GCN Circular 13909
Subject
GRB 121025A: Swift-XRT observation
Date
2012-10-27T10:34:49Z (12 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
K.L. Page, R.L.C. Starling and P.A. Evans (U. Leicester) report on behalf
of the Swift-XRT team:
Swift performed a Target of Opportunity observation of the MAXI-detected
GRB 121025A (Asada et al., GCN Circ. 13895), starting 26.1 ks after the
trigger. A series of four tiled pointings was performed, in order to cover
the MAXI error circle. Within these fields, one > 3 sigma uncatalogued
source was detected, at RA, Dec = 248.38182, 27.67189, which is equivalent
to:
RA(J2000) = 16h 33m 31.64s
Dec(J2000) = 27d 40' 18.8"
with an uncertainty of 3.8 arcsec (radius, 90% containment). This source
has a mean count rate of 0.022 +/- 0.004 count s^-1. A spectrum formed
from the 1.8 ks of data can be fitted with an absorbed power-law with a
photon spectral index of 2.36 (+0.57,-0.56). The best-fitting absorption
column is consistent with the Galactic value of 3.8 x 10^20 cm^-2
(Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV
flux conversion factor deduced from this spectrum is 3.7 x 10^-11 (4.5 x
10^-11) erg cm^-2 count^-1.
It is not possible to determine whether this source is fading at this
time and, therefore, whether it is the X-ray afterglow.
This circular is an official product of the Swift-XRT team.