Sensitive far uv spectrograph with a multispectral element microchannel plate detector for rocket-borne astronomy

Abstract

An evacuated high transmission prism spectrograph using a microchannel plate detection system with resistive strip readout was flown behind a precision pointing telescope on a sounding rocket. The construction, preparation, flight performance, and calibration stability of the system are discussed. Despite the adverse environmental conditions associated with sounding rocket flights, the microchannel detector system performed well. Far uv spectra (1160–1750 Å) of stellar and planetary objects were obtained; spectral features with fluxes as low as 0.06 photons cm⁻² sec⁻¹ were detectable. This was achieved by operating the plates at lower than normal gains, using sensitive pulse counting electronics with both upper and lower limit discriminators, and maintaining the spectrograph and detector at a pressure of ~10⁻⁶ Torr until reaching altitude.