  We describe an XMM-Newton observation of the PKS0312-770 field, which
facilitates the spectral analysis of serendipitous sources previously detected
by CHANDRA. The combination of larger effective area and longer exposure
duration allows a significant increase in detected photons, and a lower limit
in source detection sensitivity. In particular the hard X-ray normal galaxy
unveiled by Fiore et al (2000) is most likely explained as a moderately
absorbed (N_H ~ 1e22 cm^-2) AGN. We detect 52 sources (45 previously
unreported) at a limiting flux of ~2e-15 cgs in the 0.5-2keV band. The
LogN-LogS curve is consistent with that derived from by XMM-Newton observations
of the Lockman Hole field. The flux determinations allow to check for any
inconsistency between the calibrations of the two observatories, which is
discussed.
