[vsnet-grb-info 3743] GRB060919: XRT refined analysis

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5577
SUBJECT: GRB060919: XRT refined analysis
DATE:    06/09/19 14:45:47 GMT
FROM:    Cristiano Guidorzi at INAF-OAB  <cristiano.guidorzi at brera.inaf.it>

C. Guidorzi, P. Romano, A. Moretti, S. Vergani on behalf of the
Swift XRT team report:


we have analysed the first orbit of XRT data from GRB 060919
(Guidorzi et al., GCN Circ 5575). A 1.3 ks Photon Counting mode image
provides a refined XRT position:

RA(J2000)  =  18h 27m 42.21s,
Dec(J2000) = -51d 00m 50.4s

with an uncertainty of 4.1 arcsec (90% containment). This position is 1.6
arcsec away from the previous XRT position and 56 arcsec from the onboard
BAT position (Guidorzi et al., GCN Circ 5575).

The X-ray light curve can be fit with a single power law with index
0.85 +- 0.2 (90%) from 100 to 1400 seconds after the BAT trigger.

A power-law fit to the 0.3-10 keV spectrum yields a photon index
of 1.7+-0.5 and a column density of (9+-4)x1e21 cm-2 (90%),
significantly in excess of the Galactic hydrogen column density
in the direction of the burst (6.4e20cm-2).

The average unabsorbed flux of the first orbit is (1.1+-0.3)e-11 erg 
cm-2 s-1.
If the burst decays at the current rate we estimate a
0.3-10 keV unabsorbed flux of ~1.2e-13 ergs cm-2 s-1 at T+24hr.

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