TITLE:   GCN CIRCULAR
NUMBER:  45394
SUBJECT: EP260812a: AbAO optical upper limit
DATE:    26/08/18 14:36:58 GMT
FROM:    Nicolai Pankov at IKI <colinsergesen@gmail.com>

N. Pankov (IKI), R. Ya. Inasaridze (AbAO), A. Pozanenko (IKI), M. Zhuzhunadze 
(AbAO) report on behalf of IKI-GRB-FuN:

We observed the field of the Einstein Probe fast X-ray transient EP260812a 
(Liu et al., GCN 45362) with the AS-32 telescope of Abastumani Observatory 
(AbAO). The observations were conducted on 2026-08-13 starting at 17:12:50 UT, 
i.e. ~1.267 days since trigger. The series of 66x60 sec exposures was taken in 
the R-filter using CCD-photometer. No new sources was identified within the 
X-ray error circle (Yang et al., GCN 45373). A faint optical source found in 
the NOT and LT observations (Corcoran et al., GCN 45376) is not detected in our 
observations. The observation summary and preliminary upper limit are 
provided below:

Date        UTstart    t-T0    Exp.   Filter     UL
                     (mid, d) (n*s)           (3sigma)     
2026-08-13  17:12:50 1.26723   65x60    R       22.1

The photometry is based on nearby USNO-B1.0 stars (R2 magnitudes) and has not 
been corrected for the Galactic extinction. Our results are consistent with the 
upper limits reported by Yin et al. (GCN 45372), Corcoran et al. (GCN 45376), 
and Mirzakulov et al. (GCN 45387).