The next step up from a Mag 6 star atlas is Sky Atlas 2000.0 (Sky Publishing, 1999), which is considered by many amateur astronomers to be the gold standard among "serious" star atlases. Sky Atlas 2000.0, or SA2K, covers the entire sky with 26 charts drawn by, you guessed it, Wil Tirion. SA2K charts 81,312 single, multiple, and variable stars of magnitude 8.5 and brighter--which is to say, about nine times as many stars as a Mag 6 atlas--and about 2,700 deep-sky objects, including most of the Herschel 2,500 list. SA2K also includes supplemental detailed charts for the celestial poles, the Coma-Virgo galaxy cluster, and other cluttered areas. It also includes a transparent coordinate grid overlay that provides fields of view for finders, a Telrad, and eyepieces.
SA2K provides much more detail than a Mag 6 atlas. For example, Figure 2 shows the same region around Orion's belt and sword that is shown in Figure 1. Comparing the two figures, it's obvious that the SA2K chart is not only much larger scale, but includes many more objects and more detail about each object.
Many of the objects charted by SA2K are beyond the reach of a binocular or small telescope, even from a dark site. We have heard it said that a skilled observer with a 4" scope at a very dark site can observe all of the objects charted by SA2K. That may be true, but our regular observing sites aren't that dark (and, perhaps, we're not that skilled). We think SA2K is a perfect match for a typical intermediate to advanced amateur astronomer who uses a 6" to 10" telescope from what passes nowadays for a dark site.
If SA2K sounds good to you, the next decision is which version to buy. SA2K is available in six versions:
- Field Version ($30; 13.5" by 18.5"; white stars on black sky; loose sheets)
- Laminated Field Version ($70; 13.5" by 18.5"; white stars on black sky; spiral bound)
- Desk Version ($30; 13.5" by 18.5"; black stars on white sky; loose sheets)
- Laminated Desk Version ($70; 13.5" by 18.5"; black stars on white sky; spiral bound)
- Deluxe Version ($50; 16" by 21"; black stars on white sky, with features highlighted in color; loose sheets)
- Laminated Deluxe Version ($120; 16" by 21"; black stars on white sky, with features highlighted in color; spiral bound)
Both Field Versions use white stars on a black sky, mimicking the appearance of the night sky. The rationale of using these mostly black charts in the field is that they minimize glare and make it easier to remain dark-adapted. In reality, if you use a proper red LED flashlight for viewing charts, your dark adaptation is unaffected, no matter how bright the red light. The downside to the Field Version is that the black background makes it impossible to annotate the charts or to draw in constellation lines, which are not printed on the charts. The two Desk Versions are identical to the Field Versions, except the Desk Versions use black stars on a white background, which we greatly prefer.
The Field and Desk Versions are available either as loose paper charts, at $30 list price, or as laminated, spiral-bound books, at $70 list price. Despite the higher price, many amateur astronomers buy the laminated versions because they are immune to dew, which can quickly wreck unprotected paper charts. We dislike the stiffness of the laminated versions, and prefer to use a standard version and take steps to protect it from dew. The easiest way to do that is simply to cover the charts when they're not actually being used. Covering them with a towel will protect them adequately under all but the worst dewing conditions. Alternatively, Sky & Telescope sells a $28 chart carrier that is specifically designed to carry and protect any version of the SA2K. The chart carrier includes a protective plastic sheet that allows you to view any particular chart while keeping it dry.
Unlike the Field and Desk versions, which use monochrome 13.5" by 18.5" charts, the Deluxe versions use full-color 16" by 21" charts. In addition to making them prettier, we think the use of color adds significantly to the usability of the charts. (The charts are equally readable under white or red light.) The $50 Deluxe Version is spiral-bound into a 12" by 16" book, with each chart folded once. The $120 Laminated Deluxe Version is also spiral-bound, but without folding, yielding an oversize 16" by 21" book that we consider too awkward for use in the field.
On balance, we think the unlaminated Deluxe Version is the best choice for most people. Despite extensive use in the field, our copy remains in good condition, without any dew damage.
The only missing piece in Sky Atlas 2000.0 is an index of the objects it includes. That lack is remedied by the Sky Atlas 2000.0 Companion ($30; Sky Publishing, 2000; ISBN 0933346956) by Robert A. Strong and Roger W. Sinnott. Its nearly 300 pages list and describe each of the 2,700 DSOs charted by SA2K, and cross-reference each object by chart number. We don't use this book, because we generally work with standard catalogs such as the Herschel 400, which list objects by declination and right ascension, making it easy to locate the object in the SA2K charts. But if you want to locate objects in SA2K using only their NGC or other standard designations, the SA2K Companion is essential as an index to the charts.