TITLE:   GCN CIRCULAR
NUMBER:  5602
SUBJECT: GRB 060923B: Swift XRT Refined Analysis
DATE:    06/09/24 00:24:19 GMT
FROM:    Milvia Capalbi at ISAC/ASDC  <capalbi@asdc.asi.it>

M. Capalbi, M. Perri , M.L. Conciatore (ASDC), D.N. Burrows (PSU) and M. 
Stamatikos (NASA/ORAU) report on behalf of the Swift XRT team:


We have analysed the first 2 orbits of XRT data from GRB 060923B 
(Stamatikos et al., GCN Circ. 5590) with a total exposure of 2.1ks in 
photon counting mode. The refined position is:

RA(J2000)  =  15h 52m 46.83s,
Dec(J2000) = -30d 54m 11.9s

with an uncertainty of 6 arcsec (90% containment). This position is 0.7 
arcsec from the one calculated from early downlinked data (Stamatikos et 
al., GCN Circ. 5590).

The 0.3-10.0 keV X-ray light curve can be fit with a single power-law 
with a slope of -0.7+/-0.1.

A power-law fit to the X-ray spectrum from T + 125s to T + 365s gives a 
photon index of 1.7+/-0.5, fixing the hydrogen column density to the 
galactic value in the direction of the burst (8.8e20cm**-2). The 
0.3-10.0 keV observed flux is 8.5e-12 ergs cm**-2 s**-1, which 
corresponds to an unabsorbed flux of 8.9e-12 ergs cm**-2 s**-1.

If the burst continues decaying at the current rate we estimate an XRT 
count rate of 0.014 counts/s at T + 24hr, which corresponds to an 
observed 0.3-10.keV flux of  5.6e-13 ergs cm**-2 s**-1.

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