Ptolemy Cluster

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Messier 7 or M7, also designated NGC 6475 and sometimes known as the Ptolemy Cluster, is an open cluster of stars in theconstellation of Scorpius. The cluster is easily detectable with the naked eye, close to the “stinger” of Scorpius (also called Scorpion[5]). With a declination of -34.8°, it is the southernmost Messier object.

M7 has been known since antiquity; it was first recorded by the 1st-century Greek-Roman astronomer Ptolemy, who described it as anebula in 130 AD.[6] Italian astronomer Giovanni Batista Hodierna observed it before 1654 and counted 30 stars in it. In 1764, French astronomer Charles Messier catalogued the cluster as the seventh member in his list of comet-like objects. English astronomer John Herschel described it as “coarsely scattered clusters of stars”.

Imaging telescopes or lenses: North Group 80mmF6 Triplet
Imaging cameras: Nikon D7000
Mounts: Losmandy G11 Astrometric Skywalker
Guiding telescopes or lenses: Orion 80mm f/5
Guiding cameras: Orion Starshoot Auto-Guider
Software: Diffraction Limited MaximDL 5 Pro
Resolution: 4948×3280
Dates: Nov. 6, 2013
Locations: Leyburn Dusty Downs Observatory – Dark Sky
Frames: 8×120″
Integration: 0.3 hours
Avg. Moon age: 2.72 days
Avg. Moon phase: 8.15%

Author: Greg Bock

AstroPhotography of the day of SPONLI, 16.10.2014