Open Cluster Club Introduction - Printable

Open Cluster Club Chair:

Benjamin Jones
9322 Tyler Oaks
Helotes, Texas 78023
(210) 378-0835




Open clusters are of tremendous importance to the science of astronomy, if not to astrophysics and cosmology generally. Star clusters serve as the "laboratories" of astronomy, with stars now all at nearly the same distance and all created at essentially the same time. Each cluster thus is a running experiment, where we can observe the effects of composition, age, and environment. We are hobbled by seeing only a snapshot in time of each cluster, but taken collectively we can understand their evolution, and that of their included stars. These clusters are also important tracers of the Milky Way and other parent galaxies. They help us to understand their current structure and derive theories of the creation and evolution of galaxies. Just as importantly, starting from just the Hyades and the Pleiades, and then going to more distance clusters, open clusters serve to define the distance scale of the Milky Way, and from there all other galaxies and the entire universe.

However, there is far more to the study of star clusters than that. Anyone who has looked at a cluster through a telescope or binoculars has realized that these are objects of immense beauty and symmetry.

Whether a cluster like the Pleiades seen with delicate beauty with the unaided eye or in a small telescope or binoculars, or a cluster like NGC 7789 whose thousands of stars are seen with overpowering wonder in a large telescope, open clusters can only bring awe and amazement to the viewer.

These sights are available to all. Whether a large or small telescope is used, whether one observes with only binoculars or the unaided eye, or whether one observes from a dark sky location or a light-polluted city, these clusters are there waiting on any clear night for us to take a look.

Performing this program and receiving the certificate and award pin, signifies that you too, have undertaken the task of studying these wonderful and diverse star systems and hopefully, have a new understanding and appreciation for these deep sky objects.

Rules and Regulations

The Open Cluster Observing Program is open to any Astronomical League member in good standing, either through an affiliated club or through a Member-at-Large membership. The nature of this program is not just observation of the selected open clusters, but the ability to classify them based on the Trumpler classification system. Therefore, GO-TO and other computer controlled telescopes are permitted along with manual (star hopping, finderscopes, etc.) observing techniques. In order to complete the requirements for the club, the observer is required to observe all 125 (one-hundred and twenty-five) of the selected objects.

Other than observation, the observer will be required to classify all of the open clusters observed in this program under the Trumpler classification system. Examples of some of the official Trumpler classifications are given in the observing manual. By classifying all of the open clusters, the observer will be developing a better understanding of their differences and appearances.

The observer is also required to make a sketch of any 25 (twenty-five) clusters they observe. The sketch does not have to be a work of art, but it does need to accurately depict the cluster. Since open clusters are made of stars, a drawing of small dots in a pattern of the cluster is all that is needed. Only 25 objects need to be sketched.

Because the goal of this program is to have the observer see the differences in the clusters, it is highly recommended that the same telescope and similar power be used for all of the clusters. By doing this, it will ensure that the differences that are seen are cluster differences and not power differences.

For each object, the observer is required to record the location, date & time, seeing, transparency, aperture, power, a brief description of the observed object, the Trumpler classification, and a sketch for any 25 clusters from the list of 125. This format follows that of most Astronomical League observing programs. If the format that you use is more detailed, just make sure that the basic requirements, described above, are recorded.

Once you have met the above requirements, send in your observing logs, along with your name (as you wish it to appear on your certificate), address, Astronomical League affiliation (club name or member-at-large), email address and phone number to the administrator of this club, shown at the top of this web page. It is also permissible to have your clubs' Astronomical League Awards representative send in your logs, along with all the personal information ask for above, to the administrator as well. Remember to make copies of your observations to send it. Keep the originals for your own records.