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Great Southern Globulars Collage
Great Southern Globulars Collage.jpg
This is a collage of the Top 9 globular clusters in the southern hemisphere skies.
Of the group, only Omega Centauri and Messier 22 can be observed from northern latitudes, and then not well as they lie low in the south for many observers. As such, northerners consider the Great Hercules Cluster, Messier 13, a superb target. But it pales in spectacle compared to almost all the globulars here. The best deep-sky objects are in the austral skies!
All the images were taken with the same telescope at the same focal length and with a similar set of exposures, to allow a ready comparison between the clusters' sizes and appearances.
Some, like 47 Tucanae and NGC 2808, are richer than the others with dense bright cores. In the classification scheme devised by Harlow Shapley and refined by Helen Sawyer Hogg and Henrietta Swope, they are Concentration Class III and I respectively, on the scale that runs from Roman Numeral I (most densely packed) to XII (loosely concentrated).
Examples of the other end of the scale shown here are NGC 3201 and NGC 4372, at Class X and XII, respectively. They appear visibly looser to the eye and camera, with fewer stars distributed more evenly across their disks.
The central object in this collage, fittingly so, is in a class by itself. Omega Centauri, aka NGC 5139, is so large and rich it is classified as a dwarf galaxy, or at least the core of an ex-dwarf galaxy. It is the largest globular in angular size in our sky (it is large even in binoculars), but it is also intrinsically the largest Milky Way globular known, at 150 light years across. Within its volume is an estimated 10 million stars — it would never be night on any planet in Omega Cen!
47 Tucanae is second only to Omega for visual spectacle in the eyepiece of any telescope, though many observers consider it the better of the two globulars, with its dense core that can exhibit some color.
NGC 6723, while technically in Sagittarius, lies next to the complex of bright refl
Of the group, only Omega Centauri and Messier 22 can be observed from northern latitudes, and then not well as they lie low in the south for many observers. As such, northerners consider the Great Hercules Cluster, Messier 13, a superb target. But it pales in spectacle compared to almost all the globulars here. The best deep-sky objects are in the austral skies!
All the images were taken with the same telescope at the same focal length and with a similar set of exposures, to allow a ready comparison between the clusters' sizes and appearances.
Some, like 47 Tucanae and NGC 2808, are richer than the others with dense bright cores. In the classification scheme devised by Harlow Shapley and refined by Helen Sawyer Hogg and Henrietta Swope, they are Concentration Class III and I respectively, on the scale that runs from Roman Numeral I (most densely packed) to XII (loosely concentrated).
Examples of the other end of the scale shown here are NGC 3201 and NGC 4372, at Class X and XII, respectively. They appear visibly looser to the eye and camera, with fewer stars distributed more evenly across their disks.
The central object in this collage, fittingly so, is in a class by itself. Omega Centauri, aka NGC 5139, is so large and rich it is classified as a dwarf galaxy, or at least the core of an ex-dwarf galaxy. It is the largest globular in angular size in our sky (it is large even in binoculars), but it is also intrinsically the largest Milky Way globular known, at 150 light years across. Within its volume is an estimated 10 million stars — it would never be night on any planet in Omega Cen!
47 Tucanae is second only to Omega for visual spectacle in the eyepiece of any telescope, though many observers consider it the better of the two globulars, with its dense core that can exhibit some color.
NGC 6723, while technically in Sagittarius, lies next to the complex of bright refl
