[vsnet-grb-info 1900] GRB 050802: Swift/UVOT observations

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3739
SUBJECT: GRB 050802: Swift/UVOT observations
DATE:    05/08/02 17:34:24 GMT
FROM:    Katie McGowan at MSSL-UCL  <km2 at mssl.ucl.ac.uk>

K. McGowan (MSSL), D. Band (GSFC-UMBC), P. Brown,
C. Gronwall (PSU), H. Huckle, B. Hancock (MSSL)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began observing the afterglow of
GRB 050802 at 2005-08-02T10:15:14, 286 s after the
BAT trigger (Band et al., GCN 3734).  We detect the
afterglow in the V-band data at a position (J2000,
corrected to the DSS coordinates) of:

RA   14:37:5.69 (+/- 1 arcsec)
Dec +27:47:12.2 (+/- 1 arcsec)

The data are extracted using a 6 arcsec radius aperture
centered on the source position.  If the significance of
the source detection was less than 2 sigma we determined a
3-sigma limiting magnitude.

Filter   Exposure (s)  T_mid (s)   Magnitude      Notes

V        100           336         17.07+/-0.09   detection
V        10            466         17.32+/-0.20   detection
V        10            550         17.10          3-sig limit
V        10            634         17.17          3-sig limit
V        10            718.5       16.77+/-0.20   detection
V        10            803         17.34          3-sig limit
V        10            887.5       17.04+/-0.20   detection
V        10            972         17.46          3-sig limit
V        100           1463        18.35+/-0.09   detection
V        100           2088        18.81+/-0.09   detection

where T_mid is the midpoint of the exposure post-trigger in seconds.

Analysis of the data from the other filters is ongoing.

The magnitudes are based on preliminary zero points, measured in
orbit, and will require refinement with further calibration.