Object name: ARP112

Designation(s): ARP112, NGC7805, NGC7806,

Arp 112 is a triple galaxy group classed by Arp as "Elliptical and elliptical-like galaxies with repelling arms." How that applies to this weird group I don't know. Maybe it is due to the near vertical spike coming from the northeastern galaxy. I placed Arp 112 well to the right of center to pick up another rather odd galaxy at the left hiding behind a star. It is PGC 000190 and is classed as an S0? galaxy. This seems very wrong. S0 galaxies have no or very weak spiral structure and usually appear as round spheres or spindle-like depending on our viewing angle. This looks like a rather nice face on Sb spiral with rather well-defined arms. I don't understand the discrepancy.

Arp 112's trio of galaxies from left to right is KUG 2359+311/PGC 111 with no redshift data. KUG stands for Kiso Ultraviolet Galaxy Catalogue indicating it is a strong emitter of ultraviolet light. Usually a sign of massive star formation. It looks like an arc but is classed simply as a spiral galaxy, not even a peculiar one. Sure looks peculiar to me. The center galaxy is NGC 7806 with a redshift distance of 200 million light years and is classed as SA(rs)bc? Pec. While tidally distorted it doesn't appear as peculiar as its companion to the east. The class indicates it has structures of both a standard spiral and a ring galaxy. Apparently, the ring refers to the outer football shaped bright edge around a portion of the galaxy. The rightmost galaxy is NGC 7805 also at about 200 million light years per its redshift. It is classed as SAB0 pec but has no ring designation yet one is quite prominent in my image. That I do find as peculiar. Its class would indicate it has elements of a standard spiral and a barred spiral with little dust or arm structure. Hence Arp's elliptical like reference. It also has the color of an elliptical as well.

NGC 7805 and 7806 were discovered by William Herschel on October 9, 1790. Neither are in either of the two Herschel 400 observing programs, however.

Nearly all the other galaxies are either anonymous or have little data. The only one worth mentioning is the blue galaxy southwest of Arp 112. It has the rather rare designation NPM1G +31.0507. This comes from the Lick "Northern Proper Motion program 1st list of Galaxies. Don't ask, I never heard of it either. Arp 112 is located in Pegasus not far from Arp 98 and 2.75 degrees northwest of Alpha Andromedae, Alphoratz, the lower left corner star of the "Great Square of Pegasus".

Arp's photo of it is at

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