GCN Circular 3050
Subject
GRB050219b: No Swift UVOT Detection of Afterglow Emission
Date
2005-02-20T19:06:55Z (20 years ago)
From
Patricia Schady at MSSL/Swift <ps@mssl.ucl.ac.uk>
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), M. Ivanushkina (PSU),
T. Kennedy, P. Smith, B. Hancock (MSSL), S. Koch (PSU), M. Carter, H.
Huckle (MSSL), P. Broos, 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:
A re-examination of the UVOT data at the new XRT position (Racusin et al,
GCN 3049) revealed no new source detection down to the following 3-sigma
limiting magnitudes
Filter Lim_Mag Duration T_start
UVW2 ~ 22.16 1154 T+3120
UVM2 ~ 22.24 1435 T+3243
UVW1 ~ 22.23 940 T+3349
U ~ 20.74 100 T+3455
B ~ 20.9 100 T+3561
V ~ 19.41 100 T+3136
Several exposures were taken in the UV filters, and these were co-added in
order to derive the limiting magnitudes. This is the cause of the apparent
overlap between the duration of these exposure and the start time of the
exposures in the optical filters.
We caution that the instrument is not yet fully calibrated and that the
magnitude limits presented here may need to be refined.