Object of the Week, February 14, 2015: Arp 55 = VV 155 -- The Grasshopper

Arp 55 = VV 155 = UGC 4881 = MCG +08-17-065 = CGCG 238-025 = PGC 26132 = The Grasshopper
Interacting collision pair
RA: 09h 15m 55.1s Dec: +44° 19’ 55”
Size: 0.9'x0.8'
Mag: 14.0V, 14.9B
Surface Brightness: 13.5 mag/sq. arcmin

This remarkable interacting pair was first cataloged by Vorontsov-Velyaminov in his 1959 "Atlas and Catalog of Interacting Galaxies" and given the nickname "Grasshopper".

Here's the HST image from 2008
Arp 55 - HST.jpg

The caption reads "UGC 4881, known as the "The Grasshopper," is a stunning system consisting of two colliding galaxies. It has a bright curly tail containing a remarkable number of star clusters. The galaxies are thought to be halfway through a merger the cores of the parent galaxies are still clearly separated, but their disks are overlapping. A supernova exploded in this system in 1999 and astronomers believe that a vigorous burst of star formation may have just started. This notable object is located in the constellation of Lynx, some 500 million light-years away from Earth."

My first view was with my 18-inch Starmaster in 2010:
Arp 55 is faint, fairly small, slightly elongated E-W, 0.5'x0.4'. I occasionally noticed an extension (companion galaxy) or knot at the west edge. A couple of times it appeared resolved from the main glow as an extremely faint and small glow.

Needless to say, Jimi's scope provided a bit more detail in 2013:

Arp 55 = "Grasshopper" is a merger of two galaxies with a single tidal tail on the east side. At 488x it appeared bright, moderately large, very unusual appearance with a mottled main body elongated 2:1 SW-NE, ~30"x15". On the SW end is Arp 55S = PGC 3098124, a nearly stellar knot that is the nucleus of a merging, interacting companion. A faint, thin "arm" or "tail" is attached at the NE end and extends ~20"x5" straight south. The tail brightens slightly (perhaps an HII knot or another merged galaxy) at the south end. This knot has the designation SDSS J091556.72+441937.5. On the SDSS the tail curves sharply west on the south end, but this extension was not seen. A mag 16.2 star is 45" west.

SDSS J091559.93+442034.6 = PGC 2242096 lies 0.9' NE and appeared as a very faint (V = 17.1), very low surface brightness patch, 15" diameter. Arp called this object a "filament" of Arp 55 in his 1967 paper "Peculiar Galaxies and Radio Sources" (ApJ, 148, 321). PGC 82353 is 1.4' NE and appeared fairly faint, fairly small, slightly elongated E-W, 20"x15". PGC 2242434 lies 2.3' NW, just 27" W of a mag 14.7 star. It appeared fairly faint, fairly small, slightly elongated E-W, 20"x15". These three galaxies have a identical redshifts as Arp 55, so are part of a small group.

Here's a labeled SDSS image of these companion galaxies --
Arp 55 - Grasshopper.jpg

“GIVE IT A GO AND LET US KNOW”
GOOD LUCK AND GREAT VIEWING!