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S. Watchorn, F. L. Roesler (Dept. of Physics, U. Wisconsin - Madison), J. Harlander (Dept. of Physics, Astronomy and Engineering, St. Cloud State University), K. P. Jaehnig (Space Astronomy Laboratory, U. Wisconsin - Madison), W. T. Sanders (Dept. of Physics, U. Wisconsin - Madison), R. J. Reynolds (Dept. of Astronomy, U. Wisconsin - Madison)
This paper will report on the implementation of the field-widened Spatial Heterodyne Spectrometer (Harlander, J., Reynolds, R.J., & Roesler, F.L., 1992. ApJ, 396, 730) in its first field test, a sounding rocket flight to detect CIV emissions lines (near 155.0 nm) from the Cygnus Loop at high spectral resolution (20 km/s). The ultimate motivation for the development of this SHS is an all-sky, radial velocity-resolved map of the hot component of the diffuse interstellar medium (ISM). The large-scale dynamics and filling fraction of the hot ISM are not well understood, in part because there are no kinematic sky surveys of hot gas emission lines analogous to those of the cooler components of the ISM via CO, 21 cm, and H-alpha emissions. Such a survey of the hot component requires a spectrometer with sufficient etendue and spectral resolution to accomplish the mapping in a reasonable time. That spectrometer also needs to be compact and sturdy, to make it useful for space-based applications. The suitability of SHS in these areas will be described. The Cygnus Loop was chosen as an initial subject, principally, to test the efficacy of SHS in the field. Because the detected rate of CIV emissions from the Cygnus Loop was lower than expected, the SHS was not successful in providing a spectrum for those lines. However, thorough post-flight efficiency tests of the payload optics convincingly located the loss factor, indicating the problem was avoidable contamination, and not a fundamental failing of the SHS. The paper will conclude with the ways SHS was shown to be viable by this mission, and how it can be improved for continued studies of the Cygnus Loop and the hot diffuse ISM. We gratefully acknowledge the support of NASA for this project.
The author(s) of this abstract have provided an email address for comments about the abstract: watchorn@physics.wisc.edu