M68 is a mag. +7.8 medium sized globular cluster located in eastern Hydra that was discovered by Charles Messier on April 9, 1780. Although not as spectacular as great globulars such as Omega Centauri, 47 Tucanae or M13, it's easily visible with 7x50 or 10x50 binoculars and appears obviously non-stellar. The globular is well seen through medium and large sized amateur scopes.
Hydra is the night sky's largest constellation. However, despite it's immense apparent size it contains only one reasonably bright star, Alphard (α Hya) at mag. +2.0. Despite this, locating M68 is quite easy as it's positioned just south of the relatively bright quadrangle of Corvus (Crv) and 3.5 degress southeast of star β Crv (mag. +2.6).
With a declination of -26.7 degrees, M68 is best seen from the Southern Hemisphere during the months of March, April and May. From northern temperate locations it appears low down and doesn't climb very high above the southern horizon at best.
Through a small 80mm (3.1-inch) telescope, M68 reveals a brighter centre surrounded by a fuzzy halo that gradually fades to the edges. Under nights of good transparency and seeing conditions the outer parts of M68 are resolved in a 200mm (8-inch) scope. The core is not compact and large amateur scopes of the order of 300mm (12-inch) will resolve stars across the full face of the cluster. In total, M68 spans 11 arc minutes of apparent sky, although it appears somewhat smaller through the eyepiece.
M68 is located approximately 33,000 light-years distance. It has a spatial diameter of about 105 light-years and is estimated to contain more than 100,000 stars.
M68 Data Table
|Object Type||Globular cluster|
|RA (J2000)||12h 39m 28s|
|DEC (J2000)||-26d 44m 34s|
|Apparent Size (arc mins)||11 x 11|
|Number of Stars||>100,000|
|Notable Feature||Relatively metal poor cluster|