Messier 13 – this is the name of the brightest globular cluster visible in northern hemisphere in constellation Hercules, that is also called sometimes Hercules Globular Cluster. Apparent brightness is 5.8mag, and under really dark sky it can be spotted with naked eye. The bigger instrument we aim there the more we can observe.
M13 has been discovered by Edmond Halley in 1714. Its apparent diameter is over 20 arc minutes, so quite close to apparent diameter of the Moon.
The cluster is located about 25 000 light years away and contains about 300 000 stars. The brightest star in the cluster is 11.95 mag. The Arecibo message of 1974, containing encoded information about the human race, DNA, atomic numbers, Earth’s position, and other information, was beamed towards M13, as an experiment in contacting potential extraterrestrial civilizations in the cluster. However, the experimenters intentionally sabotaged their goal: the message will reach the cluster’s past position in 25,000 years. By then, the cluster will occupy a different position in space; it will never receive the message 🙂
The globular can be easily recognized in the picture above 🙂 In the upper right corner there is NGC6207 galaxy, and in half way between the cluster and this galaxy, there is another faint galaxy – IC4617. The brighter one is 64 million light years away, and the second galaxy is about half billion light years away. Both are annotated at the picture below, and each cross marks a position of galaxies brighter than 20mag:
However the most remote object I found in the picture is quasar marked in another picture. This remote world is over 11 billion light years away!
Clear skies!
