A Galaxy Group in Eridanus

A 15 minute exposure taken under poor sky conditions with STL-1301E CCD camera thru Kopernik's 20-inch F/8.1 telescope. The field of view is 15x13 arc minutes, with North at the top.

The negative version below has the galaxies identified and just begins to show the very dim outer arms of NGC 1723 and outer ring of NGC 1721.

All four galaxies have similar red shifts, but there is some difference. This might reflect relative motion inside the galaxy group, or they may not be all that close in space. However, two of the three in the close group have rather strange shapes, as does the fourth galaxy. NGC 1723 (top of Koperik image) is a little separated from the others. It has a theta shaped inner ring and bar, plus two very dim spiral arms, one of which is very spread out. (These arms just barely show in the Kopernik image.) NGC 1728 is a nearly edge-on Spiral Galaxy with a peculiar distorted shape. NGC 1721 is a Barred Spiral Galaxy with two very dim and narrow spiral arms that seem to form a pseudo outer ring (again, just barely seen in the Kopernik image). NGC 1725, the center galaxy of the triplet, is a Lenticular Galaxy. There is also one small dim background galaxy in the image.