The High Pressure Gas Scintillation Proportional Counter (HPGSPC) is one of the Narrow Field Instruments of the Italian-Dutch X-ray astronomy satellite SAX. Sensitive in the hard X-ray band (4–120 keV), with a very good energy
resolution, the HPGSPC is well suited for studying in detail the cyclotron features present in the hard X-ray spectrum of some celestial sources. The scientific
calibration of the flight model of the HPGSPC took place at the LABEN premises(Vimodrone-Milano) during October and November 1994. In this paper we briefly describe the
on-ground instrument calibration system and we report some
preliminary results that show the performances of both single/double event and position reconstruction/energy correction onboard processing. Preliminary results
concerning the energy resolution and energy linearity are reported too
