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SKY ATLAS 2000.0 Deluxe Version, 2nd Edition
Ever since 1981, when it supplanted Becvar's ATLAS OF THE HEAVENS 1950, SKY ATLAS 2000.0 has been truly one of the "standard" wide-field atlases for the amateur astronomer interested in locating and observing deep-sky objects. It was often the atlas most relied upon by amateurs working on the Messier or Herschel 400 observing projects. However, even with its expanded list of objects, better plotting, and fainter limiting magnitude, there was still some room for improvement in the work. I am pleased to say that most of those improvements have indeed been made with the 2nd edition of SKY ATLAS 2000.0. Although not pushing into the extreme reaches of the deep-sky covered by the narrower-field atlases like Uranometria or the Millennium Star Atlas, this new version is a well-crafted intermediate level work which has plenty to offer those amateurs who have outgrown the more simple beginners atlases. The old features have been beefed up and a few new ones have been added, which once again should set this new edition among the better sources of charting information for the amateur.
The new Deluxe version is an attractive 31 page bound publication, with a flexible Lexan cover over front and back. It is slightly larger in scale than the old first edition, with pages being 21.5" x 16.5" (the 1st Edition was 20.5" x 15.5"). Like the original edition, this one has spiral-bound charts which fold out from about half size to their full length, so laminating is probably somewhat impractical unless the pages were unfolded and rebound (there is a version available where this is done). The paper is a rather smooth grade of very white material which may be a little more difficult for those attempting to turn the pages with gloves on. The chart scale is about 8.2 millimeters per degree on the sky, compared to the 7.8mm/deg. of the 1st edition (and the field and desk versions of the 2nd edition), although the areas of sky covered by each chart remain about the same in both editions. In addition to the 26 main skycharts covering the entire celestial sphere, two appendix charts ("A" and "B"), have been added for expanded-scale (2.5x) coverage of seven specialized regions; the North and South Celestial Poles, Barnard's Star and Promimxa Centauri, the Pleiades, the central part of the Virgo Galaxy Cluster, and the central portion of Orion. The magnitude limit for the Second Edition's main 26 charts is now 8.5, meaning that, counting multiple and variable stars, this atlas has 81,312 stars (compared with only 43,000 in the first edition). The appendix larger-scale charts have a magnitude limit of 10.5 and a scale which makes navigating in the "Realm of the Galaxies" a good deal easier. However, the larger-scale charts of the polar regions showing the movement of the celestial poles are really somewhat redundant and add little to the atlas. It probably would have been better to instead have larger-scale charts covering things like a few of the more crowded areas of the Milky Way, or the Fornax Galaxy Cluster. The wider-scale chart key (showing the areas of chart coverage and all stars to 5th magnitude), as well as the new more comprehensive index (containing constellations, the named stars, and even the Messier Objects), make locating the chart of interest quite easy.
One major improvement is in the way the stars are depicted. The new version has taken advantage of new more accurate databases and computer graphics to allow a continuous range of star-dot sizes to depict each star brightness level, rather than the old 1-magnitude star binning which irritated some observers. This makes a very noticable difference over the old version, as the charts now seem cleaner, with a less "busy" and much more natural or realistic starfield. This makes star pattern recognition easier than with the first edition. Indeed, directly comparing the new edition with the old makes the first edition often look a little crude! The printing and object lables are from 10 to 20 percent larger, and are easier to read in dim light (the Deluxe Edition uses black stars on a white background, which is often best for field use). The Milky-Way is now plotted with four brighness-level "isophotes" of differing shades of blue, making the depiction correspond closer to reality. Dark Nebulae are plotted as white with a dotted outline, and many are labeled with their Barnard designations or proper names. Objects with sizes greater than 10 arc minutes are shown to scale, with nebulae outlined in shape and all galaxies shown with the correct aspect ratio and position angle. The standard DSO symbols used in the first edition are still used in the second (circles for clusters and planetaries, boxes or outlines for nebulae, and ovals for galaxies). For the really small objects, the slightly smaller symbol size, while more realistic, does tend to make some of the galaxies a bit less noticable. Nebulae outlines are filled in green, star clusters in yellow, and galaxies in red. One nice feature is the on-chart printing of the names of 192 "named" stars, as opposed to the mere 28 named on the old edition. The common names of a number of deep-sky objects (ie: Barnard's Loop, The California Nebula, Hubble's Variable Nebula, The Great Orion Nebula, ect.), are also printed on the new charts. The catalogs for the various DSO's have also been expanded to include 23 different label designations.
The charts plot about 2700 of the more prominent deep-sky objects (open and globular clusters, diffuse nebulae (light and dark), planetary nebulae, and galaxies), as compared with only 2500 in the first edition. The authors thought a modest increase in the number of objects would be best. I tend to agree with this judgement, considering many amateurs might be using the new version for their initial forays into the realm of the Deep-sky. Too many objects would tend to make the atlas too cluttered for easy use, increasing the confusion and needlessly duplicating the efforts of the deeper atlases like Uranometria. The list of objects plotted has been reviewed and revised using more current data, so a few of the faintest objects which were on the old edition have been eliminated from the new one. The limits on object coverage are now more codified, as the old version had a few inconsistencies in which objects were plotted and which were not. The 2nd Edition plots open clusters with total integrated magnitudes of 8.5 or brighter, globulars to 11.0, galaxies with a blue-light magnitude to 13.0, and Planetary Nebulae to a blue light magnitude of 14.0. The variable stars which are plotted have also been limited to those with a maximum magnitude of 8.5 and which have a range of 0.5 magnitudes or larger (past historic Novae and Supernovae which have risen to 6th magnitude or brighter are also shown). A few people may miss things like constellation lines on the main charts, but these are present on the Index charts, and I feel that they would only add to the clutter on the main ones.
Those engaged in the Messier and Herschel 400 observing programs should find the Second Edition of the Deluxe version a welcome addition to their observing arsenal. The atlas comes with a new slightly thicker clear plastic celestial grid overlay marked to 10 arc minutes in declination and one minute of Right Ascension at the Celestial equator (it even includes the circles of the Telrad reticle!). This will allow the user to determine the the location of objects by their celestial coordinates alone. I particularly enjoyed seeing things plotted like the Medusa Nebula and "the Fingers" nebula (Sh-2-157) on the new version, as both were missing from the first edition. Even a number of the objects on the Herschel II list made it into the Atlas, although for that more challenging observing project, it would still be better to have something like Uranometria on hand. However, Sky Atlas 2000.0 with its computerized plotting does goof up on occasion. The large 9th magnitude planetary NGC 1360 in Fornax is not plotted, as apparently the lable field for the variable RZ Fornacis prevented the planetary from being printed.
So, how does this atlas work in the field under a dim red light? Pretty well, actually. The continuous star dot sizes made for a much better comparison to the patterns I saw visually on the night sky, and the Telrad reticle on the plastic overlay was a really nice addition. The larger labels are easier to read than in the first edition, and the Milky-Way isophotes still showed their intensity variations and boundaries. The borders of the constellations were a bit harder to see (fine dotted lines instead of the more coarse dashed ones of the old edition), but otherwise, most of the features plotted were quite viewable under my red LED flashlight. In particular, the dark nebulae (plotted in white) stood out like sore thumbs! The bright nebulae depictions also stood out well under the red light, and even the tiny ovals of the galaxies were clearly filled with darker red color even under the LED light. The smooth paper of the pages was almost glossy in feel, making it necessary to take my gloves off to open the charts sometimes, but I am uncertain as to how dew will affect this new surface. I usually keep my books and atlases in the open back of my minivan when observing, so dew is never really much of a problem. As with most atlases used at night, I do recommend a large-scale magnifier, possibly with internal illumination, to help prevent eyestrain. A new version of the Sky Atlas 2000 Field Guide is also now available from Sky Publishing. It contains much of the numerical data on all the non-stellar objects plotted on the atlas.
On the whole, I find the new Second Edition of SKY ATLAS 2000.0 Deluxe to be a work of high quality and usability, which will easily serve the needs of many amateur astronomers for years to come.