[vsnet-grb-info 1792] GRB 050716 - UKIRT identification of candidate afterglow

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3632
SUBJECT: GRB 050716 - UKIRT identification of candidate afterglow
DATE:    05/07/17 00:35:30 GMT
FROM:    Nial Tanvir at IofA U.Cambridge  <nrt at ast.cam.ac.uk>

N. Tanvir, K. Lowe, T. Gledhill (U. of Hertfordshire), A. Levan,
E. Rol, P. O'Brien, N. Bannister (U. of Leicester), T. Carroll (JACH),
C. Guidorzi, A. Gomboc, A. Monfardini, I. Steele, C. Mundell,
C. Mottram, M. Bode R. Smith, D. Carter (Liverpool JMU) report:

We imaged the Swift/XRT error circle of GRB 050716 (GCN 3623/3624)
with UKIRT/UFTI starting about 56 minutes post-burst.

Just outside the XRT error circle we find a fading point source
at position (astrometry relative to nearby 2MASS star):

   22 34 20.73   +38 41 03.6  (J2000)

Provisional photometry indicates that this source declines from K~17.8
to K~18.3 between two integrations separated by about 30 mins, making it
very likely to be the afterglow of GRB 050716.

Interestingly, it also appears to be red with J-K~2.5.  A reanalysis
of the very early FT-N data (GCN 3625), however, shows excess flux in
R and I at the source position which, although not a clear detection
(due to the faintness and proximity of nearby USNO star), suggests
that the source is probably reddened rather than at very high
redshift.

Images can be found at:

  http://star-www.herts.ac.uk/~nrt/050716.html

Further observations are planned.
This message may be cited.