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The globular cluster Messier 55 in the constellation
Sagittarius |
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Short Object description:
M 55 is a beautiful globular star cluster in the
constellation Sagittarius with an apparent diameter of 19 arc minutes in the
sky. The discovery of M 55 goes back to Nicolas Louis de Lacaille on 16 June
1752. Charles Messier added the very southern (-31° declination) cluster
into his catalogue in 1778. The distance to the cluster is 17,000 lightyears
and the absolute diameter is almost 100 lightyears. M 55 belongs to the very
"loose" globular star clusters (concentration class XI) and can be dissolved
very well.
The seeing at imaging
time was about 2.7'' (FWHM). A fascinating deep image of the cluster was taken
with the VISTA telescope at the Paranal Observatory and
can be
found here. |
Click here or the thumbnail image for a comparison with the
size of the Moon. |
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