[vsnet-grb-info 14397] GRB 131231A: AAO optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15711
SUBJECT: GRB 131231A: AAO optical observations
DATE:    14/01/09 16:06:01 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

A. Volnova (IKI), R. Inasaridze (AAO), G. Inasaridze (AAO), V. 
Zhuzhunadze (AAO), Yu. Krugly (IA KhNU), I. Molotov (KIAM), A. Pozanenko 
(IKI) report on behalf of larger GRB follow-up collaboration:

We observed the optical counterpart of the Fermi/LAT GRB 131231A 
(Sonbas et al., GCN 15640; Xu et al. GCN 15641) with AS-32 (0.7m) 
telescope of Abastumani Observatory on Jan. 3, 4, and 5. We obtained 
several unfiltered images of 120 s exposure during each observational 
set. On stacked images we clearly detect the afterglow. The photometry 
based on the reference stars, R-mag, from Halpern (GCN 15646) is following:

Date        T_start   t-t0,     exp,    OT
              (UT)      mid, d    s

2014-01-03  17:08:16  3.54893  33x120  20.26 ± 0.06
2014-01-04  16:53:04  4.53207  29x120  20.32 ± 0.08
2014-01-05  15:59:46  5.50061  34x120  20.74 ± 0.13