Swift/XRT observation of the Crab Nebula after the gamma-ray flare observed on April 11, 2011
ATel #3279; G. Cusumano (INAF-IASF Palermo), V. La Parola (INAF-IASF Palermo), P. Romano (INAF-IASF Palermo), D. N. Burrows (PSU), J. M. Gelbord (PSU) on behalf of the Swift XRT team
on 13 Apr 2011; 21:37 UT
Credential Certification: Valentina La Parola (laparola@ifc.inaf.it)
Subjects: X-ray, Gamma Ray, Pulsar
Referred to by ATel #: 3286
Following the detection by the Fermi/LAT (ATel #3276) of an enhanced gamma-ray
emission from a source positionally consistent with the Crab Nebula,
a ToO Swift/XRT observation was requested. We obtained 1.8 ks XRT observation
of the Crab Nebula in windowed timing (WT) mode starting at 2011-04-12
18:39:29 UT. In this observation the peak emission of the Crab Nebula is coincident with
a hot column. The XRT software allows
a proper correction for the presence of hot columns for point-like sources. In order to
avoid any systematics due to the application of this correction to an extended source,
we extracted the data excluding manually the small region affected by the hot column in
order to properly compare the results with those produced in previous Crab observations
that, for this purpose, were extracted with the same spatial selection.
A preliminary spectral analysis gives flux and spectral parameters well within the values range measured in previous Swift/XRT Crab observations.
