M68

M68 is one of the few globular clusters that I had not imaged before due to its location, south of Corvus, at a declination of nearly -27 degrees. Lying at a distance of about 33,000 light years, this cluster contains about 250 giant stars of absolute magnitude greater than zero, the brightest being of visual magnitude 12.6 and thus M68 appears in our skies at a visual magnitude of just under 8. M68 is spread over a volume of a little more than 100 light years and contains at least 42 variables. A non-member star, FI Hydrae, lies at the outer edge of the cluster and is a Mira-type variable which can become as bright as 9th magnitude, which at that time distorts the appearance of M68. It is approaching us at a velocity of 112 km per second.

Image taken May 25, 2011, with the ST-8 and the C-14 operating at F:11. Exposure is 10 minutes.