GCN Circular 8028

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
Not found
 
 
), 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.