Notes on the Globular Cluster Program
A globular cluster is a collection of thousands upon thousands of stars that are bound together by gravity and form a spherical mass in the night sky. You can learn more about “globs” here, here, and here. The Astronomical League sponsors an observing program that requires the observer to view or photograph 50 globular clusters from a list of 190. The program’s photographic option to be done from a remote site. The program also requires the observer to classify their selected globulars by means of a system developed by astronomers Harlow Shapley and Helen Sawyer Hogg. You can learn more about this classification system here.
I have elected to pursue this program using the remote photographic option. In my Arp Peculiar Galaxy program — also featured on this website — I used the remote photo service sierrastars.com and I will use it again for the globular program. For the Arps, all of my photos were taken at the Warrumbungle Observatory in New South Wales, Australia. This time, I will use the Warrumbungle scope as well as the Gemini scope which is located in Sonoita, Arizona in the United States.
I have experimented a bit with length of exposure. However, I have tentatively concluded that a brief 60 to 90 second exposure is sufficient to capture the detail necessary for the program. I have gently tweaked the .fit files provided by sierra stars using Pixinsight. As in the case of the Arps, I also include a link to SIMBAD (the Set of Identifications, Measurements, and Bibliography for Astronomical Data) operated by the Centre de Données astronomiques de Strasbourg (CDS) that provides additional information about the object in question. For this program I also add a link to the relevant Wikipedia page (if available).