TITLE:   GCN CIRCULAR
NUMBER:  18311
SUBJECT: GRB 150907A: Swift-XRT afterglow detection
DATE:    15/09/14 16:02:36 GMT
FROM:    Boris Sbarufatti at INAF-OAB/IASFPA  <boris.sbarufatti@brera.inaf.it>

J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), A. D'ai (INAF-IASFPA), A. Maselli
 (INAF-IASFPA), A. Melandri (INAF-OAB), D.N. Burrows (PSU) and P.A.
Evans (U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has conducted further observations of the field of the
MAXI-detected burst GRB 150907A (Nakagawa et al. GCN Circ. 18246). The
observations now extend from T0+8.8 ks to T0+489.4 ks. The source
previously reported by Kennea et al. (GCN Circ. 18250), "Source 1", is
fading with 3-sigma significance, and is therefore likely the GRB
afterglow.  The position of this source is RA, Dec=225.0528, -47.7080
which is equivalent to:

RA (J2000): 15:00:12.68
Dec(J2000): -47:42:28.8

with an uncertainty of 6.8 arcsec (radius, 90% confidence).  This
position is 10.9 arcmin from the MAXI position.  The source is fading
with alpha >0.5.

The results of the XRT-team automatic analysis of the likely afterglow
are at http://www.swift.ac.uk/xrt_products/TILED_GRB00048/index_1.php.
The results of the full analysis of the tiled XRT observations are
available at http://www.swift.ac.uk/xrt_products/TILED_GRB00048.

This circular is an official product of the Swift-XRT team.