The Atlas of Peculiar Galaxies is a Astronomical catalog.
In it, 338 unusual galaxies are listed with photographic images.
History
The catalog was compiled by Halton Arp in the 1960s and published in 1966.
Therefore it is also called Arp catalog.
Arp sought in own work and lists of other astronomers for galaxies unusual appearance.
He took for each object using the 5 -meter telescope at the Mount Palomar Observatory under good observing conditions a photograph in the blue spectral range.
Arp divided his catalog of unusual galaxies on purely morphological criteria in groups ( See Appendix ).
Importance
The Arp catalog was the starting point of many detailed studies of unusual and interacting galaxies, even if the specific morphological classifications and some underlying model concepts Arps today often less importance is attached to.
As a shortcut Arp or APG will be used.
The elements of the catalog
Spiral galaxies with low surface brightness (1-6)
Spiral galaxies with split arms ( 7-12)
Spiral galaxies with separated sections ( 13-18)
Three-armed spiral galaxies (19-21)
One-armed spiral galaxies (22-24)
Spiral galaxies with a strong arm (25-30 )
Spiral galaxies with the form of an integral character ( 31-36)
Spiral galaxies with a companion low surface brightness on one arm ( 37-48 )
Spiral galaxies with a small companion high surface brightness on one arm ( 49-78 )
Spiral galaxies with a large high surface brightness companion on one arm ( 79-91 )
Spiral galaxies with an elliptical companion on an arm ( 92-101 )
Elliptical galaxies with connection to spirals ( 102-108 )
Elliptical galaxies, the spiral arms repel ( 109-112 )
Elliptical galaxies nearby spiral galaxies and these disturbing ( 113-132 )
Elliptical galaxies with near fragments ( 133-136 )
Elliptical galaxies with outflowing material ( 137-145 )
Galaxies with associated rings ( 146-148 )
Galaxies with jets ( 149-152 )
Disturbed galaxies with internal absorption ( 153-160 )
Galaxies with diffuse filaments ( 161-166 )
Galaxies with diffuse counter- poor ( 167-172 )
Galaxies with narrow counter- poor ( 173-178 )
Galaxies with narrow filaments ( 179-193 )
Galaxies with out spin-coated from nuclear matter ( 194-208 )
Galaxies with irregularities, absorption and resolution ( 209-214 )
Galaxies with adjacent loops ( 215-220 )
Galaxies with amorphous spiral arms ( 221-226 )
Galaxies with concentric rings ( 227-231 )
Galaxies with signs of splitting ( 233-256 )
Galaxies with irregular clumps ( 257-268 )
Double galaxies with associated poor ( 269-274 )
Interacting double galaxies ( 275-280 )
Double galaxies with inflow and attraction ( 281-286 )
Galaxies with wind effects ( 287-292 )
Galaxies with long filaments ( 294-297 )
Unclassified objects ( 298-310 )
Groups of galaxies ( 311-321 )
Chains of galaxies ( 322-332 )
Various ( 333-338 )
