Spectroscopic observations of comet Austin (1989c)

Longslit CCD spectra (lambda = 5100-6400 A, delta(lambda) approximately 3 A) were obtained with the Michigan-Dartmouth-MIT 1.3 meter telescope in May 1990 (r = 0.74 AU, delta = 0.50 AU). The spectra were reduced with the Interactive data Reduction and Analysis Facility (IRAF). Spectral extractions offset sunward and tailward from the nucleus were analyzed. Species identified in the spectra include the following: C2, NH2(10-0), NH2(9-0), H2O(+), and CO(+). Spatial extractions of rotational line intensities in the NH2(10-0) band extend approximately 10(exp 4.5) km from the nucleus. A fit of the vectorial model to the NH2(10-0) spatial profile is consistent with an NH3 parent molecule. The NH2 production rate and an ammonia to water abundance ratio, NH3/H2O approximately 3 percent, were derived. The ammonia abundance obtained for comet Austin is consistent with that found for several other comets and is indicative of comet formation under very homogeneous conditions.