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Hemisphere:  Southern  ·  Contains:  M 7  ·  NGC 6416  ·  NGC 6441  ·  NGC 6444  ·  NGC 6475
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Messier 7, 


            Roberto Colombari
Messier 7
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Messier 7

Technical card job: 1144227

RA center: 17h 52' 42"

DEC center: -34° 44' 38"

Pixel scale: 6.160 arcsec/pixel

Orientation: -90.434 degrees

Field radius: 3.386 degrees

Resolution: 620x454


Messier 7
Image recorded with my Nikon 180mm and SBIG8300 from Belo Horizonte.

R: 19x150s F2.8
G: 16x210s F2.8
B: 15x500s between F5.6 and F8

Copyright: R. Colombari

Messier 7 or M7, also designated NGC 6475 and sometimes known as the Ptolemy Cluster,[4] is an open cluster of stars in the constellation of Scorpius. The cluster is easily detectable with the naked eye, close to the "stinger" of Scorpius (also called Scorpio[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 a nebula 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".[4]

Broader view of M7, the cluster is at the center of this photograph.

The star cluster Messier 7
Telescopic observations of the cluster reveal about 80 stars within a field of view of 1.3° across. At the cluster's estimated distance of 980 light years this corresponds to an actual diameter of 25 light years. The tidal radius of the cluster is 40.1 ly (12.3 pc) and it has a combined mass of about 735 times the mass of the Sun.[3] The age of the cluster is around 200[2] million years while the brightest member star is of magnitude 5.6. In terms of composition, the cluster contains a similar abundance of elements other than hydrogen and helium as the Sun.[2]

Source: Wikipedia



Roberto Colombari
License: None (All rights reserved)

Sky plot

Sky plot


Messier 7, 


            Roberto Colombari

In these public groups

Imagers of Italy