[vsnet-grb-info 16813] GRB 150728A: AAO optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18094
SUBJECT: GRB 150728A: AAO optical observations
DATE:    15/07/29 18:30:31 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

E. Mazaeva (IKI), R. Inasaridze (AAO), Sh. Makandarashvili (AAO),   A.
Volnova (IKI), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of 
larger GRB follow-up collaboration:

We observed the field of the Swift GRB 150728A (Krimm et al. GCN 18087) 
  with AS-32 (0.7m) telescope of Abastumani Observatory starting on Jul. 
28 (UT) 19:32:14.  Within the enhanced XRT error circle (Beardmore et 
al. GCN 18088) we detected the object coinciding with the object found 
by FTN (Dichiara et al. GCN 18090).  A photometry of the object is following

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

2015-07-28 19:32:14    0.30491  None    28*120   20.6+/-0.25

The photometry is based on nearby USNO-B1.0 stars
USNO-B.1_id  R2
1239-0338943 17.06
1239-0338998 16.69

The photometry could be biased by nearby star. Presently we cannot say 
nothing about variability of the object and more observation is 
necessary to confirm/reject the object as afterglow of GRB 150728A.