The development of the spatial heterodyne spectrometer for observations of C IV emissions near 1500 A from the cygnus loop and the diffuse hot interstellar medium.

摘要

There is little consensus about the nature of the diffuse hot interstellar medium (ISM), primarily because there has been no way to make an all-sky, radial velocity-resolved map of it analogous to the 21 cm observations of the cold ISM. The discovery of C IV λ1550 emissions from the hot ISM promise the possibility of such a map.; The Spatial Heterodyne Spectrometer is well suited to this purpose. It shares the advantages of conventional interferometers over slit spectrometers regarding high etendue and high resolving power. In addition, it has relaxed optical fabrication tolerances and no scanning mechanisms that could become misaligned on rocket launch. These aspects put it ahead of conventional interferometers for space-based applications.; In this dissertation, the basic concepts of SHS are described, shedding light on why it is a spatial-heterodyning Fourier Transform spectrometer. Its basic properties, such as resolving power, are elucidated, as well as important modifications like field widening.; The buildup of the SHS sounding rocket payload to study the Cygnus Loop—a supernova remnant whose bright C IV emissions have been previously characterized—is described. Considerations of payload design, component specifications and assembly are laid out, along with the buildup procedures for SHS, zero path alignment chief among them.; The results of the launch of the SHS payload to observe the Cygnus Loop are presented. First come important considerations regarding data analysis, followed by the results from flight. Those results show a count rate from the Cygnus Loop lower than expected by a factor of 17. Though the payload apparently detected the Cygnus Loop, no spectrum of its C IV emissions was obtained.; The final major section describes post-flight efficiency tests of the payload optics. These tests convincingly located the payload loss factor. A more careful assembly of the SHS payload—especially in limiting its exposure to air—combined with newly-developed cleaning techniques could make future SHS missions a complete success.