[vsnet-grb-info 16809] GRB 150728A: FTN observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18090
SUBJECT: GRB 150728A: FTN observations
DATE:    15/07/28 17:07:38 GMT
FROM:    Simone Dichiara at Ferrara U/Italy  <dichiara at fe.infn.it>

S. Dichiara, C. Guidorzi (U. Ferrara), C.G. Mundell (U. Bath),
S. Kobayashi (LJMU), A. Gomboc (U. Ljubljana) on behalf of
a large collaboration report:

The 2-m Faulkes Telescope North began observing Swift GRB 150728A
(Krimm et al. GCN 18087) on July 28, 13:48:25 UT (~57 minutes after
the BAT trigger) with SDSS r and i filters.

we identify an uncatalogued object within XRT error circle
(Beardmore et al. GCN 18088), at the following position:

RA(J2000) = 19:28:54.81
Dec(J2000)= +33:54:58.0

with an uncertainty of 1". The counterpart has the following
 magnitudes:

Mid time from  Total Exp   Filter    Magnitude
trigger (min)   (s)
-------------------------------------------------
61.8            120x5        r'     21.8 +- 0.3
73.3            120x5        i'     20.7 +- 0.3
-------------------------------------------------

Magnitudes are calibrated against nearby USNOB-1 stars
(R2 and I).
Presently we cannot state anything about possible variability in
the source flux. However, we note that field is quite crowded.