The microcalorimeter spectrometer on the ASTRO-E X-ray observatory

The Astro-E Observatory will employ a high-resolution X-ray spectrometer based on a 32 pixel array of microcalorimeters with an energy resolution of about 12 eV at 6 keV (the Fe-K region). This will provide spectral resolving power 10 times higher than any other non-dispersive X-ray spectrometer. The instrument incorporates a three-stage cooling system capable of maintaining the temperature of the detector stage at 60 mK for about two years in orbit with a 97% duty cycle. The array sits at the focus of a grazing incidence conical mirror. The quantum efficiency of the microcalorimeters and the reflectivity of the X-ray mirror system combine to give high throughput over the 0.3-12 keV energy band. This new capability will enable the study of a wide range of high-energy astrophysical sources with unprecedented spectral sensitivity