GCN Circular 3046
Subject
GRB050219b: No Swift UVOT Detection of Afterglow Emission
Date
2005-02-20T04:45:45Z (20 years ago)
From
Patricia Schady at MSSL/Swift <ps@mssl.ucl.ac.uk>
M. Ivanushkina (PSU), T. Poole (MSSL), C. Gronwall (PSU), A. Blustin
(MSSL), P. Brown (PSU), 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), P. Roming (PSU), K. Mason, P. Schady
(MSSL) P. Broos (PSU), T. Kennedy, P. Smith, B. Hancock (MSSL), S. Koch
(PSU), M. Carter, H. Huckle (MSSL), J. Racusin (PSU), E. Fenimore (LANL),
B. Zhang (UNLV), J. Nousek (PSU), N. Gehrels (GSFC), on behalf of the
Swift UVOT team.
The Swift Ultra-Violet/Optical Telescope (UVOT) began observations of
GRB050219b on February 19, 2005, at 12:57:51 UT, 52 minutes after the
initial Swift BAT trigger (Cummings et al, GCN 3044). The delay in
observations was due to the Earth-limb constraint, which prevented an
immediate slew. We detect no source at the Swift XRT position (Burrows et
al, GCN 3043). The limiting magnitudes (3-sigma) in each of the UVOT
filters are as follows:
Filter Lim_Mag Duration T_start
UVW2 ~ 22.04 1154 T+3120
UVM2 ~ 20.95 100 T+3243
UVW1 ~ 20.65 100 T+3349
U ~ 20.92 100 T+3455
B ~ 20.85 100 T+3561
V ~ 19.38 100 T+3136
The limiting magnitude for the UVW2 filter was calculated from a summation
of four separate exposures taken at different times between observations
made in other filters. This is the cause of the overlap between the
duration of the UVW2 exposure and the start of some of the other
exposures.
We caution that the instrument is not yet fully calibrated and that the
magnitude limits presented here may need to be refined.