M37 open cluster, source: NOAO
|Observation data (J2000.0 epoch)|
|Right ascension||5h 52m 19s|
|Declination||+32° 33′ 2″|
|Distance||4.4 kly (1.3 kpc)|
|Apparent magnitude (V)||6.2|
|Apparent dimensions (V)||24′|
|Other designations||w:NGC 2099|
Messier 37 is the brightest of the three open clusters in Auriga. M37 was missed by w:Le Gentil when he rediscovered M36 and M38 in 1749. w:Charles Messier independently rediscovered M37 in September of w:1764 but all three clusters were recorded by Hodierna before 1654. All three clusters were generally unknown until w:1984.
M37 is roughly 300 million years old and contains over 500 stars with roughly 150 stars brighter than magnitude 12.5. M37 also contains at least a dozen w:red giants with the hottest w:main sequence star of w:spectral type B9V. Its distance is between 3,600 and 4,700 w:light years and the apparent diameter of 24' corresponds to a w:linear extension of about 20 to 25 light years. It is classified as Trumpler type I,1,r or I,2,r.