TITLE:   GCN CIRCULAR
NUMBER:  41783
SUBJECT: GRB 250911A: Swift-XRT observations
DATE:    25/09/11 05:16:58 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

M. Perri (SSDC & INAF-OAR), P.A. Evans (U. Leicester) and J.A. Kennea
(PSU) report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 250911A at 02:25:07.6 UT,
3441.5 seconds after the BAT trigger. Using promptly downlinked data we
find a fading, uncatalogued X-ray source located at RA, Dec 263.75102,
-16.85448 which is equivalent to:
   RA(J2000)  = 17h 35m 00.24s
   Dec(J2000) = -16d 51' 16.1"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 53 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 https://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 (3.44 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 4.3
(+3.44/-2.88) x 10^21 cm^-2 (90% confidence).