GCN Circular 45828
EP261007a/GRB 261007A: Einstein Probe detection of an X-ray transient
From: EP Team at NAOC/CAS
Issued: 2026-10-07 08:56 UTC
Type: GRB, X-ray Transient
Why this event is posted: every one of the gamma-ray bursts is posted.
W.F. Wen (SZTU), Q.H. Lao, H.Y. Liu (NAO, CAS), L.N. Xu (USTC), X.H. Tang (THU) and C.C. Jin (NAO, CAS) on behalf of the Einstein Probe (EP) team:
We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP261007a. The transient triggered EP-WXT (ID: 01709321003) at 2026-10-07T06:47:00 (UTC). The WXT position of the source is R.A. = 11.629 deg, DEC = -17.694 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic).
A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically. Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 11.6137 deg, DEC = -17.6933 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic).
We note that EP261007a is spatially consistent with GRB 261007A (GCN #45824, #45825). Further information will be updated when the telemetry data is received.
Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).
Every one of the gamma-ray bursts GCN reports is posted here.
Relayed automatically from NASA's General Coordinates Network.
In plain words Routine
A burst of X-rays was picked up by Einstein Probe, a Chinese-led space X-ray telescope, on 7 October 2026. The same spot on the sky was also linked to a gamma-ray burst seen by another satellite, SVOM. A follow-up X-ray telescope found a previously unknown X-ray source within the first position, which was in the southern sky at roughly right ascension 11.6 degrees, declination -17.7 degrees. About 8 hours after the trigger, a ground telescope at Xinglong Observatory in China detected a fading visible-light afterglow, about 20th magnitude, which is far too faint to see without a large telescope. Together these point to an ordinary gamma-ray burst, most likely from a distant exploding star. The reports give no distance yet, and no data on how long or how bright the burst was.
How unusual is it? A gamma-ray burst with an X-ray and optical afterglow is typical, since Fermi and Swift report a few hundred bursts a year and many have afterglows. A measured distance (redshift) or unusual brightness or duration would make it notable.
Written by an AI model (claude-sonnet-5-5) from the official reports in this thread, and rewritten as new reports arrived (version 2); last updated . It may contain mistakes: the reports themselves are the authority.
EP261007a — GRB, X-ray Transient