[vsnet-grb-info 14591] GRB 140301A: Swift-XRT refined Analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15905
SUBJECT: GRB 140301A: Swift-XRT refined Analysis
DATE:    14/03/02 12:03:17 GMT
FROM:    Kim Page at U.of Leicester  <klp5 at leicester.ac.uk>

K. L. Page (U Leicester) reports on behalf of the Swift-XRT team:

We have analysed 5.9 ks of XRT data for GRB 140301A (Page  et al. GCN
Circ. 15896),  from 92 s to 51.3 ks after the  BAT trigger. The data
comprise 382 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Goad et al. (GCN Circ. 15898).

The late-time light curve (from T0+6.4 ks) can be modelled with  a
power-law decay with a decay index of alpha=0.95 (+0.32, -0.29).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 2.01 (+/-0.09). The
best-fitting absorption column is  3.3 (+/-1.0) x 10^21 cm^-2, at a
redshift of 1.416, in addition to the Galactic value of 2.2 x 10^20
cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index
of 2.42 (+0.32, -0.29) and a best-fitting absorption column of 7.2
(+4.1, -3.3) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10
keV flux conversion factor deduced from this spectrum  is 3.0 x 10^-11
(4.8 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 2.2 x 10^20 cm^-2
Intrinsic column:    7.2 (+4.1, -3.3) x 10^21 cm^-2 at z=1.416
Photon index:	     2.42 (+0.32, -0.29)

If the light curve continues to decay with a power-law decay index of
0.95, the count rate at T+24 hours will be 5.8 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x
10^-13 (2.8 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00589590.

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