[vsnet-grb-info 13874] GRB 130831A: ISON-Kislovodsk optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15188
SUBJECT: GRB 130831A: ISON-Kislovodsk optical observations
DATE:    13/09/07 23:52:12 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

A. Volnova (IKI),  V. Linkov (ISON), K. Polyakov (ISON), D. Ivanov 
(ISON), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of 
larger GRB follow-up collaboration:

We observed the afterglow (Hagen et al., GCN  15139; Guidorzi et al., 
GCN 15140) of the Swift GRB 130831A (Hagen et al., GCN  15139) with 
SANTEL-400AN  telescope of ISON-Kislovodsk observatory  starting on 
Aug. 31  (UT) 19:12:30.  We took several unfiltered  images. Preliminary 
photometry of combined images is following

T_start              T0+       Filter, Exposure, OT,    OT_err
(UT)                 (mid, d)            (s)

2013-08-31T19:12:30  0.26113   none    840       18.32  0.08
2013-08-31T19:28:20  0.27212   none    840       18.44  0.10
2013-08-31T19:47:24  0.29470   none    1760      18.47  0.13

The photometry is based on reference stars SDSS-DR9, (R mag, 
transformation by Lupton 2005)

N	SDSS id			R(Lupton)errR
1	J235443.71+292539.3	13.491	 0.016
2	J235438.60+292547.3	14.136	 0.015
3	J235423.64+292452.8	17.120	 0.016