SIXE: An X-ray experiment for the MINISAT platform

Abstract

SIXE (Spanish Italian X-ray Experiment) is an X-ray payload with geometric area of ~3200 cm2 , formed by four identical gas-filled Multiwire Proportional Counters devoted for a long term spectroscopy of selected X-ray sources in the energy range ~3-60 KeV. The spectral resolution of ~5% for E>35 KeV and ?E/E=60/E1/2 for E<35 KeV, the continuum sensitivity (3o in 105 s) of ~3•10-6ph/cm2 •KeV, the line detection sensitivity (3o in 105 s) of ~3.5•10-6ph /cm2 •KeV, the time accuracy of 0.1 ms, the experiment weight of ~90 Kg, the full dimensions including the electronic box of ~660x660x400 mm3, the power budget of -40 W, the telemetry rate of :=100 Kbit/s and on-board memory of ~2 Gbytes makes this experiment fully compatible for a minisatellite mission, such as for istance the spanish MINISAT 02. The main scientific goal of SIXE is the study of the short and long term spectral and intensity variabilities of few selected extragalactic and galactic X-ray sources, such as quasars, Seyfert galaxies, high and low mass X-ray binaries, etc. Since the sensitivity and the energy resolution of SIXE are rather good, it is possible to study the behaviour of the eventual Fe lines with respect to the continuum emission. This possibility of SIXE is unique for the present generation of X-ray experiments, since no one is dedicated to long term monitoring of X-ray sources.