[vsnet-grb-info 4661] GRB070517: Swift-XRT Refined Analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6414
SUBJECT: GRB070517: Swift-XRT Refined Analysis
DATE:    07/05/17 23:42:11 GMT
FROM:    Susanna Vergani at INAF/Brera  <vergani at brera.inaf.it>

S.D. Vergani (DIAS-DCU) and P. Romano (INAF-OAB) report
on behalf of the Swift Team:

We have analysed the first four orbits of Swift XRT data from GRB070517
(trigger number 279494, GCN Circ. 6411) for a total of 8.9ks.
The refined XRT position is

RA/Dec(J2000) = 18h 30m 29.0s   -62d 17' 51.7"  which is
RA/Dec(J2000) = 277.6207   -62.2977

with an uncertainty of 3.7 arcsec (radius, 90% containment).
This position lies 3.5 arcsec from the XRT position and 2.4 arcmin from
the BAT position given in GCN Circ. 6411 (Vergani et al.).

The XRT PC light curve of the firts four orbits presents a flaring behaviour.
A tentative fit with a power law gives a decay index alpha=0.4 +/- 0.1

The X-ray spectrum of the PC data can be fitted using an
absorbed power law (photon index = 1.95 +/-0.07) with an absorbed column
density fixed to the Galactic value (8.6e20 cm^-2; Dickey & Lockman,
1990). The absorbed (unabsorbed) 0.3-10.0keV flux for this spectrum
was 1.9E-12 (2.3E-12) ergs cm^-2 s^-1.

Assuming the source continues to decay at the same rate, we predict
an XRT count rate of 1.8E-2 counts/s at T+24 hours, which corresponds
to an observed flux of about 9E-13 ergs cm^-2 s^-1.

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