For example, Figure 1 shows the cluttered belt and sword region of the constellation Orion as shown on the Mag 6 Orion DeepMap 600 chart. Only the brightest stars and DSOs appear on this chart, and the small scale means that it can be difficult to determine which label refers to which object. This is not a slam on the Orion DeepMap 600; in fact, it's one of the better Mag 6 charts.
When you want just an overview of bright stars and objects rather than a detailed (and cluttered) view, a Mag 6 atlas is just what you need. We always have a Mag 6 atlas handy for that reason.
Here are the Mag 6 star atlases we use and recommend:
- Orion DeepMap 600 ($15; Orion Telescope and Binocular Center) uses maps drawn by the incomparable uranographer Wil Tirion and is unique among star atlases. Rather than loose individual maps or bound map pages, DeepMap 600 is a single large page that folds up like a standard roadmap. It is printed on water-resistant, tear-resistant plastic stock, and is quite durable. The front of DM600 covers the night sky from declination -60° to +70°, with the north circumpolar region appearing as a separate map on the rear side. (The south circumpolar region is not covered.) DM600 charts more than 500 of the brightest DSOs, including the Messier Objects, and about 100 of the brightest and most interesting double and variable stars. Its portability and durability make it an ideal part of a portable kit. With just a binocular and DM600, you're ready for an impromptu observing session any time.
- Bright Star Atlas ($10; Willmann-Bell, 2001; ISBN 0943396271) features objects selected by noted astronomer Brian Skiff and maps by the ubiquitous Mr. Tirion. BSA divides the night sky into ten charts, showing stars down to magnitude 6.5, open and globular star clusters to magnitude 7.0, galaxies to magnitude 10.0, and double stars and nebulae visible in small scopes. Facing each full-page map is a full-page table of the objects plotted on that map and their characteristics. At only 32 pages, BSA contains little of the supplementary information included in book-size atlases. It limits itself to providing first-rate Mag 6 maps and tabular information to support the maps. As such, BSA is an ideal companion for field observing sessions with the naked eye, binocular, or a small telescope.
- Norton's Star Atlas ($30; Pi Press, 2003; ISBN 0131451642), edited by renowned astronomer Ian Ridpath, is probably the most popular of the book-style Mag 6 atlases. It maps the entire night sky with seven double-page maps that cover declination -60° to +60°, with the north and south circumpolar regions from declination ±60° to ±90°, each allocated a double-page map. The scope of objects covered is similar to BSA, including the tabular lists of objects. Unlike BSA, which provides only star maps and lists of objects, Norton's Star Atlas devotes a significant percentage of its 200+ pages to general information of interest to amateur observers. That makes it clumsier to use in the field, but an excellent desk reference when a Mag 6 atlas suffices.