Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 6167

GRB070227: Swift-XRT refined analysis
2007-03-05T21:07:47Z (17 years ago)
Claudio Pagani at PSU/Swift-XRT <>
C. Pagani, J. L. Racusin, L. Vetere, D. Grupe, D. N. Burrows (PSU), report on 
behalf of the Swift XRT team:

We have analysed the Swift-XRT Photon Counting data of GRB 070227 (GCN Circ. 
6156) from T+56ks to T+386ks (where T is the BAT trigger time). The candidate 
X-ray afterglow reported in GCN Circ. 6157 has faded from the initial count 
rate of ~ 0.01 counts/s to a count rate of 0.002 counts/s. 
Using 39ks of PC data the refined XRT position is RA,Dec= 120.5805, -46.3135 
which is:

RA(J2000): 08h 02m 19.33s
Dec(J2000): -46d 18' 48.7"

with an uncertainty of 4 arcseconds (90% containment).  This position is 47 
arcseconds from the refined BAT position given in GCN Circ. 6158 and 0.7 
arcseconds from the XRT position given in GCN Circ. 6157. 

The light-curve shows an initial flat phase during the first 20ks of XRT 
obervations ending at about 80ks after the burst, followed by a decay that can 
be fitted with a power law with index 0.9+/-0.2.

The spectral fit to the PC data is not very well constrained due to the low 
number of afterglow events.  The fit with an absorbed power law, applying 
C-statistics, gives a photon index of 2.9 (+0.8/-0.5) in the [0.3-10] keV 
band, and a column density of (0.57 +0.26/-0.18)e22 cm^-2 (compared with the 
Galactic value in this direction of 0.31e22 cm^-2).  
The average estimated unabsorbed 0.3-10 keV flux from T+56ks to T+386ks of XRT 
Photon Counting observations was 3.6e-13 erg cm^-2 s^-1.

This Circular is an official product of the Swift XRT Team.
Looking for U.S. government information and services? Visit