TITLE:   GCN CIRCULAR
NUMBER:  36187
SUBJECT: EP240414A: Terskol Zeiss-2000 optical upper limit
DATE:    24/04/19 17:52:39 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

S. Belkin (IKI),  I. Sokolov (INASAN, KIAM), A. Pozanenko (IKI), N. Pankov (HSE) report on behalf of GRB IKI FuN:

We observed the EP240414A (Lian et al., GCN 36091) with the Zeiss-2000 telescope of Terskol observatory in R-filter on 2024-04-15 starting (UT) 22:55:21. We did not detect the optical counterpart (Aryan et al., GCN 36094; Xu et al., GCN 36105; Jonker et al., GCN 36110; Xiong et al., 36130; Srivastav et al., GCN 36150; Li et al., GCN 36154; Wang et al., GCN 36171;) down to the limiting magnitude of R~22.0. Preliminary photometry of a stacked image is the following

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

2024-04-15  22:55:21   1.56347   35x90  R        n/d  n/d   22.0

The photometry is based on nearby USNO-B1.0 stars.
USNO-B1.0
RA DEC R2
12:46:00.7214400 -09:43:21.021600 17.15
12:45:53.8893600 -09:43:46.700400 15.87
12:46:03.7461600 -09:41:28.521600 15.12