TITLE:   GCN CIRCULAR
NUMBER:  41024
SUBJECT: GRB 250704B / EP250704a: Mondy and AbAO optical observations
DATE:    25/07/08 12:26:15 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <grb.alex@gmail.com>

 A. Volnova (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), R. Ya. Inasaridze
(AbAO), N. Pankov (HSE) report on behalf of GRB IKI FuN:

We observed the field of the EP250704a (Li et al., GCN 40941) also detected
by SVOM (GRB 250704B; Wang et al., GCN 40940) with AZT-33IK telescope of
Mondy observatory in R-filter on 2025-07-05 and with AS-32 telescope of
Abastumani observatory on 2025-07-05. The optical afterglow (Li et al.,
GCNs 40941; Schneider et al., GCN 40942; Malesani et al., GCN 40945; Brivio
et al., GCN 40947; Evans et al., GCN 40951; Perez-Garcia et al., GCN 4957;
Gillanders et al., GCN 40958; Xin et al., GCN 40960; Mohan et al., GCN
40962; Moskvin et al., GCN 40963; Liu et al., GCN 40965; An et al., GCN
40966; Yang et al., GCN 4970; Martin-Carillo et al., GCN 40971; Frederiks
et al., GCN 40972,Malte Busmann et al., GCN 40974, Li et al., GCN40975, Li
et al., GCN 40986; An et al., GCN 40993; Wang et al., GCN 40999).

We detect the afterglow  on 2025-07-05. Preliminary photometry of a stacked
image is the following

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

2025-07-05|16:34:49| 1.36693| 30*120 |R|21.06 |0.05| 22.9 |AZT-33IK
2005-07-06|19:39:17| 2.51241| 52*60 |R|n/d |- | 21.2 |AS-32

The photometry is based on nearby reference stars from PS1 (Lupton
transformations)

RA Dec R_Lupton
20:03:37.87 +12:01:59.6 17.385
20:03:26.50 +12:02:18.5 17.436
20:03:24.72 +11:59:09.1 16.41