d 21.6
SAO/AS-500(2)
2026-10-11 20:56:50 0.30510 3*300 Rc 21.9 0.3 22.0
SAO/Zeiss-1000
2026-10-11 21:01:57 0.32050 49*60 R n/d 20.9
AbAO/AS-32
This preliminary photometry (Vega) is based on nearby SDSS stars
(Lupton 2005 transformation) and 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.
Transient Alerts » in reply to GRB 261011A — GRB, X-ray Transient
In plain words Notable
On 11 October 2026 two satellites, SVOM and Swift, caught a long gamma-ray burst (a brief flash of high-energy light from a distant exploding star) in the southern sky. It lasted roughly a minute or more, depending on the instrument. Within minutes, telescopes around the world saw a fading visible-light and X-ray afterglow at the same spot. Two large telescopes measured the distance from the light's fingerprints: the burst happened at redshift 2.407, meaning the light left roughly 11 billion years ago. The afterglow faded below detection within about a day, and no host galaxy has been clearly detected. It is most likely an ordinary long burst from the collapse of a massive star. Swift's first report of an unusual light curve was withdrawn after a closer look showed that part of it came from noisy detectors.
How unusual is it? Most gamma-ray bursts have no measured distance, but this one has a confirmed redshift (2.407) from two independent telescopes plus a bright afterglow seen in many wavelengths; otherwise its properties look typical, and the initially reported oddity turned out to be instrumental noise.
Written by an AI model (claude-sonnet-5-5) from the official reports in this thread, and rewritten as new reports arrived (version 9); last updated . It may contain mistakes: the reports themselves are the authority.
GRB 261011A: SAO RAS and AbAO optical observations
The whole thread (32 posts)
- GRB 261011A — GRB, X-ray Transient
- GRB 261011A: 1.3m DFOT optical upper limit
- GRB 261011A: SAO RAS and AbAO optical observations
- GRB 261011A: Later-epoch J-band upper limit from the SYSU 80 cm infrared telescope
- GRB 261011A: GECAM-B observation
- GRB 261011A: Swift-XRT refined Analysis
- GRB 261011A: Enhanced Swift-XRT position
- GRB 261011A: 10.4m GTC spectroscopic redshift (z = 2.407)
- GRB 261011A: Swift-BAT refined analysis
- GRB 261011A: REM optical/NIR observations
- Konus-Wind detection of GRB 261011A
- Updated explainer: what the latest reports add (AI-written)
- GRB 261011A: SOAR optical afterglow observations at ~17 hours
- GRB 261011A: VLT/X-shooter redshift constraints
- GRB 261011A : MITSuME Akeno optical afterglow candidate detection
- GRB 261011A: Optical followup from Sichuan South Observatory
- GRB 261011A: GMG Optical Observation
- GRB 261011A: Liverpool Telescope optical observations
- GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
- GRB 261011A: continued LCO optical observations
- GRB 261011A: GROWTH-India Telescope optical observations
- GRB 261011A: Optical upper limits with a 28cm telescope in Chengde
- Swift GRB 261011A: Global MASTER-Net observations report
- GRB 261011A: Optical follow-up observations with Kinder
- GRB 261011A: SVOM/C-GFT optical observations
- GRB 261011A: LCO optical observations
- GRB 261011A: SVOM/VT optical observation from VHF data
- GRB 261011A: LCO optical observations
- GRB 261011A: TRT optical afterglow detection
- Explainer: what this is and why it matters (AI-written)
- GRB 261011A: GOTO optical counterpart detection
- GRB 261011A: Swift detection of an unusual burst