[vsnet-grb-info 3252] GRB 060507: Swift XRT Team Refined Analysis

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5087
SUBJECT: GRB 060507: Swift XRT Team Refined Analysis
DATE:    06/05/07 17:10:01 GMT
FROM:    Loredana Vetere at ASDC  <vetere at asdc.asi.it>

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


We have analysed the first 5 orbits of XRT data from GRB 060507
(Barbier et al., GCN 5084).
A 11ks photon counting mode image provides a refined XRT position:

RA(J2000)  =  05 59 51.7
Dec(J2000) = +75 14 56.6

with an uncertainty of 4 arcsec (90% containment). This is 1 arcsec
away from the initial XRT position quoted in GCN 5085 (Vetere et al.).

The X-ray light curve decays with a single powerlaw, fitting the last
4 orbits we find a decay index of  -1.0 +/- 0.1.

A power-law fit to the X-ray spectrum from T+2.8ks to T+28.3ks gives a
photon
index of 2.1+/-0.1 and a column density of (1.7+/-0.4)e21 cm^-2. We note
that the galactic hydrogen column density in the direction of the burst
is 8.8e20cm^-2. The 0.2-10.0 keV observed flux is 2.2e-12 ergs
cm^-2 s^-1, which corresponds to an unabsorbed flux of 3.4e-12 ergs
cm^-2 s^-1.

If the burst continues decaying at the current rate we estimate an XRT
count rate of  0.009 counts/s at T + 24hr, which corresponds to an
observed 0.2-10.keV flux of 6.8e-13 ergs cm^-2 s^-1.

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