GCN Circular 45933
GRB 261011A: Enhanced Swift-XRT position
From: K.L. Page at U Leicester
Issued: 2026-10-13 07:11 UTC
K.L. Page, P.A. Evans and M.R. Goad (U. Leicester) report
on behalf of the Swift-XRT team:
Using 1938 s of XRT Photon Counting mode data and 4 UVOT images, we find
an astrometrically corrected X-ray position (using the XRT-UVOT alignment
and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec =
21.89722, -21.56052 which is equivalent to:
RA (J2000): 01 27 35.33
Dec (J2000): -21 33 37.9
with an uncertainty of 2.9 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at UKSSDC | Swift-XRT GRB positions (swift.ac.uk). Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.
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 Swift's first report of an unusual light curve was withdrawn after a closer look showed that part of it came from noisy detectors.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: Enhanced Swift-XRT position
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