We have made deep ROSAT exposures (80ksec) in a field at the SGP.
 Optical follow-up first showed that many of the X-ray sources
 detected are QSOs accounting for 30-50% of the 1keV X-ray
 background. At fainter fluxes (S(0.5-2keV)=3x10-14 ergs cm-2s-1)
 we detect an increasing number of apparently normal galaxies. These
 galaxies could account for as large a fraction of the 1keV background
 as the QSOs but the X-ray emission mechanism for these galaxies is
 currently unknown. First we are proposing to make ISOPHOT observations
 of 14 X-ray luminous SGP galaxies at 60 and 100um to detect the dust
 that may be present and assess the amount of star forming activity
 taking place to distinguish between models for the x-ray emission.
 Second, we are proposing to make ISOPHOT observations of a complete
 X-ray selected sample of 16 QSOs in the same field to characterise
 the FIR properties of typical, radio quiet QSOs at fainter
 luminosities and higher redshifts than has previously been possible.
 We also propose to study the (restframe) near IR emission of a
 subsample of high redshift QSOs to test claims of an underlying power
 law continuum correlating near IR and x-ray luminosity.