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The open cluster M39 was officially discovered by Le Gentil in 1750, but Aristotle probably observed it describing it as “cloudy, cometary appearance”. This cluster is rather close to us, less than 1,000 ly and is about 250 million years old. All of its stars are main sequence ones with blue A type dominating. It approaches us at a speed of 28 km/sec.
Additional Information
Object
Name(s): M39, NGC 7092
Type: Open Cluster
RA: 21h 31m 47.8s
Dec: +48º 25’ 59”
Constellation: Cygnus
Size (arcmin): 29×29
Magnitude: +4.6
Distance: 1,000
Image
Date: 2012-10-05
Location: Corbera de Llobregat, Barcelona, Catalonia
Size (arcmin): 37×38
Telescope: Celestron 11” HD f/10
Camera: FLI ML6303 (3072x2048pix)
Guiding: Orion SSAG/Nikkor 500mm f/8
Total exposure: 40 min (L: 10min; RGB: 30min)
Processing: PixInsight