MAXI mission for space station and future ASM

MAXI (Monitor of All-sky X-ray Image) is the first astrophysical payload fo r Japanese Experiment Module (JEM) to be designed for all sky X-ray monitor ing. MAXI is a slit scanning camera which consists of two kinds of X-ray de tectors; one is one-dimensional position sensitive proportional counters wi th total area of about 5000 cm(2) there we call GSC) and the other is an X- ray CCD array with total area of about 200 cm(2) (here we call SSC). The GS C subtends a field of view with an angular dimension of 1 degrees x 180 deg rees, while the SSC has a field of view of 1 degrees x 90 degrees. Thus, in the course of one station orbit, MAXI can scan almost all sky with a preci sion of 1 degree and with X-ray energy range of 0.5-30 keV. MAXI with a tot al weight of about 500 kg will be attached to JEM exposed facility (JEM-EF) in 2004. Furthermore, the future ASM with more sensitive detectors having a wide energy band and with better time response/resolution will follow the MAXI mission.