[vsnet-grb-info 5132] GRB 071001: Swift-XRT Team refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6835
SUBJECT: GRB 071001: Swift-XRT Team refined analysis 
DATE:    07/10/02 00:32:22 GMT
FROM:    Kim Page at U.of Leicester  <kpa at star.le.ac.uk>

K.L. Page, A.P. Beardmore (U. Leicester) and M. De Pasquale (UCL-MSSL) 
report on behalf of the Swift-XRT team:

We have analysed the two orbits of Swift-XRT data obtained for GRB 071001 
(De Pasquale et al., GCN Circ. 6832), totalling 37 seconds of Windowed 
Timing (WT) data and 1.3 ks of Photon Counting mode data. Because of a 
temporary problem with the star trackers, we use only the data when the 
attitude can be said to be stable to find a refined position of RA, Dec = 
149.7336, -59.7818, which is equivalent to:

RA(J2000):   09 58 56.07
Dec(J2000): -59 46 54.5

with an estimated uncertainty of 6 arcsec (radius, 90% containment 
including boresight uncertainty). This is 83 arcsec from the 
ground-calculated BAT position (Stamatikos et al., GCN Circ. 6834) and 6.2 
arcsec from the initial XRT position quoted in GCN Circ. 6832.

The X-ray light-curve shows an initial steep decay, with alpha = 
3.0 +/- 0.2, breaking at about 310 seconds after the trigger to a flatter 
slope of 0.2 +/- 0.1.

The WT spectrum (89-120 seconds after the trigger) can be modelled by a 
power-law of Gamma = 2.2 +0.5/-0.4, absorbed by the Galactic column in 
this direction of 7.6e21 cm^-2. The 0.3-10 keV observed (unabsorbed) flux 
during this time is 4.2e-10 (2.0e-9) erg cm^-2 s^-1.

With only 2 orbits of data, predicting the count rate at 24 hours would 
not lead to an accurate result. No further Swift observations of this 
burst are planned.

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