Messier 37 (also known as NGC 2099 ) is the most beautiful of the three open clusters in the winter constellation Auriga, which are included in the Messier catalog. His brightness is like 5.6, its angular extension 24 '.
He stands 4 ° south of the star θ Aurigae and can be detected at freiäugig ideal dark sky. In binoculars, it shows an oval nebula from 8-12 stars 9.Größe, in the classic eight- inch (20cm reflecting telescope ) already about 150 stars. They are focused clearly on the center, but have a bar-shaped star gap in the northeast on.
Of the approximately 2000 stars are brighter than 13 mag 200, including about 15 red giants, 20 variables and 30 double stars. In the cluster center, the striking F8 star HD 39183 is 9.2 mag. Because of its large star number M37 served many astronomers as an object for study of stellar evolution, such as by color-magnitude diagram.