Russell Croman Astrophotography  



The Great Hercules Cluster

About This Photograph

Globular clusters are vast swarms of ancient stars that inhabit the halo of our galaxy, outside of the main disk where most of the stars (and the Earth) reside. They can contain anywhere from ten thousand to a million stars. These stars orbit the collective center of mass of the cluster in a veritable bee hive of motion, and the cluster itself orbits the Milky Way as a distinct object, occasionally plunging right through the main disk and out the other side. Although the cluster appears extremely dense, the distance between individual stars is actually quite large. As a result, stars within them rarely collide, and in the main globular clusters survive relatively unscathed by their passage through the galaxy's disk.

Many other galaxies are known to host globular clusters. The Sombrero Galaxy (M104), for instance, has a rich collection.


Technical Details

Optics:20" f/8 RCOS Ritchey-Chrétien Cassegrain w/ RCOS Field Corrector.
Mount:Software Bisque Paramount ME.
Camera:SBIG STL-11000XM.
Filters:SBIG Standard LRGB.
Dates/Times:10 May to 4 June 2005.
Location:Dimension Point Observatory, Mayhill, New Mexico.
Exposure Details:LRGB = 120:60:30:60 minutes, two-frame mosaic.
Acquisition:MaxIm DL/CCD 4, TheSky6, CCDAutoPilot2.
Processing:MaxIm DL/CCD 4, Photoshop CS, GradientXTerminator.