[vsnet-grb-info 9385] GRB 100619A: Swift-XRT refind analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  10866
SUBJECT: GRB 100619A: Swift-XRT refind analysis
DATE:    10/06/19 12:07:18 GMT
FROM:    Jirong Mao at INAF-OAB  <jirong.mao at brera.inaf.it>

J. Mao (INAF-OAB) and J. K. Cannizzo (NASA/UMBC) report on behalf of the
Swift-XRT team:

We have analysed 6.6 ks of XRT data for GRB 100619A (Cannizzo  et al.
GCN Circ. 10863), from 80 s to 13.2 ks after the  BAT trigger. The data
comprise 492 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The light curve initially shows a flare feature
at the time 90s, then it has a power-law decay with an index 0.88, after 
that,
the light curve shows a clear flare feature with the peak at 1000s. 
Then, the
light cure has a power-law decay with an index of alpha=0.85 (+/-0.02).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.41 (+/-0.03). The
best-fitting absorption column is  3.4 (+/-0.1) x 1021 cm^-2, in
excess of the Galactic value of 2.0 x 1020 cm^-2 (Kalberla et al.
2005). The PC mode spectrum has a photon index of 2.16 (+0.20, -0.19)
and a best-fitting absorption column of 3.7 (+/-0.6) x 1021 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 6.7 x 10^-11 (9.6 x 10^-11) erg cm^-2
count^-1. If the light curve continues to decay with a power-law decay 
index
of 0.85, the count rate at T+24 hours will be 0.015 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.0 x
10^-12 (1.4 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00424998.

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