[vsnet-grb-info 20150] GRB 171212A/Swift J1935.7+2036: TSHAO optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22246
SUBJECT: GRB 171212A/Swift J1935.7+2036: TSHAO optical observations
DATE:    17/12/12 19:18:46 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

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

We observed the field of GRB 171212A (Tohuvavohu  et al., GCN 22243) 
with Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory 
starting on Dec. 12 (UT) 12:21:15. We took several images in R-filter. 
Within enhanced Swift-XRT error circle   (Evans et al. GCN 22245)  we do 
not detect any object. Preliminary photometry of initial combined images 
is following.

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

2017-12-12  12:21:15 0.01896  R      3*120  n/d  n/d  20.0
2017-12-12  12:21:15 0.02728  R     13*120  n/d  n/d  21.1


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

USNO-B.1_id  R2
1105-0415742 17.60
1105-0415769 17.54
1105-0415805 16.38
1106-0408959 17.07
1105-0415666 16.91