TITLE:   GCN CIRCULAR
NUMBER:  43894
SUBJECT: EP260227a: Mondy optical observations
DATE:    26/03/02 13:09:06 GMT
FROM:    Alina Volnova at IKI RAS <alinusss@gmail.com>

A. Volnova (IKI),  A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov (IKI)
 report on behalf of IKI-GRB-FuN:

We observed the field of the fast X-ray transient EP260227a (Wang et al.,
GCN 43869) with the AZT-33IK 1.5m telescope of the Mondy observatory
starting on 2026-02-28 (UT) 20:55:14 and taking several 90-seconds frames
in the R band. The optical counterpart (Eyles-Ferris et al., GCNs 43867,
43877, 43888; Li et al., GCN 43868; Fu et al., GCN 43873; Mandarakas et
al., GCN 43874; Eyles-Ferris and Tanvir, GCN 43875; Malesani et al., GCN
43876; Strausbaugh et al., GCN 43879; Bochenek et al., GCN 43880; Gassert
et al., GCN 43881; Gupta et al., GCN 43884; Ma et al., GCN 43887; Zhong et
al., GCN 43891) is barely detected in the stacked frame. Preliminary
photometry and observational details are the following:

Date        UT start  t-T0      Exp.    Filter Obj.   S/N  UL(3 sigma)
                     (mid,days) (n*s)                      (3sigma)
2026-02-28  20:55:14  1.05053   40*90   R      21.8   2.5   21.5

The photometry is based on several nearby stars from the USNO-B1 catalogue
(R2 magnitudes) and is not corrected for the Galactic extinction.