The Bragg Crystal Spectrometer for AXAF

MIT's High Resolution X-ray Spectroscopy investigation on AXkF involves two complementary dispersive instruments, a Bragg Crystal Spectrometer (BCS) and a High Energy Transmission Grating Spectrometer (HETGS). The overall goal of the investigation is to study the physical condtions in celestial sources by means of detailed measurements of their X-ray spectra. High spectral resolution measurements can be used to perform diagnostics of emitting and absorbing matter, leading to knowledge of temperature, ionization state, elemental abundance, density and optical depth.