The K-Band Luminosity Function
Investigations of broad band energy distributions of specific classes of sources requires homogeneous samples of a sufficiently large number of objects. Deep and homogeneous surveys in those energy ranges which are accessible to satellites only are rare. One such a field in the north ecliptic pole (NEP). The ROSAT and IRAS whole sky surveys and deep additional observations by other satellites make the NEP the region of the deepest mid-IR and X-ray observations. We performed complete surveys in three optical/IR colors at 460nm, 700nm, and 2.1/μm (B, R, and K’) within a one square degree field around the NEP. Limiting magnitudes in the three bands are 23, 24, and 19, respectively. The optical bands are observed with sufficient spatial sampling to classify extended and point sources. Down to levels which still correspond to high completeness limits we detect 80.000, 240.000 and 25.000 sources in B, R, and K’, respectively.