[vsnet-grb-info 4358] GRB070224: Swift-XRT Refined Analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6143
SUBJECT: GRB070224: Swift-XRT Refined Analysis
DATE:    07/02/25 05:11:37 GMT
FROM:    Judith Racusin at PSU  <racusin at 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.