[vsnet-grb-info 4960] GRB 070724B: Swift/UVOT Upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6677
SUBJECT: GRB 070724B: Swift/UVOT Upper limits
DATE:    07/07/28 15:46:01 GMT
FROM:    Margaret Chester at PSU  <chester at astro.psu.edu>

M.M. Chester (PSU) and P. Romano (Uni-Bicocca and OAB) report on behalf
of the Swift UVOT team:

The Swift/UVOT observed the field of GRB 070724B (detected by
SuperAGILE; Feroci et al., GCN Circ. 6668) beginning 2007-07-27 00:02:11
UT, 48.6 hours after the burst trigger time.

We do not find any new source in any of the UVOT observations inside the
refined Swift/XRT error circle for the likely candidate, source #1
(RA,DEC(J2000)= 17.48497, 57.67616, Romano et al., GCN Circ. 6675).  We
note a cataloged star, V=18.2, 7.6 arcsec from the XRT position.

The 3-sigma upper limits for detecting a source inside the XRT error
circle in the co-added frames are:

Filter   Tstart   Tstop    Exp     Magnitude
            (s)     (s)     (s)    (3-sigma UL)
White    179270  197091   1776       21.3
v        175022  196602   2023       19.8

The values quoted above are not corrected for the expected Galactic
extinction corresponding to a reddening of E_{B-V} = 0.51 mag in the
direction of the burst (Schlegel et al. 1998).