[vsnet-grb-info 6209] GRB 080605: Swift-XRT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7838
SUBJECT: GRB 080605: Swift-XRT refined analysis
DATE:    08/06/06 17:22:59 GMT
FROM:    Boris Sbarufatti at INAF-IASF-Pa  <sbarufatti at ifc.inaf.it>

B. Sbarufatti, V. Mangano, V. La Parola (INAF-IASF Pa) report on
behalf of the Swift-XRT team

The XRT began observations of GRB 080605 (trigger=313299,
Sbarufatti et al., GCN circ. 7828) started on 2008 May 05 at 23:49:36 UT,
97 s after the BAT trigger. The data consist of 642 s in Windowed Timing
mode and 4.3 ks s in Photon Counting mode.

The light curve is described by a powerlaw with initial slope
0.65 (+/-0.05) until T+ 280s (+90, - 45), at which point the decay
steepens to an index 1.32 (+/-0.03).

The spectrum of the WT mode data can be fitted by a powerlaw with
photon index 1.78 (+/- 0.04) and an intrinsic absorbing column of
6.6 (+/-0.9)E21 cm^-2 at z=1.6398 (Jakobsson et al., GCN circ. 7832),
in excess over the Galactic value of 6.67E20 cm^-2.
The observed (unabsorbed) flux is 7.5 (8.1)E-10 erg cm^-2 s^-1.
The first orbit PC mode spectrum  (379 s of exposure) can be
fit by a powerlaw with photon index 1.6 (+/- 0.2) and an
intrinsic absorbing column of 4.8 (+/-4)E21 cm^-2. The observed
(unabsorbed) flux is 3.0 (3.3)E-10 erg cm^-2 s^-1.

The countrate to flux conversion factor is 4.87e-11 erg cm^-2 s^-1.
The predicted countrate 24 h after the trigger is 1.6E-2 counts/s,
equivalent to an observed flux of 7.8E-13 erg cm^-2 cts^-1.

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