[vsnet-grb-info 16879] GRB 150817A: AAO optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18160
SUBJECT: GRB 150817A: AAO optical observations
DATE:    15/08/18 19:09:15 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

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

We observed the field of the Swift GRB 150817A (D’Elia et al., GCN 
18143) with AS-32 (0.7m) telescope of Abastumani Observatory starting on 
Aug. 17 (UT) 17:00:31.  Within the enhanced XRT error circle (Osborne et 
al., GCN 18146) we do not detect the optical afterglow (Butler et al., 
GCN 18145; Cenko et al., GCN 18153). In particular the  magnitude of the 
first object (Butler et al., GCN 18144) is 21.6 +/- 0.2.  Upper limit of 
the object is following

Date       UT start    t-T0     Filter  Exp.     UL(3 sigam)
                        (mid, days)      (s)

2015-08-17 17:00:31    0.64432  None    24*120   22.4

The photometry is based on nearby USNO-B1.0 stars
USNO-B.1_id  R2
0779-0405699 16.12
0779-0405721 16.40
0779-0405742 16.47
0779-0405723 16.94
0779-0405664 17.60