title: Properties of a transmission grating behind a grazing incidence telescope for cosmic x-ray spectroscopy.
abstract: Third-order aberrations are discussed of a transmission grating positioned behind a Wolter type I telescope, using Fermat's principle. We describe the conditions required to obtain a coma-free grating. The performance of a grating spectrometer for cosmic x-ray spectroscopy is discussed in some detail.
authors.forename: K P
authors.initials: KP
authors.lastname: Beuermann
authors.forename: R
authors.initials: R
authors.lastname: Lenzen
authors.forename: H
authors.initials: H
authors.lastname: Bräuninger