[vsnet-grb-info 5905] GRB080330: Swift XRT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7555
SUBJECT: GRB080330: Swift XRT refined analysis
DATE:    08/03/31 12:26:12 GMT
FROM:    Jirong Mao at INAF-OAB  <jirong.mao at brera.inaf.it>

GRB080330: Swift XRT refined analysis

 J. Mao, A. Moretti, and C. Guidorzi (INAF-OAB) report on behalf of the Swift-XRT team:
 
We have analysed the Swift-XRT data obtained for BAT GRB 080330 (trigger #308041, Mao et al., GCN Circ. 7537). The data consist of 57 s in Windowed Timing (WT) mode, starting 77s after the BAT trigger and 1.36 ks in Photon Counting (PC) mode. The best X-ray position is given in Burrows GCN 7541.

The XRT light-curve can be fit by a power-law with a slope of alpha1=5.22+/-0.30 up to a break at t=167.9+/-7.3 s, which is followed by a shallow decay with a slope of alpha2=0.20+/-0.07.
 
The spectrum formed from all the WT data can be modeled with a power-law of photon index Gamma=2.03+/-0.09, with the fixed absorbing Galactic column of NH=1.23e20 cm^-2. The spectrum formed from the PC data can be modeled with a power-law of photon index Gamma=1.91 ±0.09, with an absorbing column of NH=(2.78+/-1.22)e21 cm^-2 (in excess with respect to the Galactic value of 1.23e20 cm^-2).

If the light-curve continues to decay with a slope of 0.20, after 48 hours, the light curve will have count rate of 0.18 count s^-1, corresponding to an observed (unabsorbed) flux of 5.4e-12(1.3e-11) ergcm^-2 s^-1. 

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