M39 — Open Cluster in Cygnus

A large open cluster in Cygnus, its young blue stars scattered across an area as wide as the full Moon, visible with binoculars.

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Object type
Open cluster
Constellation
Cygnus
Designation
M39 (NGC 7092)
Distance
≈ 1,000 light-years
Apparent magnitude
4.6
Apparent size
31 arcmin
Best season
Summer / Autumn (best visibility in Aug-Sep)

The open cluster M39 (NGC 7092) is a loose group of young stars near the tail of Cygnus, not far from Deneb. Its low density and large apparent size — almost that of the full Moon — make it better suited to binoculars or small wide-field instruments than to classic telescopes.

In this image, the cluster’s bluish stars stand out clearly, scattered across a wide field, against a dense stellar background typical of this region of the Milky Way.

Session shot on the night of 2026-07-25 with the Seestar S30 Pro mounted in equatorial mode on the EQ3: 196 sub-exposures of 30 seconds each, for about 1h38 of total integration, stacked and processed in Siril.

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