GCN Circular 46018
Subject
EP261023a: Mondy optical upper limit
Event
Date
2026-10-24T09:07:49Z (3 days ago)
From
Nicolai Pankov at Independent Researcher <colinsergesen@gmail.com>
Via
Web form
N. Pankov (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Moskvitin (SAO RAS), A. Volnova (IKI) report on behalf of IKI-GRB-FuN:
We observed the field of the Einstein Probe fast X-ray transient EP261023a (Yang et al., GCN 46014) with the 1.5-m AZT-33IK telescope of Sayan Solar Observatory (Mondy). Observations started on 2026-10-23 at 13:30:00 UT, i.e. ~0.41 days after the EP/WXT trigger. A series of 30x120 s frames was obtained in the R filter.
The optical counterpart (Lei et al., GCN 46015 and 45972) is not detected in the co-add frame from Mondy. Preliminary upper limit and observation details are given below.
Date UTstart t-T0 Exp. Filter OT Err. UL
(mid, days) (s) (3sigma)
2026-10-23 13:30:00 0.41437 30x120 R n/d n/d 22.2
The photometry was calibrated against nearby USNO-B1.0 stars (R2 magnitudes) and is not corrected for Galactic extinction.