[vsnet-grb-info 1735] GRB050712: UVOT candidate optical counterpart

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3575
SUBJECT: GRB050712: UVOT candidate optical counterpart
DATE:    05/07/12 19:44:20 GMT
FROM:    Evert Rol at U.Leicester  <er45 at star.le.ac.uk>

E. Rol (U. Leicester), T. Poole, K. McGowan (MSSL), D. Grupe,
J. Nousek (PSU), W. Voges (MPE), and N. Gehrels (GSFC) report on behalf
of the Swift UVOT team:

Analysis of the quick-look data from the UVOT for GRB050712 (Grupe et
al., GCN 3573) reveals a single, relatively bright source inside the
XRT error circle (Falcone et al., GCN 3574) which is not visible in
the DSS red and blue surveys. Its position is (J2000):

  RA   5:10:48.1
  Dec 64:54:47.6

with the astrometry calibrated to the 2MASS catalogue.

An initial estimate of the V-band magnitude for the source over the
timespan of 164-264 seconds after the trigger is V = 18.02 +/- 0.29.
Further analysis is underway to investigate the variability of the
source.

We note that the early UVOT findingchart ('genie image') was not
centred at BAT position, which resulted in the candidate XRT/UVOT
position being outside the field of view of the findingchart.