TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5010
SUBJECT: GRB060427: Swift XRT Team refined analysis
DATE:    06/04/27 17:55:36 GMT
FROM:    Vanessa Mangano at INAF-IASFPA  <vanessa@ifc.inaf.it>

V. Mangano (INAF-IASFPA), G. Tagliaferri (INAF-OAB),
D. N. Burrows (PSU) report on behalf of the Swift XRT Team:


We have analyzed the first orbit data of GRB060417
(Mangano et al 2006, GCN 5006).
The XRT data set consists of 88 s exposure in Windowed
Timing (WT) mode followed by 843 s exposure in Photon
Counting (PC) mode.

The refined position of the source is

    RA  (2000) =  08h 17m  04.4s  
    Dec (2000) = +62d 40'  18.3"

with an uncertainty of 3.4 arcsec (90% confinement).
This position is only 1 arcsec from the onboard
detected position (Mangano et al 2006, GCN 5006).

The 0.2-10 keV X-ray light curve shows an initial very
fast decay with slope -4.3 +/- 0.2, a break at 247 +/- 12 s
from the trigger and a final decay slope of -1.7 +/- 0.13.

The WT and PC spectra were fitted separately with an
absorbed power law model and showed photon indices of
2.9 +/- 0.1 and 2.37 +/- 0.14, respectively (90% confidence level).
The WT spectrum, covering the time interval 138-227 s, accounts
for the pre-break phase of the light curve.
Both spectra show evidence of an absorption column at the
level of (1.7 +/- 0.2) x 10^21 cm^-2 in excess with respect
to the Galactic value of 4.3 x 10^20 cm^-2.
The 0.2-10 keV unabsorbed fluxes of the two spectra are
1.3 x 10^-9 and 6.6 x 10^-11 erg cm^-2 s^-1, respectively.

If decaying at the present rate the source will reach the
flux level of 10^-14 erg cm^-2 s^-1 (corresponding to
a count rate level of 1.5 x 10^-4 counts s^-1)
after one day.

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