... М38 < М39 > М40 ...

Open star cluster M39

Open star cluster M39 is in the constellation Cygnus (Cyg).

Equatorial coordinates (epoch J2000):
Ra (α):21^h31.8^m, Dec (δ):+48° 26'

Visual magnitude: 5,5^m - this object can be seen with the naked eye on a black sky, in the absence of illumination from street lighting.
Distance from the star clusters M39 to the Sun is 1010 light years
Angular size: 30'
Class: d
External dimensions the star clusters M39 are about 9 light years.
Number of stars: 60
Age of the object M39 is 240—480x10⁶ years

Discoverer: Charles Messier, 1764 year.

The designation M39 in other catalogs: NGC 7092

Optimum magnification for a telescope with observations of M39, depending on the aperture of the telescope (D), is about 10x-20x. Higher magnifications of course add details, but lead to a strong drop in the brightness of the image, making it difficult to observe.

The best month for observing M39 is August. At this time, the object is at midnight near its highest point in the sky, that is, it is less affected by light from the lanterns and atmospheric distortions.

Мessier 38

Мessier 40

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