GCN Circular 8028
Subject
GRB 080727A: Swift-XRT refined analysis
Date
2008-07-27T15:30:20Z (17 years ago)
From
Kim Page at U.of Leicester <kpa@star.le.ac.uk>
K.L. Page, J.P. Osborne (U. Leicester) and S. Immler (CRESST/GSFC/UMD)
report on behalf of the Swift-XRT team:
We have analysed the first three orbits of data obtained for GRB 080727A
(Immler et al., GCN Circ. 8021), covering 7 ks of Photon Counting mode
data. The UVOT-enhanced position has been given by Evans et al. (GCM Circ.
8025).
During the first orbit (117s - 1.9 ks after the trigger), the light-curve
shows a number of small flares, superimposed on a power-law decay of
alpha= 2.01 +0.18/-0.17. The source is no longer detected in the combined
second and third orbits of data (5.3 ks of exposure time, starting 5 ks
after the trigger). Although the upper limit is consistent with the
continued decay of alpha = 2.01, it is not possible to determine whether a
break has occurred.
The spectrum from the first orbit of data can be fitted with a power-law
of Gamma = 1.43 +0.20/-0.19, absorbed by the Galactic column in this
direction (6.75x10^20 cm^-2). The average observed (unabsorbed) flux over
this time is 5.56 (6.02) x 10^-12 erg cm^-2 s^-1. The counts to observed
flux conversion is 5.3 x 10^-11 erg cm^-2 count^-1.
With the limited information available from a detection only in the first
orbit, we are unable confidently to predict the flux at 24 hours.
This is an official product of the Swift-XRT team.