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M 7 is commonly known as the Ptolemy
Cluster, named after the Greek-Roman astronomer who first recorded
it in 130 AD. He described it as a nebula. In 1654, the astronomer
Giovanni Battista Hodierma noted that this object was a star cluster,
counting 30 stars in it. Charles Messier added this to his catalogue
in 1764.
With a declination of - 34.8, M
7 is the southern-most of the Messier objects. It lies 980 light
years away and spans 25 light years. It is known to contain 80-100
stars and at a combined magnitude of 3.3, it is easily visible to
the naked eye.
Taken at the Nebraska Star Party
on 8/1/16.
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