Performance of the repolished S-056 grazing incidence mirror in the MSFC AXAF test facility

The S-056 Wolter I soft x-ray mirror used originally on Skylab for x-ray observations of the Sun is still in use today. The mirror has been flow polished to a surface finish of 5 angstroms for spatial frequencies from 1 - 1000 mm-1 and has been tested in the AXAF x- ray calibration facility located at Marshall Space Flight Center, Alabama. The mirror performance was enhanced by a new polishing technique and was found to have an experimental point spread function full width half maximum of less than 1 arc second at 8.3 angstroms. No change in the figure was observed.