TITLE:   GCN CIRCULAR
NUMBER:  39576
SUBJECT: EP250302a: SAO RAS optical observations
DATE:    25/03/03 16:32:59 GMT
FROM:    Moskvitin Alexander at SAO RAS <mosk@sao.ru>

A. S. Moskvitin, O. A. Maslennikova (SAO RAS), A. Pozanenko (IKI) 
and N. Pankov (HSE, IKI) report on behalf of larger collaboration.

We observed the field of the X-ray transient EP250302a (Dai et al., 
GCN 39556; Page et al., GCN 39557) with SAO RAS 1-m telescope 
Zeiss-1000 equipped with CCD-photometer under mediocre weather 
conditions. We obtained two sets of 300-sec images in Rc band.
1st set: 2025.03.02, 20:33:49 -- 2025.03.02, 22:09:49 UT 
(t_mid - T0 = 0.24010 days = 5.7625 hours);
2nd set: 2025.03.02, 23:55:53 -- 2025.03.03, 01:00:10 UT, 
(t_mid - T0 = 0.36942 days = 8.8660 hours).

The OT (Zhu et al., GCN 39550; Busmann et al., GCN 39551; 
Leonini et al., GCN 39553; Wu et al., GCN 39555; Xin et al., 
GCN 39558; Adami et al., GCN 39560; Yang et al., GCN 39561;
Becerra et al., GCN 39562; Izzo et al., GCN 39564; Pankov et al., 
GCN 39565; Reguitti, GCN 39568; Komesh et al., GCN 39569; Shilling 
and Breeveld, GCN 39570; Aryan et al., GCN 39572) is clearly detected 
in our stacked frames with the following brightness.

Date       UT start t-T0 (mid),d   Exp.,s  Filter OT    Err. UL(3sigm)
2025.03.02 20:33:49 0.24010        8x300   R      20.18 0.09 22.5
2025.03.02 23:55:53 0.36942        7x300   R      20.51 0.10 22.5

Above photometry is preliminary and calibrated against R2 magnitudes 
of nearby USNO-B1 stars and not corrected for the Galaxy extinction.