TITLE:   GCN CIRCULAR
NUMBER:  35952
SUBJECT: X-ray transient EP240315a/AT2024eju: TShAO (Zeiss-1000) observatory optical upper limit
DATE:    24/03/18 14:52:47 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

N. Pankov (HSE, IKI), I. Reva (FAI), A. Pozanenko (IKI), S. Belkin (IKI), A. Volnova (IKI) report on behalf of IKI GRB FuN:

We observed the field of the X-ray transient EP240315a (Zhang et al., GCN 35931) till  now also detected by Follow-up X-ray Telescope  of Einstein Probe (Chen et al., GCN 35951). The optical counterpart AT2024eju discovered by ATLAS (Srivastav et al., GCN 35932, 35933) and observed in optic (Jiang et al., GCN 35935; Saccardi et al., GCN 35936; Rau GCN 35937; Chen GCN 35938; Leonini et al., GCN 35944; Pankov et al., GCN 35945) was observed with Zeiss-1000 telescope of Tien Shan Astronomical Observatory stating on 2024-03-17 (UT) 14:12:06 in R filter. We do not detect the optical counterpart. Preliminary photometry of the filed is following

Date       UT start   t-T0    Filter Exp.    OT     Err.  UL(3sigma)
                      (mid, days)    (s)

2024-03-17 14:12:06  1.77526   R     35*120  n/d    n/d   22.3

The photometry is based on nearby USNO-B1.0 (R2) stars.