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Messier 75 - a globular cluster in the constellation Sagittarius

Object description:

Messier 75 is a globular cluster in the constellation Sagittarius, which was discovered in August 1750 by Pierre Méchain. It belongs to concentration class I and is one of the most concentrated globular star cluster. The distance to M 75 is about 67 500 light-years, so the star cluster is on the other side of our galaxy. Due to the long distance, M 75 appears in the sky only at an angle of about 6 arc minutes, the absolute diameter is about 130 light years. It contains about 400.000 stars, the age of the cluster is estimated at about 13 billion years.

The seeing at recording time reached unfortunately only about 3.5'' (FWHM), which is why the result does not seem particularly sharp. A high-resolution image of the cluster center, taken with the Hubble Space Telescope, can be found here.
The image above shows a size comparison to the full moon. Click here or the thumbnail to load a larger version.

Charles Messier observed the star cluster in October 1750, determined its position and added it to his catalogue as object number 75.   He wrote: "... Nebula without star, between Sagittarius & the head of Capricorn; seen by M. Méchain on August 27 & 28, 1780 ..."

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