[vsnet-grb-info 3016] GRB060218: analysis of the XMM-Newton observation

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4853
SUBJECT: GRB060218: analysis of the XMM-Newton observation
DATE:    06/03/06 19:28:13 GMT
FROM:    Andrea De Luca at IASF-CNR,Milano  <deluca at iasf-milano.inaf.it>

Andrea De Luca (INAF/IASF, Milano) on behalf
of a larger collaboration reports:

We have analyzed the XMM-Newton observation
of the field of GRB060218, discovered by 
Swift/BAT on 2006, February 18 at 03:34:30 UT 
(GCN4775, Cusumano et al.)

The XMM-Newton observation started on 2006,
February 20 at 17:21:45 UT (~61.8 hours after
the GRB trigger) and lasted for 14 ks.
The observation is affected by a high
particle background, which hampers a detailed    
temporal and spectral analysis of the faint X-ray
afterglow.

We report here on data collected by the EPIC/pn camera.
spanning the time range 223.9-234.9 ks after the trigger.

The afterglow of GRB060218 is detected at the 
following coordinates: 
RA(J2000): 03h 21m 39.63s, Dec(J2000): 16d 52' 03.4"
with an uncertainty of 1.2 arcsec (1sigma),
fully consistent with the coordinates of the 
optical (GCN4779, Marshall et al.) and radio 
(GCN4828, Soderberg & Frail) afterglow, as well as 
with the Swift/XRT position (GCN4786, Cusumano et al.).

Extracting source events from a circle of 10 arcsec
radius (containing ~50% of the total counts) the pn
time-averaged, background-subtracted count rate in the 
0.5-8 keV range is of 0.017+/-0.002 cts/s.
No significant fading of the X-ray flux is detected along
the XMM-Newton observation.

The time-integrated X-ray spectrum is well fit 
(reduced chi2=0.98, 14 d.o.f.) by a steep power
law absorbed by the Galactic column (NH=1.1e21 cm^-2,
Dickey & Lockman, 1990), with a photon index Gamma=3.3+/-0.6 
(90% conf. level for a single parameter). 
The observed flux (0.5-10 keV) is of 5.7x10^-14 erg 
cm^-2 s^-1, corresponding to an unabsorbed flux of 
8.4x10^-14 erg cm^-2 s^-1.