[vsnet-grb-info 6854] GRB080229: Swift XRT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8446
SUBJECT: GRB080229: Swift XRT refined analysis
DATE:    08/10/29 11:10:09 GMT
FROM:    Jirong Mao at INAF-OAB  <jirong.mao at brera.inaf.it>

GRB080229: Swift XRT refined analysis

J. Mao, R. Margutti, C. Guidorzi (INAF-OAB) and T. Sakamoto (NASA/ UMBC)
report on behalf of the Swift-XRT team:

We have analysed the first 3 orbits of Swift-XRT data obtained for
GRB 081029 (Sakamoto et al., GCN Circ. 8435).
 From T+2.7 to T+16.7 ks after the burst, data were collected in Photon
Counting (PC) mode with a total net exposure of 7 ks.
The UVOT-enhanced position was given by Goad et al. in GCN Circ. 8443.

The light curve shows a decay that can be fit with a simple power law
with an index of 0.57 +- 0.05.

The PC spectrum accumulated between T+2.7 and T+16.7 ks can be fit with a
absorbed power-law model with a photon index of 1.9 +- 0.1 and an
absorbing equivalent hydrogen column density consistent with the
Galactic one in the GRB direction (2.7e20 cm^-2; Kalberla et al.  2005).
The observed (unabsorbed) 0.3-10 keV flux is 6.9(7.5)e-12 erg cm^-2  s^-1.

If the light-curve continues to decay with alpha ~ 0.57, the count  rate 24
hours after the burst is estimated to be 0.03 count s^-1, which
corresponds to an observed flux of 2.1e-12 erg cm^-2 s^-1.

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