[vsnet-grb-info 11641] GRB 120311A: Swift-XRT observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13034
SUBJECT: GRB 120311A: Swift-XRT observations
DATE:    12/03/11 07:29:52 GMT
FROM:    Phil Evans at U of Leicester  <pae9 at star.le.ac.uk>

P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), D.N. Burrows
(PSU), J.A. Kennea (PSU), M. Perri (ASDC) and G. Tagliaferri (INAF-OAB)
report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 120311A at 06:26:19.9 UT,
3161.6 seconds after the BAT trigger. Using promptly downlinked data we
find an uncatalogued X-ray source located at RA, Dec 273.08966,
14.29709 which is equivalent to:
   RA(J2000)  = 18h 12m 21.52s
   Dec(J2000) = +14d 17' 49.5"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 80 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (1.03 x
10^21 cm^-2, Kalberla et al. 2005), with an excess column of 2.5
(+2.12/-1.86) x 10^21 cm^-2 (90% confidence).