The Palermo Swift-BAT Hard X-ray Catalogue Results After 54 Months of Sky Survey

The Burst Alert Telescope (BAT 14-150 keV) on board of Swift is mainly devoted to the monitoring of a large fraction of the sky (50%-80% per day) for the occurrence of Gamma Ray Bursts. This provides the opportunity for a substantial gain of our knowledge of the Galactic and extragalactic sky in the hard X-ray domain. Here we present the Second Palermo Swift-BAT hard X-ray catalogue (http //bat.ifc.inaf.it), obtained from the analysis of the data relative to the first 54 months of the Swift mission and including about 1300 BAT sources, 1100 of them associated to a softer counterpart using a large follow-up campain with Swift/XRT. The BAT catalogue includes 62.5% of extragalactic objects, 22.5% of Galactic objects and 15% of known Xray emitters whose nature has not been determined yet. We cross-correlated this sample with Rosat all-sky survey and the Fermi catalogue. Broad band spectral analysis is presented for the different classes of extragalactic sources.