[vsnet-grb-info 8392] GRB 090912: Swift-XRT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9910
SUBJECT: GRB 090912: Swift-XRT refined analysis
DATE:    09/09/13 20:38:38 GMT
FROM:    Boris Sbarufatti at INAF-IASF-Pa  <sbarufatti at ifc.inaf.it>

Sbarufatti B., Mangano V. (INAF-IASFPA) and T. Ukwatta (GSFC/GWU)
report on behalf of the Swift Team:

We have analyzed the first 22.5 ks of of Swift-XRT data of
GRB 090912 (trigger 362633; Ukwatta, et al., GCN Circ. 9905).
The data are entirely in Photon Counting (PC) mode, from T+806 s to
T+66 ks. The enhanced XRT position for this burst was given by
Beardmore et al. (GCN. Circ 9906).

The 0.3-10 keV X-ray light curve is best fitted by a power-law
with decay index -0.75+/-0.03. Faint flaring activity is
detected along the decay. If decaying at the present rate, the
predicted rate for T+ 48h is 1.0e-2 counts/s.

The average spectrum is best fit by a power-law with index
2.1+/-0.1. The absorbing column is NH = (5.2+/-0.7)E20 cm^-2,
in excess with respect to the Galactic value of 1.3E20 cm^-2
(Kalberla et al. 2005). The average observed (unabsorbed) fluxes are
3.0(5.7)E-12 ergs cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00362633 .

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