GCN Circular 13715
Subject
XMM observations of the short GRB120804A
Date
2012-09-05T19:53:38Z (13 years ago)
From
Raffaella Margutti at Harvard <raffaella.margutti@gmail.com>
R. Margutti (Harvard), V. Mangano (INAF IASF-Palermo), E. Berger, and W.
Fong (Harvard) report:
"We observed the short GRB120804A (GCN 13573) with XMM-Newton
starting on 2012 August 22, 21:51:29 UT (18.8 days after the burst).
GRB120804A is clearly detected at a level of 6 sigma with count-rate of
(4.3 +\- 0.7)e-3 cps (0.2-10 keV) in the pn. The pn net exposure time is
25.5 ks.
Using our best estimate of the intrinsic neutral hydrogen absorption
(NH_int=3.2e21 cm-2) and the Galactic absorption in the direction of the
burst (NH_gal=9.3e20 cm-2, Kalberla et al., 2005), this translates into
an unabsorbed 0.3-10 keV flux of 2.4e-14 erg/s/cm2. Our analysis
does not support the presence of a jet break for t< 18.8 days.
Combining the Swift-XRT (GCN 13580), Chandra (GCN 13640, 13643) and
XMM observations, for t>10^4 s the X-ray afterglow of GRB120804A is
best modeled by a simple power-law decay with index=1.0 +\- 0.1.
We thank the XMM-Newton staff for approving this observation."