[vsnet-grb-info 9975] GRB 101201A: Swift-XRT refined Analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  11432
SUBJECT: GRB 101201A: Swift-XRT refined Analysis
DATE:    10/12/02 15:51:21 GMT
FROM:    Phil Evans at U of Leicester  <pae9 at star.le.ac.uk>

V. Mangano (INAF/IASF Pa), B. Sbarufatti (INAF/OAB - IASF Pa) report on=0A=
behalf of the Swift-XRT team:=0D=0A=
=0D=0A=
We have analysed 4.9 ks of XRT data for GRB 101201A (Cummings  et al.=0A=
GCN Circ. 11429), from 51.2 ks to 69.7 ks after the  BAT trigger. The=0A=
data are entirely in Photon Counting (PC) mode. Using 3879 s of PC mode=0A=
data and 3 UVOT images, we find an enhanced XRT position (using the=0A=
XRT-UVOT alignment and matching UVOT field sources to the USNO-B1=0A=
catalogue): RA, Dec =3D 1.96750, -16.18540 which is equivalent to:=0D=0A=
=0D=0A=
RA (J2000): 00h 07m 52.21s=0D=0A=
Dec(J2000): -16d 11' 07.4"=0D=0A=
=0D=0A=
with an uncertainty of 1.9 arcsec (radius, 90% confidence).=0D=0A=
=0D=0A=
The light curve can be modelled with  a power-law decay with a decay=0A=
index of alpha=3D3.80 (+0.03, -1.25).=0D=0A=
=0D=0A=
A spectrum formed from the PC mode data can be fitted with an absorbed=0A=
power-law with a photon spectral index of 2.4 (+0.7, -0.6). The=0A=
best-fitting absorption column is  8 (+14, -6) x 10^20 cm^-2,=0A=
consistent with the Galactic value of 2.2 x 10^20 cm^-2 (Kalberla et=0A=
al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux=0A=
conversion factor deduced from this spectrum  is 3.2 x 10^-11 (4.6 x=0A=
10^-11) erg cm^-2 count^-1. =0D=0A=
=0D=0A=
A summary of the PC-mode spectrum is thus:=0D=0A=
Total column:	     8 (+14, -6) x 10^20 cm^-2=0D=0A=
Galactic foreground: 2.2 x 10^20 cm^-2=0D=0A=
Excess significance: <1.6 sigma=0D=0A=
Photon index:	     2.4 (+0.7, -0.6)=0D=0A=
=0D=0A=
If the light curve continues to decay with a power-law decay index of=0A=
3.80, the count rate at T+24 hours will be 4.9 x 10^-3 count s^-1,=0A=
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.6 x=0A=
10^-13 (2.2 x 10^-13) erg cm^-2 s^-1.=0D=0A=
=0D=0A=
The results of the XRT-team automatic analysis are available at=0A=
http://www.swift.ac.uk/xrt_products/00020152.=0D=0A=
=0D=0A=
This circular is an official product of the Swift-XRT team.=0D=0A=
=0A=