Brocchi's Cluster

Collinder 399 ( Cr 399 short ) or Brocchi is a bunch asterism ( a random array of physically nonbonded objects) of stars of the 5th to 7th class size and is located in the constellation Vulpecula. The geometric impression of the brighter individual stars is the reason for the common name hangers or hanger heap. With the naked eye, a diffuse spot can be seen with binoculars or a small telescope can recognize the characteristic shape. The asterism was formerly thought to be an open cluster, but this could be excluded using data from Hipparcos.

The expansion of the asterism is about 1 °. The brightest star of the cluster is 4 Vul with a brightness of 5.2 like the overall brightness is about 3.6 mag.

The group was mentioned in the literature for the first time by Al Sufi in the year 964, but is not included in the modern standard catalogs Messier, NGC and IC. Per Collinder the group took in 1931 in his catalog of open cluster on.