Gary Imm



A backyard amateur astrophotographer enjoying retirement with my wife on beautiful Lake Livingston in Onalaska, Texas, about 90 minutes north of Houston.

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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. The objects below are listed in order of their Hickson number.