GCN Circular 45997
Subject
EP261015a: Terskol Zeiss-2000 optical upper limit
Event
Date
2026-10-20T15:07:34Z (20 hours ago)
From
Alina Volnova at IKI RAS <alinusss@gmail.com>
Via
Web form
A. Volnova (IKI), D. Andreev (INASAN), A. Pozanenko (IKI), A. Moskvitin (SAO), N. Pankov (IKI) report on behalf of IKI-GRB-FuN:
We observed the field of Einstein Probe fast X-ray transient EP261015a (Li et al., GCN 45956) with the Zeiss-2000 2-meter telescope of the Terskol Observatory on Oct. 17, 2026, starting at 21:30 UT and taking several exposures in R-band.
The optical counterpart reported previously (Corcoran et al., GCNs 45955, 45972; Fortin et al., GCN 45991) is not detected in the stacked frame.
Preliminary photometry and observational details are the following:
Date UT start t-T0 Exp, Filter Obj Err UL Site/Telescope
(mid,days) (n*s) (3sigma)
2026-10-17 21:30:24 2.32810 20*180 R n/d n/d 22.8 Terskol/Z2000
The photometry is based on several nearby stars from the USNO-B1 catalogue (R2 magnitudes) and is not corrected for the Galactic extinction.