GCN Circular 7054
Subject
Swift/UVOT initial analysis of GRB071109
Event
Date
2007-11-11T01:41:58Z (18 years ago)
From
Paul Kuin at MSSL <npkuin@googlemail.com>
N.P.M. Kuin (MSSL/UCL) and M. Perri (ASDC) report on behalf of the
Swift-UVOT team:
The Swift/UVOT observed the INTEGRAL burst GRB 071109 (Mereghetti
et al. GCN Circ. 7046) starting at 22:21 UT, 105 minutes after the
trigger, cycling through exposures in the the uvw1, u, b, uvw2, v
and uvm2 filters. No afterglow is detected at the position of the VLA
measurement (Chandra et al. GCN Circ. 7049). A possible source at
position RA=19:19:42.303,DEC=+02:01:21.14(J2000) was investigated,
since it was detected at the 3-sigma level (u=20.9+/-0.6 mag) in
the coadded U-filter images. This source is considered spurious
since it was not found in any of the other filters, taken before
or after the U-filter exposures.
No other fading source is found within the INTEGRAL error circle
in this is a crowded field.
The following 3-sigma upper limits were determined at the position
of the VLA detection (RA=19:19:51.67,DEC=+02:01:49.88):
Filter Tstart(s) Tstop(s) Exp(s) Mag (3-sigma Upper Limits)
uvw1 6350 24158 1678 > 21.47
u 6782 24373 835 > 21.17
b 7000 24588 835 > 21.56
uvw2 7220 25435 3346 > 22.25
v 8078 25651 835 > 20.58
uvm2 8300 26033 2189 > 21.73
The values quoted above are not corrected for the expected Galactic
extinction corresponding to a reddening of E_{B-V} = 0.61 mag in the
direction of the burst (Schlegel et al. 1998).