The targets for the Hubble Telescope 35th Anniversary Challenge were a diverse range of objects.
The first up is my favorite planetary nebula – the Helix Nebula (NGC 7293 or Caldwell 63). Although not quite as easy to photograph as the Dumbbell Nebula, I like the circular form and range of colors in the Helix. The object is a planetary nebula located in the constellation Aquarius. Discovered by Karl Ludwig Harding, most likely before 1824, this object is one of the closest of all the bright planetary nebulae to Earth. The distance is 655±13 light-years from Earth. It is similar in appearance to the Cat’s Eye Nebula and the Ring Nebula, whose size, age, and physical characteristics are in turn similar to the Dumbbell Nebula, differing only in their relative proximity and the appearance from the equatorial viewing angle. The Helix Nebula has sometimes been referred to as the “Eye of God” in pop culture, as well as the “Eye of Sauron”.
Messier 30 (also known as M30, NGC 7099, or the Jellyfish Cluster) is a pretty globular cluster of stars in the constellation of Capricornus. It was discovered by the French astronomer Charles Messier in 1764, who described it as a circular nebula without a star. In the New General Catalogue, compiled during the 1880s, it was described as a “remarkable globular, bright, large, slightly oval.” It can be easily viewed with a pair of 10×50 binoculars, forming a patch of hazy light some 4 arcminutes wide that is slightly elongated along the east–west axis.
Messier 2 or M2 (also designated NGC 7089) is also a globular cluster, but in the constellation Aquarius, five degrees north of the star Beta Aquarii. It was discovered by Jean-Dominique Maraldi in 1746, and is one of the largest known globular clusters. M2 was discovered by the French astronomer Jean-Dominique Maraldi in 1746 while observing a comet with Jacques Cassini. Charles Messier rediscovered it in 1760, but thought that it is a nebula without any stars associated with it. William Herschel, in 1783, was the first to resolve individual stars in the cluster. M2 is, under extremely good conditions, just visible to the naked eye. Binoculars or a small telescope will identify this cluster as non-stellar, while larger telescopes will resolve individual stars, of which the brightest are of apparent magnitude 6.5.
NGC 7814 (also known as Caldwell 43) is a spiral galaxy about 40 million light-years away in the constellation Pegasus. The galaxy is seen edge-on from Earth. It is sometimes referred to as “the little sombrero”, a miniature version of Messier 104. The star field behind NGC 7814 is known for its density of faint, remote galaxies as can be seen in the vicinity of this object, in the same vein as the Hubble Deep Field.
It’s among the few bright galaxies that exhibit modest distortion and twisting of the galaxy’s plane in optical wavelengths. The light from the distant background galaxies becomes more red as it passes through NGC 7814’s halo. This has been used to determine the amount of gas and dust in the halo. One supernova has been observed in NGC 7814: SN 2021rhu (Type Ia, mag 15.66) was discovered by Automatic Learning for the Rapid Classification of Events (ALeRCE) on 1 July 2021.
NGC 7662 is a planetary nebula located in the northern constellation Andromeda. It is known as the Blue Snowball Nebula, Snowball Nebula, and Caldwell 22. This nebula was discovered October 6, 1784 by the German-born English astronomer William Herschel. In the New General Catalogue it is described as a “magnificent planetary or annular nebula, very bright, pretty small in angular size, round, blue, variable nucleus”. The object has an apparent visual magnitude of 8.3. Parallax measurements give a distance estimate of 5,730 ± 340 ly (1,757 ± 103 pc). NGC 7662 is a popular planetary nebula for casual observers. A small telescope will reveal a star-like object with slight nebulosity. A 6″ telescope with a magnification around 100x will reveal a slightly bluish disk.
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