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[173.19] Use of a Near UV Spatial Heterodyne Spectrometer for Interstellar [OII] Emission Line Studies: Characteristics, Calibration, and Atmospheric Foreground Characterization

D. W. Fallest (Beloit College), E. J. Mierkiewicz, F. L. Roesler (University of Wisconsin - Madison), J. M. Harlander (St. Cloud State University), R. J. Reynolds, K. P. Jaehnig (University of Wisconsin - Madison)

This paper describes the use of a newly developed Spatial Heterodyne Spectrometer (SHS) designed to observe radial velocity resolved profiles of diffuse [OII] 3726 Å\ and 3729 Å\ emission lines from the warm (10⁴ K), low-density (10^-1 cm^-3), ionized component of our Galaxy's interstellar medium (WIM). The [OII] SHS combines interferometric and field-widening gains to achieve sensitivities much larger than conventional grating instruments of similar size and resolving power, and comparable to the Wisconsin H\alpha Mapper (WHAM) Fabry-Perot, but in the near UV where WHAM cannot observe. The high spectral resolution and sensitivity of the SHS allowed us to spectrally isolate for the first time Galactic from terrestrial [OII] emission. We were able to identify the terrestrial [OII] foreground emission and other nearby airglow lines in directions toward very low intensity Galactic [OII] emission regions. The terrestrial [OII] \lambda3729/\lambda3726 line intensity ratio was measured to be 0.47 ±.05:1, compared to an emission ratio of 1.5:1 predicted (and observed) for the interstellar [OII] emission lines in the low density limit. Atmospheric foreground characterization, spectral calibration and absolute intensity calibration are discussed.

This research was supported by the NSF through an Astronomy and Astrophysics REU site grant (AST-0453442) at UW-Madison.

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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.