We present here preliminary results of the ASCA satellite. ASCA is equipped with X-ray telescopes that can observe the energy range up to 12 keV. There are two types of detector systems: GIS and SIS. The energy resolution of the SIS is 130 eV (FWHM at 7 keV) and can resolve emission lines clearly. For the PV phase, we planned to observe about 150 sources. Among them, there are 23 SNR's, some of which are presented here. We will be able to study the evolution of thin hot plasma in the SNRs.

Introduction

The fourth Japanese X-ray Astronomy satellite was successfully launched on February 20, 1993, from Kagoshima Space Center. The satellite's pre-launch name, Astro-D, was changed to it ASCA once it achieved orbit. ASCA is equipped with four thin foil X-ray mirror telescopes (XRT) that can collect X-rays up to 12 keV. Fig. 1 shows the effective area of the XRT. The XRT has a point spread function (PSF) with a half power diameter (HPD) about 2.7 arcmin. There is a sharp core of about 20 arcsec diameter in the PSF that enables us to separate point sources separated by less than one arcmin.

ASCA has two types of detectors: one is the imaging gas scintillation proportional counter, (IGSPC, Ohashi et al, 1991) and the other is the X-ray CCD camera (Burke, et al., 1993). They are called the gas imaging spectrometers (GIS) and the solid-state imaging spectrometers (SIS), respectively.