Collinder 36

Collinder 36 is an open star cluster in the constellation Cassiopeia, also known as Cr 36, Trumpler 3 and Harvard 1. It is a small, poor, low-contrast group of stars about 2,200 to 2,250 light-years away (roughly 690 parsecs), though older studies give as little as 450 parsecs. It is a fairly loose cluster, spanning roughly 14 to 17 arcminutes. It stands out as a tight little swarm of stars cupped inside a curving arc of brighter stars, "like sugar in a spoon" in the words of Sky & Telescope. It is relatively young: estimates range from about 70 million to 220 million years, depending on the study. At magnitude 7.0 it is a decent target for small telescopes. It lies about 3° northeast of the Heart Nebula region, and its two brightest stars are only around magnitude 10.