GCN Circular 42950
Subject
GRB 251122A/EP251122a: CrAO ZTSh optical observations
Event
Date
2025-12-02T15:21:45Z (a day ago)
From
Alina Volnova at IKI RAS <alinusss@gmail.com>
Via
Web form
A. A. Volnova (IKI), V. V. Rumyantsev (CrAO), A. S. Pozanenko (IKI), N. S. Pankov (IKI) report on behalf of IKI GRB-FuN collaboration:
We observed the FXT localization of GRB 251122A/EP251122a (Wang et al., GCN 42779; Lin et al., GCN 42800; Yin et al., GCN 42808; Wang et al., GCN 42809) with the ZTSH telescope of CrAO starting on 2025-11-11 (UT) 21:37:17 UT and taking several 120s exposures in R-band. The optical counterpart (Cheng et al., GCN 42803; Li et al., GCN 42806; Sun et al., GCN 42807; Ma et al., GCN 42811; Gupta et al., GCN 42813; Busmann et al., GCN 42814) is detected in the stacked frame. Preliminary photometry is the following:
Date UT start t-T0 Exp. Filter OT Err. UL Site/Instrum
(mid,days) (n*s) (3sigma)
2025-11-22 21:37:17 0.34097 20*120 R 22.36 0.25 22.8 CrAO/ZTSh
The photometry is based on nearby stars from the USNO-B1 catalogue (R2 magnitudes) and is not corrected for the Galactic extinction.