[vsnet-grb-info 24516] GRB 191228A: Mondy optical upper limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26615
SUBJECT: GRB 191228A: Mondy optical upper limit
DATE:    19/12/30 15:53:01 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov (HSE), K. Kamyshnikov 
(HSE), E. Mazaeva (IKI), A. Volnova (IKI) report   on behalf of IKI-GRB-FuN:

We observed the field of  GRB 191228A (Bernardini et al.  GCN 26601) 
with AZT-33IK telescope of Sayan observatory (Mondy) starting on Dec. 28 
(UT)  11:15:09.   We  do not detect any optical object in the Enhanced 
Swift-XRT position  (Evans et al.  GCN 26606). Preliminary photometry of 
the field  is following.

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

2019-12-28 11:15:09    0.48923    R     30*120  n/d      20.1

Photometry is based on the USNO-B2.0 nearby stars.