TITLE:   GCN CIRCULAR
NUMBER:  23580
SUBJECT: GRB 181228A: TSHAO optical upper limit
DATE:    18/12/28 16:49:22 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the field of GRB 181228A (Moss et al., GCN 23570; 
Beardmoreet al., GCN 23574) with Zeiss-1000 1-m telescope of Tien Shan 
Astronomical Observatory starting on Dec. 28 (UT) 13:35:51.  We do not 
detected the OT   (D'Avanzo et al., GCN 23574; Lipunov et al. GCN 
23576). Preliminary photometry of the field is following.

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

2018-12-28 13:35:51 0.46359 R      21*120 n/d  n/d  21.7

The photometry is based on nearby USNO-B1.0 star
USNO-B1.0_id R2
1032-0046066 16.66