If Sky Atlas 2000.0 is the gold standard in serious star charts, then Uranometria 2000.0 (U2K) must be the platinum standard. As useful as SA2K is, it doesn't go deep enough for many serious astronomers, particularly those who observe with larger instruments from very dark sites. If your scope is at least 8" to 10" and you observe from a reasonably dark site, you'll see many prominent objects that don't appear in SA2K. Welcome to the world of serious DSO observing.
Dedicated DSO observers consider Uranometria 2000.0 their bible. Uranometria 2000.0 charts 280,000+ stars down to magnitude 9.75 and 30,000+ deep-sky objects. That's more than three times as many stars as SA2K and more than ten times as many DSOs. In a region where SA2K charts two or three galaxies, for example, U2K may chart 20 or 30. U2K also includes 26 even more detailed charts of cluttered regions, with a limiting stellar magnitude of about 11.0.
With the exception of the Millennium Star Atlas, now out of print and selling for $500 used, U2K is by far the deepest mainstream printed star atlas available. And, although MSA goes deeper than U2K for stars, U2K goes much deeper than MSA for DSOs. The only close competition for U2K is the Herald-Bobroff AstroAtlas. Some observers like the HBA, but we consider it too cluttered for use in the field.
Figure 3 shows the same region around Orion's belt and sword in U2K shown in Figure 2 for SA2K. At first glance, the level of detail may seem similar, but closer examination shows that U2K provides significantly more detail than SA2K. Look, for example, at the region between Alnitak and Alnilam, where many more stars are visible on the U2K chart. Also examine the region of the Great Orion Nebula, where U2K again provides immensely more detail.
Uranometria 2000.0, by Wil Tirion, Barry Rappaport, and Will Remaklus, is packaged as a three-volume set of hardback books. Uranometria 2000.0 Deep Sky Atlas Volume 1 ($50; Willmann-Bell, 2001; ISBN 0943396719) covers the northern hemisphere from declination +90° to -6°. Uranometria 2000.0 Deep Sky Atlas Volume 2 ($50; Willmann-Bell, 2001; ISBN 0943396727) covers the southern hemisphere from declination -90° to +6°. Both of these volumes are necessary for complete coverage of the night sky. Uranometria 2000.0 Deep Sky Field Guide Volume 3 ($60; Willmann-Bell, 2001; ISBN 0943396735), by Murray Cragin and Emil Bonanno, lists and indexes every DSO charted by the two atlas volumes. Each of the 220 double-page charts in the atlases has a corresponding table in the Field Guide that lists co-ordinates, dimensions, classification, and notes for every object plotted on that chart. The Field Guide also includes a full index that lists every object and is cross-referenced to the appropriate chart number. All volumes are printed on high-quality paper. Although they are not dew-resistant, taking minimal precautions such as closing them when not in use will keep U2K in good shape through years of field use.
The real decision in choosing printed charts is where to stop. Even the deepest printed charts cannot plot every object visible in large scopes from dark sites, so at some point most dedicated DSO observers find themselves abandoning printed charts for planetarium software, which has no such limits.
For most observers, we think Sky Atlas 2000.0 is the ideal compromise in terms of depth, cost, and usability. We observe primarily with a 10" scope from reasonably dark sites, and find that SA2K is a good fit in terms of objects plotted versus objects visible with our equipment. When we observe from a darker site or with a larger instrument, we use our notebook computer running Xephem or Cartes du Ciel to chart the truly faint fuzzies or beg a few minutes with an observing buddy's copy of Uranometria 2000.0.
If you observe mostly faint DSOs from a dark location with an 8" or larger scope, and particularly if you don't have a notebook computer you're willing to risk in the field, don't bother buying SA2K. You'll be much happier with Uranometria 2000.0.
Robert Bruce Thompson and Barbara Fritchman Thompson are experienced amateur astronomers, co-founders of the Winston-Salem Astronomical League astronomy club, and the co-authors of several O'Reilly books, including Astronomy Hacks, Building the Perfect PC, PC Hardware Buyer's Guide, and PC Hardware in a Nutshell.
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