TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3475
SUBJECT: Swift/UVOT UV and optical detections of GRB 050525
DATE:    05/05/25 12:29:37 GMT
FROM:    Alexander Blustin at MSSL-UCL  <ajb@mssl.ucl.ac.uk>

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

Swift/UVOT has detected GRB 050525 in all of its UV and
optical filters. Using data from 65 seconds after the
burst, we obtain the following magnitudes from images
summed between the T_start and T_stop times in the table:

Filter    Magnitude     Exp (s)  T_start  T_stop

V       14.97 +/- 0.02   287      65       1292
B       16.53 +/- 0.03   188      224      1084
U       15.32 +/- 0.03   98       90       979
UVW1    15.63 +/- 0.04   98       196      2046
UVM2    15.75 +/- 0.06   98       182      952
UVW2    16.62 +/- 0.05   188      952      1189

Where T_start and T_stop are in seconds after the
trigger (Band et al. GCN 3466).

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