GCN Circular 4745

K.L. Page, E. Rol, A.P. Beardmore (U Leicester) and A.J. Levan (U.  
Hertfordshire) report on behalf of the Swift XRT team:

Analysing the first three orbits of data (28 s in Windowed Timing mode and
6.4 ks in Photon Counting mode), the following refined position for the
X-ray afterglow was determined:

RA(J2000) =   05h 00m 17.2s
Dec(J2000) = +14d 56' 58.9"

with an estimated uncertainty of 3.9 arcsec (90% containment). This is 
31.6 arcsec from the on-board BAT position reported in GCN 4739
Not found
 
 
 and 1
Not found
 
 
.9 
arcsec from the XRT position given in GCN 4743
Not found
 
 
.

The light-curve shows a steep initial decay of 2.09 +/- 0.23, flattening
to a slope of 0.62 +/- 0.23 towards the end of the first orbit (at 811 +/-
373 seconds after the trigger).

The spectrum obtained for the first orbit of data (118 - 2380 s
post-trigger) can be fitted with a power-law of photon index Gamma = 1.54
+/- 0.27, assuming a Galactic column of 1.9e21 cm^-2; there is no evidence
for excess NH in these data. Over this time span, the mean 0.3-10 keV
observed (unabsorbed) flux is 4.1e-12 (4.9e-12) erg cm^-2 s^-1.

Assuming the current decay slope of 0.62 continues, and using the spectral
fit to the first orbit of data, the XRT count rate is predicted to be
0.002 at 24 hours, corresponding to an observed (unabsorbed) flux of
8.0e-14 (9.7e-14) erg cm^-2 s^-1. However, taking into account the
uncertainty in the decay slope, the observed flux at 24 hours could range
between (0.3 - 2.4)e-13 erg cm^-2 s^-1.

This circular is an official product of the Swift-XRT Team.