This
Astrobin Debut Object is a group of 4 tiny galaxies located in the constellation of Eridanus at a declination of -31 degrees.
The
Hickson catalog is a collection of 100 small galaxy clusters. The collection was published by Paul Hickson in 1982. A typical Hickson cluster has 4 galaxies, as in this case, but can have up to 7. I am not sure what Dr. Hickson was thinking here - there are many non-Hickson clusters out there which are much better than this one.
For debut objects, I often express surprised that they haven’t been imaged before on Astrobin. Not with this one. I almost gave up after 2 tries. I would like to see that the 3rd was the charm, but that is simply not the case. It is a difficult object to image. It sits at -31 degrees, which is tough to reach for those of us in the northern hemisphere. The galaxies are distant and appear tiny to us – the largest one is 15 arc-seconds long. Finally, they sit near a bright orange 3.8 magnitude star which is just off image to the left.
The magnitudes for galaxies 29a through 29d (annotation in the mouseover) range from 14.5 for the brightest galaxy (29a) down to 18.3 for the dimmest (29d). The brightest galaxy, 29a, is also by far the closest at 0.6 billion light years. 29a is an irregular galaxy and is 40,000 light years in diameter.
The other 3 galaxies – 29b, 29c and 29d – are all 1.5 billion light years away. It looks like b and d are spirals and c is an elliptical. The largest galaxy, 29b, is a Milky Way size of 120,000 light years in diameter.
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