TITLE:   GCN CIRCULAR
NUMBER:  22301
SUBJECT: GRB 180102A: TSHAO optical upper limit
DATE:    18/01/03 17:34:05 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Pozanenko (IKI), I. Reva (FAPHI), M. Krugov 
(FAPHI),  A. Volnova (IKI), A. Kusakin (FAPHI) report on behalf of 
larger GRB follow-up collaboration:

We observed the field of GRB 180102A (Page  et al., GCN 22292)   with 
Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory starting 
on Jan. 02 (UT) 21:34:54. We took several images in R-filter.  We do not 
detect any new sources within enhanced XRT error circle (Beardmore et 
al., GCN 22294).  Preliminary photometry of the field is following.

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

2018-01-02  21:34:54 0.25428  R      21*120  n/d   n/d   20.6


The photometry is based on several nearby USNO-B1.0 stars.