[vsnet-grb-info 4867] Swift/UVOT Observations of GRB070704

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6597
SUBJECT: Swift/UVOT Observations of GRB070704
DATE:    07/07/05 10:16:46 GMT
FROM:    Patricia Schady at MSSL/Swift  <ps at mssl.ucl.ac.uk>

P. Schady (MSSL-UCL) and T. Sakamoto (NASA/ORAU) report on the behalf of the 
Swift UVOT team:

The Swift/UVOT observed the field of GRB 070704 starting 142 s after the 
BAT trigger (Sakamoto et al. 2007, GCN Circ. 6594).  We do not find any 
source, in any of the UVOT observations, inside the XRT error circle 
(Sakamoto et al. 2007, GCN Circ. 6594).

The 3-sigma upper limits for detecting a source inside the refined XRT 
error circle in the initial data products are:

Filter    T_mid(s) Exp(s) Mag (3-sigma upper limit)
-------------------------------------------------------
V         654      597    19.16
B         749      10     17.56
U         729      20     17.64
UVW1      5603     439    18.91
UVM2      4431     239    19.36
UVW2      5697     220    19.27
White     574      209    19.65
-----------------------------------------------------------------

where T_mid is the weighted mid time of the coadded exposure. The values 
quoted above are not corrected for the expected Galactic extinction 
corresponding to a reddening of E_{B-V} = 1.81 mag in the direction of the 
burst (Schlegel et al. 1998).