"Arp" galaxies can roughly be described as galaxies with some abnormality or peculiarity. Dr. Halton Arp (1927 - 2013) compiled the original Arp Atlas with photographs he made mainly using the Palomar 200-inch telescope and the 48-inch Schmidt between the years of 1961 and 1966. The Atlas was published in the Astrophysical Journal Supplement Number 123, Volume 14, November 1966, University of Chicago Press. A small number of larger scale photographic prints of the Atlas were published in 1966 and 1978. There are 338 individual Arp galaxies, the fields ranging from familiar bright galaxies like M51 down to faint 17th magnitude nearly-anonymous spots. Few star charts or observing guides reference the Arp number, so to find most Arps, the observer must start with a reference which relates more commonly used galaxy names to the Arp number.
In order to help CCD imagers and observers with their work, a publication from Willman-Bell has catalogued some of the best available current information on these objects. Many of our images appear in this publication, and we are honoured to feature alongside other imagers and observers whose work we respect and admire. Our own Arp crusade started when we realised that these objects can present some of the more interesting sights in the sky. Although some of them are so tiny that it is really tough to see the object, let alone any peculiar aspect, in our opinion the crusade has been well worth the hours devoted to it. As you can see, our catalogue is complete, but some of the images are poor and we are continually working to improve the list as our techniques and equipment improve and the skies permit. Hopefully, in these pages you will find that for which you are looking. We have divided the galaxies into groups to ease browsing. Click on the link which contains the number for which you are looking.