Location: Grammatiko, Attiki
Messier
13 (M13), also designated NGC 6205 and sometimes called the Great
Globular Cluster in Hercules or the Hercules Globular Cluster, is a
globular cluster of about 300,000 stars in the constellation of
Hercules.
M13 was discovered by Edmond Halley in 1714, and
catalogued by Charles Messier on June 1, 1764. It is located at right
ascension 16h 41.7m and declination +36° 28'. With an apparent magnitude
of 5.8, it is barely visible with the naked eye on a very clear night.
Its diameter is about 23 arc minutes and it is readily viewable in small
telescopes. Nearby is NGC 6207, a 12th magnitude edge-on galaxy that
lies 28 arc minutes directly north east. A small galaxy, IC 4617, lies
halfway between NGC 6207 and M13, north-northeast of the large globular
cluster's center.
M13 is about 145 light-years in diameter, and
it is composed of several hundred thousand stars, the brightest of
which is the variable star V11 with an apparent magnitude of 11.95. M13
is 25,100 light-years away from Earth.
Δεν υπάρχουν σχόλια:
Δημοσίευση σχολίου