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M41, Open Cluster
Messier 41
Exposure Data
  • Image Field of View: 2.31° x 1.54°'
  • Camera Field of View: 3.03° x 2.02°
  • Scope: 70 mm ED doublet refractor
  • Focal Length: 420 mm with 1x field flattener
  • Focal Ratio: f/6
  • Camera: Modified Canon T2i (550D)
  • ISO: 1600
  • Exposure: 4 x 600 seconds (40 minutes total)
  • Filter: Minus Violet
  • SQM: 20.81

Messier 41 is a large, bright, open cluster in Canis Major. It can easily be found four degrees south of Sirius, the brightest star in the night sky.

M41 is large and bright. At magnitude 4.5 it is bright enough to be seen with the unaided eye from a dark-sky observing location. At 39 arcminutes in diameter, it is larger than the full Moon.

The cluster contains 60 stars from magnitude 7 to 11.5, and 150 down to magnitude 13, with ten 7th and 8th magnitude bright stars. The brightest star in the cluster is red giant HD 49091 shining at magnitude 6.9 near the cluster's center. Several other bright stars in the cluster are also red giants.

M41 is located 2,300 light-years away and is 25 light-years in diameter in space. It is estimated to be between 190 and 240 million years old.

M41 was discovered by Giovanni Batista Hodierna before 1654, but it may have been known to Aristotle in 325 B.C.E. It was independently discovered by John Flamsteed in 1702, and also by Guillaume Le Gentil in 1749 and Charles Messier, who cataloged it in 1765.

North is to the top in the above image.

Messier 41
  • Catalogs: M41, NGC 2287
  • Object Type: Open Cluster
  • Magnitude: 4.5v
  • Size: 39'
  • Constellation: Canis Major
  • Image Field Centered At:
    • RA: 06h 46m 09s
    • Dec: -20° 47' 27"

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