Review of Spectroscopic & Spatial Observations of Cometary Comae

Abstract

During the past few years the field of comet spectroscopy has greatly expanded with observations of comets having nuclear magnitudes in the range of 10-19th magnitude. Although the total integrated magnitudes of several of the comets were brighter than 10th magnitude, the surface brightness of the coma of a comet is low and, with few exceptions, the night sky line at 5577A is brighter than any cometary emission line. The observational programs on which I will concentrate had their start under the P/Tempel 2 and P/Encke observing programs set up by R. Newburn at JPL.Fortunately, the groups listed in Table 1 are regularly scheduled on large telescopes to observe comets. The regularly scheduled telescope time has enabled these groups to study systematically the activity of the available comets brighter than 20th magnitude. Observations have been made with respect to heliocentric distance and distance from the nucleus. The goal of the systematic study of comets is to acquire a uniform data set on comets. The great variety of comet spectra in the past did not provide a useful data base for statistical studies. These older observations ranged from high resolution spectra of brighter comets, to sporadic medium and low resolution spectra and filter photometry of the 10th magnitude comets, to nonexistent spectra of fainter comets.