Open Cluster in Cygnus

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Messier 39 is a large, coarse open cluster of about 30 bright stars in a triangular shape, about 950 light years away.  It occupies an area of sky about the size of the full moon, and it can be seen with the naked eye as a dim hazy patch about 10 degrees northeast of Deneb, the brightest star in Cygnus.  Through binoculars, a dozen or so stars can be seen, and with a telescope at low power, its blue-white stars shine brightly against the Milky Way background.

Magnitude 4.6
Apparent Size 32'
Distance (light yrs) 950
Right Ascension 21:32.2
Declination +48 26
Field of View 124' x 93'

Image details:  Exposure times of 15 minutes each of luminance, red, green, and blue, taken with an SBIG ST-8300M imager and a 500-mm Tokina lens at f/8.

June 2017