Halton Christian "Chip" Arp was an American astronomer. He is remembered for his 1966 book Atlas of Peculiar Galaxies, which catalogued unusual looking galaxies and presented their images.
Halton Arp in London, October 2000
Halton Arp (right) and his grandsons, 2008
Arp 230, also known as IC 51, observed by the NASA/ESA Hubble Space Telescope.
Atlas of Peculiar Galaxies
The Atlas of Peculiar Galaxies is a catalog of peculiar galaxies produced 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. The primary goal of the catalog was to present photographs of examples of the different kinds of peculiar structures found among galaxies.
The Antennae Galaxies (Arp 244)
Colliding spiral galaxy pair NGC 3808A and NGC 3808B (Arp 87).
NGC 6621/NGC 6622 (Arp 81), a pair of spiral galaxies 100 million years after their colliding.
IC 883 (Arp 193), remnant of two galaxies' merger.