Context :

Aims : We present the Palermo Swift -BAT hard X-ray catalogue obtained from the analysis of the the data relative to the first 39 months of the Swift mission .

Methods : We have developed a dedicated software to perform data reduction , mosaicking and source detection on the BAT survey data .
We analyzed the BAT dataset in three energy bands ( 14–150 keV , 14–30 keV , 14–70 keV ) , obtaining a list of 962 detections above a significance threshold of 4.8 standard deviations .
The identification of the source counterparts was pursued using three strategies : cross-correlation with published hard X-ray catalogues , analysis of field observations of soft X-ray instruments , cross-correlation with the SIMBAD databases .

Results : The survey covers 90 % of the sky down to a flux limit of 2.5 \times 10 ^ { -11 } erg cm ^ { -2 } s ^ { -1 } and 50 % of the sky down to a flux limit of 1.8 \times 10 ^ { -11 } erg cm ^ { -2 } s ^ { -1 } in the 14–150 keV band .
We derived a catalogue of 754 identified sources , of which \sim 69 % are extragalactic , \sim 27 % are Galactic objects , \sim 4 % are already known X-ray or gamma ray emitters whose nature has not been determined yet .
The integrated flux of the extragalactic sample is \sim 1 \% of the Cosmic X-ray background in the 14–150 keV range .

Conclusions :