What happened to Terzan 7?

Willmann-Bell has been around longer than I've been stargazing. Perhaps best known for Uranometria 2000.0, which I've become convinced is a must-have, they offer other publications of interest. I recently wrote of their excellent The Arp Atlas of Peculiar Galaxies, both a history lesson and reference. I can't say it enough: we can't control the weather, so what better activity when it doesn't cooperate than to study?

Incidentally, I see no reason not to order their books directly from them. You can't order from Amazon or Barnes and Noble at discount. Willmann-Bell processes an order very quickly and their free shipping option, within the U.S., at least, is first class – not the slower and cheaper media shipping.

I had passed up Star Clusters, by Brent A.Archinal and Steven J. Hynes, telling myself that I really wasn't particularly interested in clusters: I'm more of a galaxy and nebula man. I forgot globular clusters, which are of interest, and which are covered in this book.

Indeed, this book is a comprehensive resource of both star and globular star clusters, both galactic, and extra-galactic. It covers both the astrophysics in detail. Perhaps its greatest service is in providing a carefully researched and corrected catalog of clusters. This may seem redundant, but there are a number of overlapping catalogs with sometimes incorrect data. This pulls them together.

As I said, I fail to get too excited over "regular" star clusters, which seem like little more than asterisms in most cases, and which can be so obscure as to defy interest. Globulars provide a more consistent challenge, and there are fewer of them. There are some intra-galactic globulars that present interesting challenges. There is a "short dozen" from the Terzan catalog that don't overlap with the NGC or IC catalogs. By "short dozen," I mean there are actually 11, because Terzan 5 and Terzan 11 are the same object. All eleven are in Sagittarius and Scorpius, and small and dim. They aren't plotted on the SkyAtlas 2000.0, but they are on Uranometria.

Interestingly, Terzan 7, which is probably the most visible, is missing from the Star Clusters discussion and index, although there is an image.

Star Clusters has an interesting discussion of the various catalogs. I was surprised to see that one important source was the Deep Sky Field Guide, First Edition. This was published after the first edition of Uranometria, listing information on all deep sky objects plotted. I remember when it came out: it was a unique resource. In fact, you want to be careful about getting used copies of Uranometria, avoiding the first edition. The (corrected) Field Guide is now Volume 3 of Uranometria, and I think it is an important and convenient enough reference to carry around in the field with me.

Why all the fuss over Terzan 7? Ultimately, it was sparked by Wildcard Innovations' picture of their Argo Navis Digital Telescope Computer, which uses it on their promotional picture display, probably to underscore the fact that it has a very large catalog of objects. More on Argo Navis later: I should have mine next week.