TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4210
SUBJECT: GRB051105B: Swift/XRT upper limit
DATE:    05/11/08 10:33:57 GMT
FROM:    Gianpiero Tagliaferri at OAB-INAF  <taglia@merate.mi.astro.it>

T. Mineo (INAF-IASF PA), S. Campana (INAF-OAB),
G. Chincarini (INAF-OAB and UNIMIB), D. Malesani (SISSA),
A. Moretti (INAF-OAB), P. Romano (INAF-OAB),
G. Tagliaferri (INAF-OAB) on behalf of the Swift XRT team

The Swift/XRT  began observing the field of GRB 051105B
on 2005-11-07 at 16:41:31 UT, about 2.25 days after the
INTEGRAL trigger (GCN 4192; Mereghetti et al.). 
A weak X-ray source is detected at RA(2000)=00h 37m 53.7s'
Dec(2000)=-40d 29m 14s,  with an estimated uncertainty
of 7 arcsec (90% containment), including corrections
for the XRT boresight offset. This source is 3.7 arcsec away
from the bright star HD 3516, which we identify as the optical
counterpart.  No other X-ray source is detected within the BAT
error circle.  The 3 sigma upper limit is 1.1E-03 cts/s corresponding
to an unabsorbed 0.2-10 keV flux of 5E-14 erg cm^-2 s^-1, assuming
a power-law model with  an energy index slope of -1 and a
Galactic absorbing column  of 3.0E20 cm^-2.