[vsnet-grb-info 18563] GRB 161004A: refined analysis of TSHAO optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20011
SUBJECT: GRB 161004A: refined analysis of TSHAO optical observations
DATE:    16/10/07 23:58:37 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

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

We present a refined analysis of our observations (Mazaeva et al., GCN 
19980) of  the field of GRB 161004A  (Evans  et al., GCN 19979)  with 
Zeiss-1000 (East) 1-m telescope of Tien Shan Astronomical Observatory. 
We obtained several images in R filter starting on Oct. 04 (UT) 
13:36:52.  In a combined image of the first 30 minutes of our 
observations we detect the afterglow (Breeveld et al., GCN 19984). 
Preliminary photometry of a combined image is following

Date       UT start   t-T0   Filter   Exp.  OT     Err.  UL
                       (mid, days)     (s)
2016-10-04 13:36:52 0.03632  R       9*180  21.65  0.25  21.7

Photometry is based on nearby SDSS-DR9 stars used in GCN 19980.