[vsnet-grb-info 11327] XMM-Newton observation of the short GRB 111020A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  12739
SUBJECT: XMM-Newton observation of the short GRB 111020A
DATE:    11/12/28 16:55:48 GMT
FROM:    Sergio Campana at INAF-OAB  <sergio.campana at brera.inaf.it>

S. Campana (INAF-Osservatorio astronomico di Brera) reports:

XMM-Newton observed the short GRB 111020A (Sakamoto et al.
2011, GCN 12460) on Oct 20, 2011 21:50:05 UT (15.3 hr after
the burst onset).
The ~20 ks observation was affected in the first part by a mild enhanced
background event which we filtered out. The resulting pn/MOS1/MOS2
exposure times were 15, 17 and 17 ks, respectively.

A source is well detected at a position consistent with the Swift's
(Osborne et al. 2011, GCN 12463) and Chandra's (Berger et al. 2011,
GCN 12492) ones.
The pn count rate is (2.2+/-0.2)x10^{-2}  cts/s.
We extracted 422, 166, and 142 source photons from the pn, MOS1,
and MOS2, respectively.
The spectrum can be fitted with a power law model including a 
non-negligible
absorption component in addition to the Galactic one (6.9x10^{20} cm^{-2}).
The best fit power law implies a photon index of Gamma=1.9+/-0.3
(90% c.l. for one parameter of interest) and an additional column 
density of
NH=(6+/-2)x10^{21} cm^{-2} (90% c.l.). This provides a lower limit to the
intrinsic column density. The reduced chi^2 of the fit is 0.83 (31 d.o.f.).
The unabsorbed 0.5-10 keV is ~2x10^{-13} erg/cm^2/s.