TITLE:   GCN CIRCULAR
NUMBER:  43733
SUBJECT: EP260213a: Mondy R-band optical upper limit
DATE:    26/02/14 10:48:57 GMT
FROM:    Nicolai Pankov at IKI <colinsergesen@gmail.com>

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

We observed the field of a fast X-ray transient EP260213a (Yang et al., GCN 43729) with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy) starting on 2026-02-13 20:08:15 (UT). A total of 30x120 sec exposures were taken in the R-band. No optical candidate was detected within refined error circle (Li et al., GCN 43730). Also, no objects from the catalogues (SDSS, PS1, WISE, LS) were found within the error circle. The preliminary photometry and observational details are presented below:

Date       UT start  t-T0        Exp.    Filter Mag.  Err.  UL      
                     (mid,days)  (n*s)                     (3sigma)
2026-02-13 20:08:15  0.02797     30*120  R      n/d   n/d   22.2

The photometry was calibrated using nearby stars of USNO-B1.0 and has not been corrected for the Galactic extinction. Our results are consistent with the results published previously (Cotter et al., GCN 43728; Wu et al., GCN 43731; Maksut et al., GCN 43732).