Classification of comets from new methods for spectroscopy of gas and dust

This dissertation presents results of a program of comet long-slit spectroscopy with the Kast Dual Spectrograph on the 3-m Shane Telescope at Lick Observatory. Coma gas production rates for OH, CN, C2, C3, NH, and NH2 are calculated from Haser (1957) model fits to the data of 26 different comets, from a variety of dynamical families, observed on 40 different nights. New techniques for long-slit data reduction and Haser model fitting are being employed systematically for the first time. Active comets commonly appear close to the Sun, where the rapidly changing twilight sky resists the usual employment of separate sky frames for sky subtraction of the comet frames. Thus, we have developed a statistical method for subtracting the twilight sky within such extreme comet frames themselves. A method introduced by Fray et al. (2005) is used to find Haser model scale lengths and their uncertainties. Unbiased testing of a range of parent- and daughter-species scale lengths reveals the best-fitting scale length pairs, which are compared with scale lengths found in the literature. Our longslit spectroscopy data is adapted for the A(theta)frho dust production parameter introduced by A'Hearn et al. (1984). The total comet survey improves our understanding of the diversity among comets, including unusual comets such as 96P/Machholz.