GCN Circular 3317
Subject
GRB 050422: Swift-UVOT observation
Date
2005-04-22T18:59:05Z (19 years ago)
From
Katie McGowan at MSSL-UCL <km2@mssl.ucl.ac.uk>
K. McGowan (MSSL), A. Blustin (MSSL), S. Rosen (MSSL),
L. Barbier (GSFC), S. Hunsberger (PSU), M. Still (GSFC),
P. Smith (MSSL), N. Gehrels (GSFC), K. Mason (MSSL),
J. Nousek (PSU), on behalf of the Swift UVOT team
Starting with the data taken ~113s after the BAT trigger
(Barbier et al, GCN 3314) we have co-added the data of
GRB 050422 in each of the Ultra-Violet/Optical Telescope
(UVOT) V, B and U bands. The co-added image for the V-band
is made up of 1 x 100 s and 5 x 10 s exposures, the co-added
B-band and U-band images are made up of 5 x 10 s exposures.
The XRT error circle (Pagani et al., GCN 3315) falls
partially on a known source from the DSS. No new source
is detected in any of the bands; we estimate the five
sigma magnitude upper limits from the co-added images to be:
Filter Upper Limit Duration(s) T_start(s) T_mid(s)
V 17.9 148.7 112.9 374.1
B 18.2 48.8 258.6 432.5
U 17.8 48.8 244.5 418.0
Where T_start is time after trigger, and T_mid is the midpoint
of the summed exposure.
The magnitudes are based on preliminary zero-points, measured
in orbit, and will require refinement with further calibration.
We note that the reddening in this direction is E_{B-V} = 1.4.