Bragg imaging of extended cosmic x-ray sources: the objective crystal spectrometer.

A need exists for a high resolution (E/DeltaE greater, similar 500-1000), imaging (~5 x 5 arcmin pixel) spectrometer capable of studying cosmic x-ray sources with appreciable angular extent (up to 1-2 degrees ) and which emit a broad range of line spectra from highly ionized plasmas (oxygen through iron). A large flat objective crystal couples nicely to a modest resolution but high throughput x-ray concentrating telescope to produce high dispersion images of diffuse x-ray sources in each of the several lines present in the spectrum. Unprecedented spectral resolution is provided for point sources and, provided that they do not vary on rapid time scales, a spectrum can be scanned over a wide energy range with unparalleled sensitivity.