Terzan Globular Cluster Project

Discovered during infered light survey's in the late 1960's by Argop Terzan. The Terzan's are problematic due to there location...that being near the center of the Milky Way. Also they sit behind a good amount of glactic dust. Thus making them somewhat faint...even fainter than some Palomars. Since most of the data on the Terzans is sketchy at best I hope to set the record straight on imaging, aperture, and location of these objects. In addition, initially there were 12 Terzan globular clusters.  But after careful examination of these objects Argop, found that Terzan 11 was a duplication of Terzan 5. This brought the Terzan’s down to 11. Thus making Terzan 12 Terzan 11. This sometimes creates some confusion/discrepancy with some of the older sky maps and guides.  So it is important to make sure that when observing Terzan 11 the information is correct.

Since there is little observational data on the Terzan's, I found it important to clear up and at the same time add to the current body of knowledge. The first big misconception regarding the Terzans; that being the need for extreme aperture to view them. All of these observations have been done with apertures of between 14 and 16 inches...no larger! The second is there location; being located in a region of the sky (Sagittarius and Scorpius) makes it very difficult for northern observers to view. For most, these globular's are located near or close to the horizon. Thus making them difficult to see and putting them off the radar for most observers.

From my own experience, and from having to have observed all the Terzans, is that they are only somewhat more difficult to observe than the Palomars. The few Terzans that run into the 15 and 16th magnitude may well need larger aperture for better viewing. But from my experience, dark skies and a few minutes of imaging can coax them out (see Terzan images). So far I have not needed the larger glass for viewing. Initially, I was somewhat apprehensive about my being able to observe these globular clusters at all. Again this was based on the limited information that I was able to gather. Observing the Terzan's has been much easier than first thought. These globular clusters are well within the range of large amateur scopes in the 14 to 22 inch range. For southern observers who have access to Sagittarius and Scorpius being higher in the sky....there may be the potential to see some of these fabulous objects with smaller aperture scopes. This would make for some interesting research. Hopefully, someone out there can get back to me with information. By the way, special thanks to Matt Pettini of RGO for his techical input and support with this project.

My current ranking (ROD) Recascino's Order of Observational Difficulty of the Terzan Globular Clusters are as follows; Order to be posted soon.

Link to Terzan Images

Terzan Coordinate List courtesy of Ntko Bajic