GCN Circular 3026

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

The Swift Ultra-Violet/Optical Telescope (UVOT) began observations of 
GRB050215b (GCN 3024
Not found
 
 
) on February 15, 2005 at 02:35:10 UT.  We detect no 
source down to a magnitude of 19.5 in the V-filter for a 100 second 
exposure 1747s after the BAT trigger.  No source was detected in the other 
UVOT filters.  The limiting magnitudes in each of the UVOT filters are as 
follows:

  UVW2 = No source identified down to 19.2 (3-sigma) for a 10 second 
exposure @ 88 seconds after the burst
  UVM2 = No source identified down to 21.3 (3-sigma) for a 100 second 
exposure @ 1853 seconds after the burst
  UVW1 = No source identified down to 20.2 (3-sigma) for a 100 second 
exposure @ 1959 seconds after the burst
  U = No source identified down to 19.8 (3-sigma) for a 100 second exposure 
@ 2065 seconds after the burst
  B = No source identified down to 19.9 (3-sigma) for a 100 second exposure 
@ 2171 seconds after the burst
  V = No source identified down to 19.5 (3-sigma) for a 100 second exposure 
@ 1747 seconds after the burst

We caution that the instrument is not yet fully calibrated and that the 
magnitude limits presented here may need to be refined at a future date.