An updated optical design of the off-plane grating rocket experiment

The Off-plane Grating Rocket Experiment (OGRE) is a soft X-ray spectroscopy suborbital rocket payload designed to obtain the highest-resolution soft X-ray spectrum of Capella to date. With a spectral resolution goal of R(λ/uλ) < 2000 at select wavelengths in its 10-55 A bandpass of interest, the payload will be able to study the line-dominated spectrum of Capella in unprecedented detail. To achieve this performance goal, the payload will employ three key technologies: mono-crystalline silicon X-ray mirrors developed at NASA Goddard Space Flight Center, reflection gratings manufactured at The Pennsylvania State University, and electron-multiplying CCDs developed by The Open University and XCAM Ltd. In this document, an updated optical design that can achieve the performance goal of the OGRE spectrometer and a new grating alignment concept to realize this optical design are described.