The Sax Mission for X-Ray Astronomy

Abstract

The satellite for X-ray astronomy SAX, to be launched at the end of 1993, is devoted to systematic, integrated and comprehensive, studies of galactic and extra-galactic sources in the energy band 0.1–200 keV, and is under joint development by the Italian Space Agency (ASI) and the Netherlands Agency for Aerospace programs (NIVR), with the participation of SRU/SRON and SSD/ESTEC. The basic scientific objectives can be summarized as follows:

• — Broad band spectroscopy (E/△ E=12) from 0.1–10 keV with imaging resolution of 1 arcmin.

• — Continuum and line spectroscopy (E/△ E=5-20) in the energy range 3–200 keV.

• — Variability studies of bright source energy spectra on timescales from milliseconds to days and months.

• — Systematic long term variability studies over the entire sky down to a source intensity of 1 mCrab.

The payload consists of four concentrator/spectrometers (3 units 1–10 keV, 1 unit 0.1–10 keV, for a total effective area of 200 cm² at 7 keV), a high pressure gas scintillation counter (3–120 keV, effective area of 300 cm² at 6 keV), a phoswich scintillation counter (15–200 keV, effective area of 600 cm² at 60 keV) which are all coaligned, and is completed by two wide field cameras (2–30 keV, 20deg × 20deg FWHM, and effective area of 250 cm2, pointing orthogonally with respect to the other instruments.

The three axis stabilised satellite will be placed into a circular orbit at 600 km with inclinatiobn of two degrees by an Atlas G-Centaur. The minimum mission lifetime will be two years but extendable upto four years.