GCN Circular 6143
Subject
GRB070224: Swift-XRT Refined Analysis
Event
Date
2007-02-25T05:11:37Z (20 years ago)
From
Judith Racusin at PSU <racusin@astro.psu.edu>
J. Racusin, J. Kennea, D. Morris, C. Pagani, L. Vetere (PSU) report on
behalf of the Swift-XRT team:
We have analysed the first 3 orbits of Swift-XRT data available for GRB
070224 (Racusin et al., GCN 6137), consisting of 45 s of Windowed Timing
(WT) mode data, and ~1.7 ks of Photon Counting (PC) mode data. The
refined XRT position from the PC data is RA,Dec= 179.02684, -13.3304 which
is:
RA(J2000) = 11h 56m 06.44s
Dec(J2000) = -13d 19' 49.5"
with an uncertainty of 3.8 arcsec (90% containment). This is 5.0
arcseconds from the initial position reported in GCN 6137, and 134
arcseconds from the BAT refined position (Tueller et al., GCN 6141).
The preliminary 0.3-10.0 keV lightcurve shows a steep fading behavior in
the first orbit with a decay index of 3.1 +/- 0.2. The data in the
subsequent orbits provides only an upper limit. It is not currently
possible to determine if there has been a break to a flatter decay.
The WT spectrum is fit by an absorbed power-law with a photon index of 2.8
+/- 0.6. The absorption is at a level of 6.0e20 cm^-2, consistent with
Galactic absorption along the line of sight (4.1e20 cm^-2). The average
0.3-10 keV unabsorbed flux of the WT spectrum is 2.1e-10 ergs cm^-2 s^-1.
This circular is an official product of the Swift-XRT team.