The ISOPHOT Data Centre (IDC) is being established at MPIA Heidelberg, forming one component in the cluster of ESA's and national PI data centres, which will be built up as part of the ISO project. During the mission and in the post mission phase the IDC will closely collaborate with ESA and support the PHT Instrument Dedicated Team at Villafranca. Its main tasks will be rapid scientific data analysis and continuous improvement of the instrument calibration incorporating laboratory data. Special tasks will be the PHT Serendipity Mode processing and evaluation and the development of a comprehensive data base of the IR sky brightness including the Zodiacal Light, Cirrus and Extragalactic Background emission. After the mission the IDC will provide a complete ISOPHOT data base, which will be available for remote access.
The ISOPHOT Flight Spare Unit (FS) has been upgraded and completely characterised in November 1994 during a ground calibration campaign. The replacement of the P1 and P2 Si:Ga/Si:B bulk detectors, which are contained in the Flight Unit (FM), by Si:As BIB detectors has let to a significant increase in performance with respect to the FM. The new BIB detectors have improved sensitivity, a faster response and are less affected by irradiation in the earth's radiation belts.