13 December 2016

Fun with Globulars

Given the time of year, one might wonder why a post about globular cluster observing comes now. There are 2 good reasons. First, it's a good time to plan observing projects that start in a few months. Secondly, I've done a bit of research lately on the Terzan globulars. There is confusion in the astronomical community about the identification of some of these objects. I believe I have this sorted now - results available in the Plan Library. But I digress, slightly...

Globular Cluster M 22 - Photo by Mark Lang
Observing globular clusters can be a very interesting pursuit. If you observe carefully, you'll notice that they all appear just a bit different. Not only in size and star colors, but notably in how many stars you can resolve, and the pattern of concentration. You can also observe globulars in neighboring galaxies.

Deep-Sky Planner provides a number of resources to help. You can search various catalogs in the database, and you can download several plans from the Plan Library that contain specialized lists of globular cluster. Current these include:
  • Astro League Globular Clusters
  • RASC Globular Clusters
  • Palomar Globular Clusters
  • Terzan Globular Clusters.
The AL and RASC lists are designed to educate the observer about observing globulars. They provide a nice sampling of objects and helpful information in their respective publications*. Either is a worthwhile project.

The latter two lists are designed for imagers and observers with large telescopes. The data for these lists are taken from the SIMBAD astronomical database and are supplemented with magnitude and color information gathered by W.E. Harris of McMasters University in Canada.

These are small, faint clusters so you will likely want to download and view DSS images of these objects. Although these clusters have been studied for many years, magnitude and color information is missing for many of the objects.

*AL Globular program material: https://www.astroleague.org/al/obsclubs/globular/globular1.html

*RASC Globular program material: Edgar, James S. Observer's Handbook 2017, Toronto: Royal Astronomical Society of Canada, 2016, p312. Print.

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