[vsnet-grb-info 12278] GRB 120817A: Swift-XRT observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13662
SUBJECT: GRB 120817A: Swift-XRT observations
DATE:    12/08/17 08:45:10 GMT
FROM:    Phil Evans at U of Leicester  <pae9 at star.le.ac.uk>

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

The XRT began observing the field of GRB 120817A at 07:41:33.5 UT,
3110.8 seconds after the BAT trigger. Using promptly downlinked data we
find an uncatalogued X-ray source located at RA, Dec 250.69098,
-38.35404 which is equivalent to:
   RA(J2000)  = 16h 42m 45.84s
   Dec(J2000) = -38d 21' 14.5"
with an uncertainty of 4.2 arcseconds (radius, 90% containment). This
location is 65 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.  We
cannot determine whether the source is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 2.88
x 10^21 cm^-2 (Kalberla et al. 2005).