This
Astrobin Debut Object is a group of 7 galaxies located 360 million light years away in the constellation of Leo at a declination of +24 degrees. 5 of these galaxies appear to be ellipticals and 2 appear to be spirals. The galaxies are all about the same distance away, but most of them do not show signs of interacting in my image so I assume that there is some spacing between them.
Hickson 51a, also known as NGC 3651, is the brightest and largest of the group. It is 1.1 arc-minutes in diameter, which corresponds to a Milky Way size diameter of 120,000 light years.
Hickson 51b, a spiral almost as large as 51a, has some interesting dust lane detail in its outer disk.
The most interesting galaxy is 51f, which appears to be distorted. Whether it is interacting with 51a is unclear.
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The Hickson catalog is a collection of 100 galaxy groups by Paul Hickson in 1982. Hickson compact galaxy groups are tightly spaced relative to other space objects. A typical Hickson group has 4 galaxies, but can have up to 8. The criteria for a Hickson Galaxy Group is specific and detailed in his paper, but basically it boils down to 3 simple things:
1. The group must have at least 4 galaxies, all with decent brightness;
2. The group must be isolated and not just part of a large cluster; and
3. The group has to be compact, with spacing between them similar to their sizes.
The galaxies are generally small, distant and a challenge to image. The diameter of a circle which surrounds each entire group ranges from 1 arc-minute to 16 arc-minutes. The brightest galaxy in each group is usually about magnitude 14.
My Hickson Collection is
here. I have now imaged 2/3 of the 100 Hickson galaxies.
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