TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3095
SUBJECT: GRB 050315: Early Observations with Swift/UVOT
DATE:    05/03/15 23:42:15 GMT
FROM:    Stephen Holland at USRA/NASA/GSFC/SSC  <sholland@milkyway.gsfc.nasa.gov>

S. Rosen, K. McGowan, M. De Pasquale (MSSL), P. Boyd (GSFC/UMBC),
S. T.  Holland, M. Still (GSFC/USRA), W. Landsman (GSFC),
S. Hunsberger (PSU), A.  Breeveld (MSSL), P. Roming (PSU), K. Mason,
P. Schady (MSSL), M.  Ivanushkina (PSU), T. Poole (MSSL), C. Gronwall
(PSU), A. Blustin (MSSL), P. Brown, S. Koch (PSU), M. Carter,
H. Huckle (MSSL), P. Broos (PSU), T.  Kennedy, P. Smith, B. Hancock
(MSSL), A. Parsons (GSFC), J. Nousek (PSU), N. Gehrels (GSFC), on
behalf of the Swift UVOT team.

     The Swift Ultra-Violet/Optical Telescope (UVOT) began observing
the field of GRB 050315 (GCN 3094) at 21:01:13 UT, approximately 90
seconds after the BAT trigger.  The first image was sent down via the
TDRSS link approximately 200 seconds after the trigger.  This image
was a 100 second exposure taken with the V filter.  It was centred on
the BAT position, and had a size of 5 x 5 arcminutes, which covered
88% of the BAT error circle.  The middle of the exposure was 140.19
seconds after the BAT trigger.  The image was binned 8 x 8 to reduce
the bandwidth required for transmission.  A comparison against the DSS
showed no new sources down to a 5-sigma limiting magnitude of
approximately V = 18.5.  We stress that this limiting magnitude is
based on ground calibrations and may be uncertain by approximately 0.5
mag.  The full-resolution version of this image will be transmitted to
the ground during the next Malindi pass, which will occur at
approximately 0000 UTC March 16, 2005.