TITLE:   GCN CIRCULAR
NUMBER:  23789
SUBJECT: GRB 190123A: IKI-GRB-FuN optical upper limit
DATE:    19/01/24 17:24:58 GMT
FROM:    Alina Volnova at SAI MSU  <alinusss@gmail.com>

A. Volnova (IKI), A. Pozanenko (IKI),  E. Mazaeva (IKI),  E. Klunko
(ISTP), A. Kusakin (FAPHI), I. Reva  (FAPHI), R. Inasaridze (AAO),
A. Ivanov (KubSU), S. Belkin (IKI)  report on behalf of IKI-GRB-FuN:

We observed the field of GRB 190123A (D'Ai et al., GCN 23769)
on Jan., 23 with Zeiss-1000 1-m telescope of Tien Shan Astronomical
Observatory starting on 13:38:38, with MC 0.25-meter telescope of
Kuban State University Astrophysical observatory starting on 15:09:35
UT, with AS-32 (0.7m) telescope of Abastumani Observatory starting on
16:12:18 UT, and with AZT-33IK telescope of Sayan observatory (Mondy)
starting on 18:24:05 UT. We took several frames in R band with every
listed telescope.

We do not detect any source at the enhanced XRT position (Beardmore et
al., GCN 23771) in stacked images of each observatory.

Preliminary photometry of AZT-33IKI observations is based on several
nearby USNO-B1.0 stars:

Date            UT_start   t-T0            Filter    Exp.   OT   UL(3sigma)
                                    (mid, days)             (s)
2019-01-23 18:24:05   0.28248      R         4980  n/d   22.5

Our non-detection is consistent with non-detections reported by Lipunov
et al. (GCN 23770), Hu et al. (GCN 23772), Steeghs et al. (GCN 23774),
Shiraishi et al.(GCN 23778), Watson et al. (GCN 23781), Siegel et al.
(GCN 23784), and Nakamura & Sakamoto (GCN 23786).