Basic problems in the photographic photometry of nebulae

Abstract

This thesis is concerned with problems which arise in photographic surface photometry using the Cassegrain Schmidt Telescopes at the University Observatory, St Andrews. Photometric investigations are made of different types of objects with telescopes of different apertures and focal lengths, but with approximately the same focal ratios, in order to study the photometric effects in different types of surface distributions and to assess critically the effect of resolution on the photometry. Basic to the problem is the question of the photographic process with its inherent difficulties and limitations. For this reason, detailed consideration is given to those aspects of the process which are particularly relevant to the problem of extended surface photometry. The question of the effect of resolution arose naturally in the course of the investigation when it was possible to extend the observational programme from the 17-inch to the 37-inch telescope when it was commissioned for observational work. This thesis does not aim to obtain a comprehensive set of parameters to describe the surface distributions of a large number of objects, nor to make theoretical deductions from the data, as the emphasis in the work is primarily on basic problems in surface photometry and techniques of data reduction.