GCN Circular 8185
Subject
GRB 080905A: Swift-XRT Refined Analysis
Date
2008-09-06T02:31:56Z (16 years ago)
From
Claudio Pagani at PSU/Swift-XRT <pagani@astro.psu.edu>
C. Pagani and J. Racusin (PSU) report on behalf of the Swift-XRT team:
We have analyzed the first orbit of Swift-XRT data for the short GRB 080905A
(Pagani et al., GCN 8180) beginning at T0+130 seconds to T0+1.1 ks.
The enhanced XRT position given in GCN Circ 8180 is 40 arcseconds from the BAT
onboard position, within the BAT error circle.
The XRT lightcurve shows an initial count rate of approximately 6 counts/s for
the first 100 seconds of observations, followed by a steep decay and a
shallower phase. The decaying lightcurve can be fit with a broken power-law
with an initial decay index of 6.4+/-2.0, a break at approximately T0+400
seconds and a later decay index of 1.0+/-0.5.
The spectrum of 1 ks of Photon counting mode data from the first orbit can be
fit by an absorbed power-law with a photon index of 1.3+/-0.3 and absorption
consistent with the Galactic value along the line of sight (9e20 cm^-2,
Kalberla et al. 2005). The average observed (unabsorbed) flux of the PC mode
data is 2.9e-9 (3.1e-10) ergs cm^-2 s^-1.
Assuming the X-ray emission continues to decline at the same rate, we predict a
0.3-10.0 keV XRT count rate of 0.001 counts/s at T+24hr, which corresponds to
an observed flux of 7e-14 ergs cm^-2 s^-1.
This Circular is an official product of the Swift-XRT team.