SKY SURVEYS WITH ASCA - LARGE SKY SURVEY

We have carried out the first systematic wide-area survey around a Gal actic pole region with the ASCA satellite in the 0.7-10 keV energy ban d (Large Sky Survey; LSS). The observed area amounts to 7 deg(2). To m ake the best use of ASCA capability, we have developed a new source-de tection method where the complicated detector responses are fully take n into account. Applying this method to the entire LSS data independen tly in three energy bands (0.7-2 keV, 2-10 keV, and 0.7-7 keV), we det ected 104 sources in total (4.5 sigma detection). The Log N - Log S re lation and spectral properties of faint sources are presented.