GCN Circular 6258
Subject
GRB070406: Swift UVOT observations
Date
2007-04-08T00:33:09Z (17 years ago)
From
Wayne Landsman at GSFC/SSAI <landsman@milkyway.gsfc.nasa.gov>
W. Landsman (NASA/GSFC), M. Chester (PSU) and S. McBreen (MPE) report on
behalf of the Swift UVOT team:
Swift/UVOT observed the field of GRB 070406 starting 20.6 hours after
the trigger. Swift did not autonomously slew because the burst was
below the trigger threshold.
Comparison with pre-burst DSS and SDSS images show no new source within
the BAT error circle with the following 3 sigma upper limits in the
co-added frames in all filters:
Filter T_start T_Stop Exp(s) Mag 3-sig UL
(s) (s)
V 84712 132829 1407 21.6
B 74251 139272 3360 23.0
U 102871 138592 2539 22.4
UVW1 98648 137680 3666 24.3
UVM2 90394 133486 2845 23.5
UVW2 80549 131916 2626 23.9
White 75162 115280 1318 22.6
The blue galaxy found in pre-burst SDSS images (Kann, GCN 6256) within
the tentative XRT error circle (Troja et al., GCN 6255) is found from
the UVOT observations to be unusually bright in the UV filters.
Mag Err
V 20.05 0.15
B 20.06 0.05
U 19.11 0.04
UVW1 18.83 0.04
UVM2 18.52 0.05
UVW2 18.67 0.04
However, there is no compelling evidence of variability of this source
within the individual UVOT frames.