Sky surveys with ASCA - Large Sky Survey

We have carried out the first systematic wide-area survey around a Galactic pole region with the ASCA satellite in the 0.7-10 keV energy band (Large Sky Survey; LSS). The observed area amounts to 7 deg(2). To make the best use of ASCA capability, we have developed a new source-detection method where the complicated detector responses are fully taken into account. Applying this method to the entire LSS data independently in three energy bands (0.7-2 keV, 2-10 keV, and 0.7-7 keV), we detected 104 sources in total (4.5 sigma detection). The Log N - Log S relation and spectral properties of faint sources are presented.