TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4151
SUBJECT: GRB051021A: Swift XRT refined analysis
DATE:    05/10/23 18:34:01 GMT
FROM:    Judith Racusin at PSU  <racusin@astro.psu.edu>

J. Racusin, D. Fox, D. Burrows (PSU), N. Gehrels (GSFC) on behalf of the 
Swift XRT team:

We have analyzed the first four orbits of data after XRT began observing 
the field of GRB051021A (Yoshida et al., GCN 4116) at 16:28:28 UT.  The 
refined XRT coordinates are:

RA(J2000): 01 56 36.5
Dec(J2000): +09 04 6.1

with an estimated uncertainty of 4 arcseconds (90% containment), including 
corrections for the XRT boresight offset.  This position is 1 arcsecond 
from the position we quoted in Racusin et al. (GCN 4125), and 2.9 
arcseconds from the optical afterglow candidate reported by Fox et al. 
(GCN 4120).

The XRT light curve shows a steady decline with a power-law fit decay 
index of 1.06+/-0.16.

The Photon Counting mode spectra can be fit with an absorbed power-law 
with a photon index of 2.17+/-0.18 and a column density of 1.4+/-0.5 E21 
cm-2 which is in excess of the Galactic column density of 0.56E21 cm-2 in 
this direction.  The observed 0.2-10 keV flux is 2.02E-12 ergs cm-2 s-1, 
corresponding to an unabsorbed flux of 2.28E-12 ergs cm-2 s-1.