The Atlas of Peculiar Galaxies is a catalog of peculiar galaxies compiled by Halton Arp in 1966.
A total of 338 galaxies are presented in the atlas, which was originally published in 1966 by the
California Institute of Technology.
Mt. Palomar Hale Telescope **2
Only a handful of decades before 1966 it was not universally understood that “nebulous” galaxies existed
beyond the bounds of our Milk Way galaxy. Arp assembled his catalog from photographic sky surveys performed
on the Hale telescope at Mt. Palomar and other deep sky surveys to provide a set of example galaxies
for astronomers to study in order to propose/debate theories on the nature of galaxies and how they might form.
Halton Arp was a controversial figure in the astronomy/cosmology world and disagreed with a number of
the theoretical conclusions from this galactic debate. For instance, today it is accepted that many of
the sky survey photos in his catalog are of galaxies colliding or gravitationally interacting with each
other whereas Arp’s conclusion was that they were galaxies expelling populations of stars to form new galaxies.
General categories of galaxies in the Arp Catalog
Objects 1-101 are “conventional” spiral galaxies, some with apparent companions
Objects 102- 145 are elliptical shaped galaxies.
Objects 146-268 are galaxies that a neither elliptical nor spiral in shape.
Objects 269 - 327 are double galaxies.
Objects 332 - 338 are very peculiar galaxies which do not easily fit into the above categories.
The groupings above are very general. Halton Arp’s catalog listed many more specific categorizations which you can investigate by clicking on the links below.
