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Coathanger

Binoculars • Special Asterisms Coathanger finder map.

Finder map for Coathanger

A famous and beloved target for amateur astronomers, often one of the first objects shown to beginners due to its clear and recognizable shape in binoculars. Best observed when high in the sky to maximize contrast and minimize atmospheric extinction. Well placed for Northern Hemisphere observers during summer and early autumn. The main challenge is framing the entire object, as it is too large for most telescope eyepieces at typical magnifications.

Coathanger finder optic view.

Finder scope & binocular view of Coathanger

PropertyValue
Common namesBrocchi’s Cluster, Al-Sufi’s Cluster
Catalog namesCr 399
TypeStellar Cluster
Subtype-
Coordinates19h 25m 23.9s, +20° 11’ 13.5”
SeasonJune - August
Best monthMid-July
Beginner friendlyYes
Visual rewardHigh
Filters requiredNone
LP toleranceHigh
Minimum equipmentNaked eye
Optimal equipmentBinoculars
Magnitude-
Size-
ConstellationVulpecula

Observation Notes

Naked Eye

Visible under dark, transparent skies (roughly Bortle 3 or better) as a faint but recognizable hook- or hanger-shaped chain of stars. The shape is subtle and easily missed in light-polluted skies, where only a few brighter members may be seen.

Binoculars

The ideal instrument. The full coathanger shape snaps into view immediately and unmistakably against the rich Milky Way background, making this one of the most rewarding binocular asterisms.

Small Telescope

Requires the lowest possible magnification and a wide-field eyepiece to frame the entire pattern. At higher powers, the asterism breaks apart and loses its visual identity.

Medium Telescope

Not recommended for viewing the asterism as a whole. Better suited for examining individual member stars, including a few attractive optical double stars.

Large Telescope

Unsuitable for viewing the asterism as a pattern. Can be used to study individual stars (colors, separations), but this offers limited aesthetic reward.