GCN Circular 4978

Subject

GRB060418: Swift/UVOT Observations

Event

Date

2006-04-18T20:46:46Z (20 years ago)

From

Patricia Schady at MSSL/Swift <ps@mssl.ucl.ac.uk>

P. Schady (UCL-MSSL), A. D. Falcone (PSU), report on behalf of the Swift/UVOT 
team:

The Swift/UVOT began taking data on the field of GRB060418 at 
2006-04-18T03:07:36, 88 s after the BAT trigger (Falcone et al., GCN 4966Loading...
 
 ). The 
source is observed to decay in six of the UVOT filters, but was not detected in 
the UVW2 filter down to a 3-sigma limiting magnitude of UVW2 > 20.4 in a 949s 
coadded image. This is consistent with the reported redshift of z=1.49 (Dupree 
et al. 2006; GCN 4969Loading...
 
 ). The magnitudes for the filters in which there was a 
detection are as follows:

Filter  T_mid(s)  Exp(s) Mag

V       393        393   14.99 +/- 0.02
         5996       197   18.84 +/- 0.33
B       675        10    16.22 +/- 0.13
         10765      295   19.87 +/- 0.27
U       656        20    15.83 +/- 0.09
         6610       197   18.55 +/- 0.20
UVW1    632        20    16.47 +/- 0.19
         6405       197   19.04 +/- 0.40
UVM2    608        20    17.30 +/- 0.30
         4343       197   > 19.30
White   137        10    14.32 +/- 0.03
         11676      295   19.23 +/- 0.16

These magnitudes are uncorrected for the estimated Galactic
reddening of E_{B-V} = 0.224 mag (Schlegel et al. 1998).