Abstract
Since Hubble's discovery of the correlation between
galaxy radial velocity and distance, velocities of galaxies have
been obtained using slit spectra to establish the value of the Hubble
constant. More recently, with the acceptance of a general Hubble
flow, velocities have also been used to examine the distribution of
galaxies in space. Velocities within clusters of galaxies have also
been used to establish cluster velocity dispersions, and hence uirial
masses. Large numbers of galaxy velocities obtained over a small
area of sky to a faint limiting magnitude would help to construct a clearer picture of the medium scale (supercluster-sized) structure
of the Universe.
In this thesis the basis for a method of obtaining radial
velocities of faint galaxies from their objective prism spectra is
described. Measurement techniques, both manual and computer -based,
using digitised data from several measuring machines, are discussed.
The parameters able to affect the velocity measurement are examined,
and checks are made to compare velocities obtained from objective
prism spectra with velocities of the same objects obtained from slit
spectra. The method is shown to be easily applied to measurements of
individual known galaxies, but quite difficult to apply to large numbers
of objects using computer techniques. In particular the signal to
noise ratio in galaxy spectra has a very important effect on automated
velocity measurements.
elocity measurements.
The application of the method to clusters of galaxies is demonstrated,
and preliminary results presented for several Abell clusters.
The application of the method to the general field is discussed, and
the problems encountered with this application described. It is
concluded that the technique described has great potential for both
the study of clusters of galaxies, and if certain measurement problems
can be overcome, for the study of the distribution of galaxies in large
volumes of space.