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... М38 < М39 > М40 ...

Open star cluster M39

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


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

Visual magnitude: 5,5m - 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.

Nikolay Kurdyapin, astro-map.com  
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