GCN Circular 4402

A. Beardmore (U. Leicester), D. N. Burrows (PSU), K. Page (U. Leicester), 
F. Marshall (GSFC), M. Chester (PSU) report on behalf of the Swift XRT team:

We have analysed the first 3 orbits of XRT data from GRB 051227.
A 2.8ks photon counting mode image provides a refined XRT position:

RA(J2000) =  08h 20m 57.92s,
Dec(J2000) = +31d 55m 30.43s

with an uncertainty of 3.5 arcsec (90% containment). This position is 5.1 
arcsec away from the on-board XRT position quoted in Barbier et al. 
(GCN4397
Not found
 
 
) and includes the latest XRT boresight correction.  This position 
is 106 arcseconds from the refined BAT position (Hullinger et al., GCN 4400
Not found
 
 
).

The X-ray light curve displays multiple small flares, with the largest
peaking at a count rate of approximately 25 counts/s at T + 115s
(where T is the BAT trigger time). The underlying decay can be fit
with a broken power-law with an initial decay slope of -2.2+/-0.2, a
break at 475+235-80s, and a post-break slope of -0.95+/-0.15.

A power-law fit to the X-ray spectrum from T + 101s to T + 180s
gave a photon index of 1.4+/-0.2 and a column density of
(1.8+/-1.0)e21 cm**-2. We note the galactic hydrogen column density in the
direction of the burst is 4.3e20cm**-2. The 0.2-10.0keV observed flux was
4.2e-10 ergs cm**-2 s**-1, which corresponds to an unabsorbed flux of
5.0e-10 ergs cm**-2 s**-1.

If the burst continues decaying at the current rate we estimate an XRT
count rate of 0.0022 counts/s at T + 24hr, which corresponds to an
observed 0.2-10.keV flux of 1.1e-13 ergs cm**-2 s**-1.