TITLE:   GCN CIRCULAR
NUMBER:  22175
SUBJECT: GRB 171124A: TShAO optical observations
DATE:    17/12/01 12:48:25 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the field  of the Fermi/LAT-detected burst GRB 171124A 
(Longo et al. GCN   22156) with Zeiss-1000 1-m telescope of Tien Shan 
Astronomical Observatory starting on Nov. 27 (UT) 12:28:32. We took 
several images in R-filter with exposures of 120 s. We cover all LAT- 
localization region.
The three XRT sources ## 1,3,4 (Osborne  et al. GCN   22165)  are 
detected in our stacked image. These sources are also presented in the 
USNO-B1.0 catalogue. We do not detect any optical object within X-ray 
afterglow (XRT #2 error circle, Osborne  et al. GCN  22174).  We may 
note that 4.5 arcsec South of XRT #2    we detect a galaxy which is also 
present in USNO-B1.0.

Preliminary photometry of the field is following:

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

2017-11-27 12:28:32  3.31825  R    40*120  n/d  n/d  22.0

The  finding chart of the 32 XRT source  can be found at
http://grb.rssi.ru/GRB171124A/GRB171124A_XRT2.png

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

USNO-B.1_id R2
1251-0500105 14.64
1252-0499091 16.06
1251-0500220 15.86
1251-0500271 16.17
1251-0500270 16.12
1251-0500372 16.06