An explorer of the heavens without a good star atlas is like a tourist without a road map - both wandering aimlessly without any idea of where they are. Of the many celestial maps, atlases and catalogues available to the stargazer today, we concentrate here on those of particular interest and use to the double star observer.
The author's personal favorite atlas for such work is the "old" Norton's Star Atlas - any one of the 17 editions of this classic before the appearance of the newer 18th edition in 1989, renamed Norton's 2000.0. While the latter now has a symbol for double stars (a line bisecting the star-dot) which the former did not, its editors have sadly dropped the priceless double star designations that were a hallmark of the earlier editions. These consisted of the official symbol or abbreviation for the discoverer of each pair plotted and the catalog number from the corresponding catalogue. Both the old and new editions have the wonderful advantage over more detailed atlases of showing nearly the entire sky visible at a given time of year on a double page, except for the polar regions, which are on separate maps. Both works also contain listings accompanying the maps of some of the more interesting double stars and other deep-sky objects plotted.
In the author's opinion, the finest all-purpose star atlas in existence is Wil Tirion's superb Sky Atlas 2000.0, co-issued by Sky Publishing Corporation and Cambridge University Press. Tirion is generally recognized as the greatest celestial cartographer in the world today. This work is a joy to look at (especially the deluxe color-coded edition) and exciting to use at the telescope, plotting over 81,000 stars to visual magnitude 8.5 along with some 2,700 clusters, nebulae and galaxies over the entire visible heavens on 26 large-scale charts.
A two-volume catalog entitled Sky Catalogue 2000.0, by Alan Hirshfeld and Roger Sinnott, provides data for most of the objects plotted in the atlas. Arranged by object type, the double and multiple star section contains over 8,000 entries. (Also available is the more recent Sky Atlas 2000.0 Companion by Sinnott and Robert Strong, which contains descriptions of every nonstellar object plotted on the atlas.)
Other much more detailed atlases have appeared in recent years, such as Uranometria 2000.0 and The Millennium Star Atlas. Plotting hundreds of thousands (or more!) stars and deep-sky objects, they were published partly in response to the growing use of truly huge, large-aperture Dobsonian-type reflectors by amateur astronomers today. In practice, these massive volumes are often unwieldy and confusing to use at the eyepiece at night. For the purposes of most double star observers, they are definitely overkill.
The ultimate reference in this field is the Washington Double Star Catalog, or WDS. Compiled and maintained by the United States Naval Observatory in Washington, D.C., it is the world's largest collection of data on these objects. Incorporating all previous great discovery catalogues, together with more recent finds and the latest measures of pairs from observers around the world, the latest edition contains entries for over 98,000 double and multiple star systems. It can be accessed on-line at the Observatory's Internet site at http://ad.usno.navy.mil/wds/ (which contains a veritable galaxy of information about these objects) and is also available without charge on a CD-ROM. In addition, a valuable catalog of current visual binary orbits can also be accessed on-line or requested on CD-ROM. Further information is provided on the site itself, where both CDs can be ordered on-line. Those without a computer can contact the Observatory directly by mail at Massachusetts Avenue, NW, Washington, DC 20392, USA.
An extensive listing of official double star designations and catalogues is given in Appendix 2. The symbols and abbreviations shown are based upon the names of the various discoverers, measurers or their institutions, and they span the period from some of the very earliest to the very latest such compilations.
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