[vsnet-grb-info 9857] GRB 101008A: Swift-XRT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  11325
SUBJECT: GRB 101008A: Swift-XRT refined analysis
DATE:    10/10/09 08:36:00 GMT
FROM:    Claudio Pagani at U of Leicester  <cp232 at star.le.ac.uk>

C. Pagani (U. Leicester) and W. H. Baumgartner (GSFC/UMBC) report on
behalf of the Swift-XRT team:

We have analysed 5.5 ks of XRT data for GRB 101008A (Baumgartner et al.
GCN Circ. 11318), from 3169 s to 26.9 ks after the BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position for
this burst was given by Beardmore et al. (GCN. Circ 11321).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.2 (+0.5, -0.3).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.0 (+/-0.5). The best-fitting
absorption column is 2.8 (+2.0, -1.4) x 10^21 cm^-2, in excess of the
Galactic value of 1.4 x 10^21 cm^-2 (Kalberla et al. 2005). The counts
to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from
this spectrum is 4.5 x 10^-11 (6.8 x 10^-11) erg cm^-2 count^-1.

If the light curve continues to decay with a power-law decay index of
1.2, the count rate at T+24 hours will be 1.3 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.9 x
10^-14 (8.9 x 10^-14) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00435903.

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