An XMM-Newton view of the serendipitous sources in the PKS0312-770 field

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 similar to 10(22) cm(-2)) AGN. We detect 52 sources (45 previously unreported) at a limiting flux of similar to2 x 10(-15) ergs cm(-2) s(-1) in the 0.5-2 keV band. The Log N-Log S 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.