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   PR # 11191
    We propose a survey observation of a large sky area, 3.3deg2, to flux
    limit of 6e-14 erg/cm2/sec in AO-1.Optical follow-up will be made alo
    ng with the observation.The flux limit is much deeper than large-area
    /all sky surveys available to now,& the area is substantially larger
    than the ROSAT DeepSurvey so far achieved. We expect 100 sources in
    AO-1.The unique features are the observation in a higher energy band,
    with which we expect different skyfrom ROSAT's.The scientific goal is
    "X-ray cosmology" with a deep X-rayselected catalogue. Specific aims
    are multifold with immediate interests including logS-logN relation,
    luminosity function,evolution and large scale clustering of QSO/AGN's
    , and evolution of galaxy clusters, fluctuation and large scale struc
   ture of CXB.
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