GCN Circular 7040

Dirk Grupe (PSU) and Patricia Schady (MSSL/UCL) report on behalf of the 
Swift
team:

The Swift XRT began observing the field of GRB 071028B (GCN 7019
Not found
 
 
; Cummings
2007) on 2007 October 30 13:36 UT approximately 212 ks after the burst.
 Note that this burst was discovered in ground  processing of the BAT data.
 Therefore no immediate
observations after the burst were performed. There are clearly three sources
within the 3' BAT error circle. The brightest of these (0.01 counts/s)
coincides with a known source listed in the USNO catalogue.
There is one source nearly at the center of the BAT error circle at RA-2000,
Dec-2000 354.16300, -31.62050 which corresponds to

RA-2000 = 23 36 39.1
Dec-2000 = -31 37 13.8

with a 4.8" XRT error circle. The second source is located at
354.11579, -31.63948 corresponding to

RA-2000: 23 36 27.8
Dec-2000: -31 38 22.1
with a 4.8" XRT error circle.

UVOT observed the field of GRB 071028B for a total of 6443s in the 
V-filter.
There is no optical counterpart within the XRT error circles of the 
first and
second source. The
3-sigma upper limits are  V > 21.3mag and V >21.6 mag, respectively.
These values are not corrected for the expected
Galactic extinction corresponding to a reddening of E(B-V) = 0.02 mag in 
the
direction of the burst (Schlegel et al. 1998). There are no counterparts at
either of the  source positions in the USNO catalogue within the XRT error
radius (90% containment).


This circular is an official product of the Swift team