High Energy X-Ray Sky Observation by the Formation Flight All Sky Telescope

We are planning to have a “formation flight all sky telescope” (FFAST) that will cover a large fraction of the whole sky area in relatively high energy X-ray. In particular, it will focus on the energy range above 10 keV. It consists of two small satellites that will go in a formation flight. One is the X-ray telescope satellite and the other is the detector satellite. Two satellites will be simultaneously launched by a single rocket vehicle into a low earth orbit. They are in a formation flight with a separation of 20 m ± 10 cm. The observation direction is determined by the two satellites. Since two satellites are put into the Keplerian orbit, the observation direction is scanning the sky rather than pointing to a fixed direction. One satellite carries an X-ray telescope covering the energy range up to 80 keV. The telescope is a “super-mirror” that has a multi-layer coating to collect X-rays up to 80 keV. The other is a detector satellite that carries an SDCCD system. The SDCCD consists of a fully depleted CCD and a scintillator so that we can obtain the image up to 80 keV.