The Collinder catalogue is a catalogue of 471 open clusters compiled by Swedish astronomer Per Collinder. It was published in 1931 as an appendix to Collinder's paper On structural properties of open galactic clusters and their spatial distribution.
Collinder 399, a prominent asterism in the constellation Vulpecula.
Brocchi's Cluster is a asterism of 10 stars. Six of the stars appear in an row, across 1.3° of the night sky. The cluster is in the south of the constellation Vulpecula, near the constellation Sagitta. Its nickname is the Coathanger. None of these ten stars are believed to be gravitationally bound to each other, thus they are not a star cluster, a fact established by the Hipparcos measurements 1997. An additional 30 or so much fainter stars are considered by some to be part of the asterism.
Amateur image of an asterism Collinder 399 and surroundings
The Coathanger (Cr 399); eight of its ten stars are labelled with at least their observed (apparent) magnitudes, as is the open cluster on the same alignment of the row of six (and centred with a similar angular separation to that of these stars) just east. The westernmost star has a smaller separation than the others.
