What is Arp?

Already in 1966 Dr. Halton C. Arp compiled his "Atlas of Peculiar Galaxies" of 338 unusual galaxies, interacting pairs or larger groups. His work was supported with photographs taken with the Palomar 200-inch telescope. The catalog classifies the galaxies into 6 large classes that represent the major peculiarities. These are listed left. Additionally Arp introduced further 39 subclasses, which should describe the characteristics of the galaxies more precisely.

This page presents a collection of the 100 most beautiful and most interesting galaxies of the Arp catalog and of their observations. The list covers galaxies, their irregularities and a group character, which should be observable in mid-sized or large amateur telescopes. So they are attractive targets for many amateur astronomers, both visual and photographic, off the well-known objects in the sky. The observations and drawings of the 100 selected Arp galaxies were collected by Martin Schoenball, Uwe Glahn and Matthias Juchert and were made with telescopes of 2.5"-24" aperture. On the following pages the observations already made are presented. They should give some inspiration for planning own observations and take up new object ideas. Active observers, who want to join the project, are welcomed! For a quick overview of the 100 objects a list and a photographic overview are available.

Martin Schoenball
Matthias Juchert
Uwe Glahn