  The soft X-ray grating spectrometer on board the Off-plane Grating Rocket
Experiment (OGRE) hopes to achieve the highest resolution soft X-ray spectrum
of an astrophysical object when it is launched via suborbital rocket. Paramount
to the success of the spectrometer are the performance of the $>250$ reflection
gratings populating its reflection grating assembly. To test current grating
fabrication capabilities, a grating prototype for the payload was fabricated
via electron-beam lithography at The Pennsylvania State University's Materials
Research Institute and was subsequently tested for performance at Max Planck
Institute for Extraterrestrial Physics' PANTER X-ray Test Facility. Bayesian
modeling of the resulting data via Markov chain Monte Carlo (MCMC) sampling
indicated that the grating achieved the OGRE single-grating resolution
requirement of $R_{g}(\lambda/\Delta\lambda)>4500$ at the 94% confidence level.
The resulting $R_g$ posterior probability distribution suggests that this
confidence level is likely a conservative estimate though, since only a finite
$R_g$ parameter space was sampled and the model could not constrain the upper
bound of $R_g$ to less than infinity. Raytrace simulations of the system found
that the observed data can be reproduced with a grating performing at
$R_g=\infty$. It is therefore postulated that the behavior of the obtained
$R_g$ posterior probability distribution can be explained by a finite
measurement limit of the system and not a finite limit on $R_g$. Implications
of these results and improvements to the test setup are discussed.
