Object name: ARP315

Designation(s): ARP315, ABELL0779, NGC2825, NGC2826, NGC2827, NGC2829, NGC2830, NGC2831, NGC2832, NGC2834, NGC2839,

Arp 315/Abell 779 is a group of galaxies in southern Lynx. Arp 315 is just 3 of the 83 galaxies in the Abell 779 galaxy cluster that mark the heart and is likely the anchor of the group. Arp put them in his Group of Galaxies category. The three in his atlas are NGC 2830, NGC 2831 and NGC 2832 right to left. They don\'t appear to be interacting so are likely further apart than our perspective makes it appear. His comment reads: \"Companion E [NGC 2831] is quite compact.\"

The group is about 300 million light-years from us. NGC 2832 dominates the group. It is obviously a cD galaxy (\"central Dominant), also under Yerkes galaxy classification, it means by the c that it is a super giant galaxy and the D that it is diffuse (elliptical), galaxy. NED classes it as E2+2 while the NGC project says E4. NGC 2831 is classed as E0 by both. NGC 2830 is simply S under the NGC Project and SB0/a: per NED. It appears to be nearly edge on.

NGC 2825 was discovered on April 3, 1831 by John Herschel
NGC 2826, 2831 and 2832 were discovered on March 13, 1850 by George Stoney
NGC 2830 was discovered by William Herschel on December 7, 1875 but isn\'t in either H400 program

I\'ve prepared an annotated image that shows both the catalog entry and redshift distance per NED using 5 year WMAP data. There is quite a spread likely indicating rather high orbital velocities of the galaxies in the group. Including the identification rather than just the distance greatly increased the file size as well as making it hard to put in labels without overwriting other objects. If the object isn\'t a member of the group I only show its nature (Q-quasar, G-galaxy) and distance. Those without a label had no distance data in NED so I couldn\'t determine if it was a cluster member or not. A few weren\'t in NED\'s database. I noted one of these, a rather bright one, with a question mark. Why these don\'t make the catalog is still a mystery to me. No one seems to know the answer, at least no one has told me.

Looking around the image there are a lot of galaxy pairs and triples, many of which appear to be interacting others just line of sight pairs. There\'s a lot going on all over this image if you go looking for it.

There\'s one asteroid in the image, (230947) 2004 XY54 at magnitude 18.5

Arp\'s image
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp315.jpeg

14\" LX200R @ f/10, L=4x10\' RGB=2x10\'x3, STL-11000XM, Paramount ME