GCN Circular 5209

A.P. Beardmore, O. Godet (U. Leicester) and T. Sakamoto  (GSFC/ORAU) 
report on behalf of the Swift-XRT team :

We have analysed the first 11.4ks of Swift XRT PC mode data from the BAT
trigger GRB060602B (Schady et al., GCN 5200
Not found
 
 
; trigger number 213190). We 
find a refined XRT position of:

RA(J2000)  =  17:49:31.6
Dec(J2000) = -28:08:03.2

with an estimated uncertainty of 3.7 arcsec (90% containment). This is
1.4 arcsec away from the XRT position reported in GCN 5200
Not found
 
 
 and 64
Not found
 
 
.2 
arcsec from the refined BAT position (Palmer et al., GCN 5208
Not found
 
 
).

The X-ray light curve shows a small rise in intensity until T+200s, then 
follows a simple power-law decay with a index of 1.05 +/- 0.07.

The X-ray spectrum over the same interval (T+100s to T+40ks) can be well 
modelled by an absorbed power-law, with a photon index of 3.1 +/- 0.6 
and a column density of 5.0 +/- 1.4 E22 cm^-2. The measured galactic 
column density in this direction is 1.4E22 cm^-2. The observed 0.3-10keV 
flux is 3.2E-12 ergs cm**-2 s**-1, which corresponds to an unabsorbed 
flux of 5.0E-11 ergs cm**-2 s**-1. The measured spectral and temporal 
indices are difficult to reconcile with standard GRB afterglow models.

The X-ray spectrum can also be equally well fit by an absorbed blackbody 
model, with a temperature of 0.90+/-0.09 keV and a column density of 2.1 
+/- 0.7 E22 cm^-2. This model has an observed (unabsorbed) 0.3-10 keV flux 
of 2.8E-12 (4.3E-12) ergs cm**-2 s**-1.

Assuming the source decays at the same rate, we predict an XRT count 
rate of 0.0011 count/s at T+48 hrs, which corresponds to an  observed 
flux of 8.8E-14 ergs cm**-2 s**-1.

This Circular is an official product of the Swift XRT Team.