[vsnet-grb-info 20074] GRB 171123A: TShAO optical upper limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22169
SUBJECT: GRB 171123A: TShAO optical upper limit
DATE:    17/11/24 23:05:11 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

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

We observed the field of the Swift  GRB 171123A   (Evans et al.,
GCN  22148) with Zeiss-1000 1-m telescope of Tien Shan Astronomical 
Observatory starting on Nov., 23 (UT) 23:31:56.  We took several images 
in R-filter.  Within enhanced XRT error circle  (Goad et al., GCN 22150) 
we do not detect  any  object.  Preliminary  photometry of the afterglow 
is following

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

2017-11-23 23:31:56  0.41294  R    38*120  n/d    n/d  22.2

Photometry is based on nearby USNO-B1.0 stars, R2 magnitude.