Xuv spectroscopic observation of the white dwarf star HZ 43

A soft x-ray objective grating spectrometer utilizing grazing incidence optics was designed for astronomical observations, assembled at Stanford, calibrated, and flown in 1983. The target was the hot white dwarf star HZ 43, which is of particular interest because it is one of the two brightest nonsolar extreme ultraviolet sources in the sky. The emission is thought to be thermal in origin, with an effective temperature of 60,000 degrees. The basic experimental configuration involved a confocal, coaxial pail of nested Woelter-Schwarzschild Type I telescopes, an annulus of free standing gold 500 I/mm transmission gratings, and a microchannel plate detector in the focal plane with proximity focused resistive anode readout. The telescopes were manufactured using the single diamond point turning technique at Lawrence Livermore National Lab. The point response function was measured in the visible. The angular size (full width at half maximum) was 25 arc seconds with a sharp central core of less than 5 arc second angular extent. The transmission gratings were supplied by the co-investigators at the Astronomical Institute of the Netherlands. The instrument as a whole was calibrated in a vacuum facility at U. C. Berkeley