Collinder 66

Collinder 66 is a small, compact open star cluster in the constellation Auriga, also known as Cr 66 and NGC 1907. It sits close to the better-known Messier 38 (the Starfish Cluster). It is about 5,800 light-years away and has a radius of about 6 arcminutes, with only a few dozen stars easily visible in amateur telescopes. It stands out for its closeness to M38, only about 34 arcminutes to the south-southwest, but the two clusters are not related. NGC 1907 is farther away and about twice as old, around 400 million years versus 200 to 290 million years for M38. One analysis suggests they formed in different parts of the Galaxy and are now making a celestial “fly-by”. Some faint nebulosity (Hα and a small reflection nebula) is present around it, though it is rarely seen in images. At magnitude 8.2 it is a telescope target