RA 23.4968° · Dec 30.5674° · openngc
6 more points to reach Uncommon.
IC 139 is a common cluster. It sits in the constellation Tri and shines at apparent magnitude 13.1.
A stellar association: a sprawling family of hot young stars that shared a birthplace but were never gravitationally bound to each other.
Look for IC 139 in the constellation Tri. At apparent magnitude 13.1, it takes a larger telescope or a long-exposure image to capture.
Like any astronomical target, IC 139 is best seen from a dark site away from city lights, and when it is above the horizon depends on your latitude and the time of year. The visibility panel above works out tonight's viewing window for your saved location.
IC 139 scores 16 points on Spacedle's rarity scale, which places it in the common tier. Another 6 points would lift it into a rarer tier.
That score comes from 3 science badges — Star cluster, Loose stellar association and Faint fuzzy (mag > 13) — each earned for a real, measurable property of the object. Rarity on Spacedle is never random: the more remarkable an object's astrophysics, the more badges it collects, the higher it scores, and the rarer it ranks.