[vsnet-grb-info 2463] GRB 051117A: Swift/UVOT Detection of an Afterglow

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4300
SUBJECT: GRB 051117A: Swift/UVOT Detection of an Afterglow
DATE:    05/11/22 19:02:07 GMT
FROM:    Stephen Holland at USRA/NASA/GSFC/SSC  <sholland at milkyway.gsfc.nasa.gov>

GRB 051117A: Swift/UVOT Detection of an Afterglow

S. T. Holland (GSFC/USRA), D. Band (GSFC), K. Mason (PPARC),
F. Marshall (GSFC), & N. Gehrels (GSFC) on behalf of
the Swift/UVOT team report:

       The Swift/UVOT began observing the field of GRB 051117A (BAT
Trigger 163268; Band et al. 2005, GCN Circular 4280) at
2005-11-17T10:53:10, 111 seconds after the burst.

       We detect a fading source corresponding to the UVOT source
in Band et al. (2005, GCN Circular 4280).  The refined coordinates
of this source are:

RA(J2000) =  15:13:39.09
Dec(J2000) = +30:52:12.7

with a positional uncertainty of +/-0.5 arcsec (1-sigma).  The
transient has V = 20.01 +/- 0.46 (1-sigma, statistical) in a 200 s
exposure starting at 110 seconds after the BAT trigger.  This value
supersedes the approximate magnitude given in Band, et al. (2005, GCN
Circular 4280).  This magnitude has not been corrected for Galactic
extinction.

      The magnitude in the UVOT White filter is 19.19 +/- 0.16
(1-sigma, statistical) in a 50 s, exposure starting 531 s after the
BAT trigger.  The source has faded to a White magnitude of
approximately 21.5 by 3.5 days after the burst.  There is weak
evidence that the source is extended, so this may represent the
luminosity of the host galaxy of GRB 051117A.