Development of a spatial heterodyne spectrometer and associated instrumentation for space and ground observatories

Abstract

We describe the development of compact, lightweight payloads suitable for ground, space, and balloon-based observatories. The first instrument is

a compact high resolution (≥ 20000) tunable spatial heterodyne spectrom- eter (TSHS). Spatial Heterodyne Spectroscopy (SHS) is a relatively novel

interferometric technique similar to the Fourier transform spectroscopy with heritage from the Michelson Interferometer. An imaging detector is used at

the output of an SHS to record the spatially-heterodyned interference pat- tern. The spectrum of the source is obtained by Fourier transforming the

recorded interferogram. Since these instruments do not have slits, the entire incoming beam can be used to generate the spectrum. The small bandwidth

limitation of the SHS can be overcome by building it in a tunable config- uration (TSHS). This instrument can be used to observe and study faint,

extended emission line targets by retrieving the high-resolution spectra from the entire source. The second instrument is a pointing system suitable for balloon mission. Our first balloon observations were of atmospheric lines where the pointing stability is less critical, but now we are observing astronomical sources for which a pointing mechanism is required. Hence, in this work, we describe the design and realization of a low-cost light-weight 2-axis correction pointing and stabilization system intended for use in small balloon flights, built entirely using off-the-shelf components with an accuracy of 0.5 degrees.