[vsnet-grb-info 14172] GRB 131031A: Mondy optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15486
SUBJECT: GRB 131031A: Mondy optical observations
DATE:    13/11/15 00:06:28 GMT
FROM:    Alina Volnova at SAI MSU  <alinusss at gmail.com>

A. Volnova (IKI), E. Klunko (ISTP), M. Eselevich (ISTP), I. Korobtsev
(ISTP), A. Pozanenko (IKI) report on behalf of larger GRB follow-up
collaboration:

We observed the field of the Swift GRB 131031A (Cummings et al., GCN
15421) with AZT-33IK telescope of Sayan observatory (Mondy). We took
several images in R-filter of 60 s exposure on Nov., 01, 02, and 05.
In the stacked images from Nov. 01 and 02 in the XRT error circle
(Gompertz & Page, GCN 15424) we detected a source which is coincident
with the source reported by Gorosabel et al. (GCN 15426).

The details of the photometry are the following:

date         UT start  t-T0            Filter   Exp.    OT
                            (mid, days)             (s)
20131101 15:50:21 1.23918       R      147x60 22.23 +/- 0.14
20131102 14:59:29 2.17988       R      106x60 22.43 +/- 0.16
20131105 15:59:53 5.21974       R        91x60 >22.3 (UL 3 sigma)

The photometry is based 3 SDSS stars, R (gri -> R transformations by
Lupton 2005):

SDSS id                       R
J015828.04-013339.6  19.230
J015828.59-013429.3  17.299
J015835.16-013313.8  18.742