Review by Joe Benderavage, April 2006.
The Sky Atlas 2000.0 (second edition) by
Wil Tirion and Roger W. Sinnott, 1998,
Sky Publishing, Cambridge University
Press, Cambridge, Mass., is a set of 26
star charts in large fold-out format (22”
by 16”). It includes both celestial
hemispheres as well as detailed charts of
seven areas: both celestial poles; Virgo
galaxy cluster; Central Orion; Barnard’s
Star; Pleiades; and Proxima Centauri.
This is the second edition of a similar
work published in 1981, but with an
important difference. The stars are taken
from the Hipparcos and Tycho
Catalogues, the result of four years worth
of all-sky scans by the European Space
Agency's Hipparcos satellite. Published
in 1997, it replaced "all previous surveys
as a reliable census of the positions and
brightnesses of one million brightest
stars."
The stars in this edition have a visual
magnitude of 8.5 or brighter. The total
number of single, double, or variable
stars equals 81,312 in this atlas. Each
chart has a legend containing symbols for
deep-sky objects; galaxies are displayed
in the same perspective as they are seen
in the sky. Open clusters must have a
total magnitude of at least 8.5; “Globular
clusters, typically more condensed, are
plotted to magnitude 11. Galaxies are
shown to a cutoff of about magnitude 13
(in blue light) and planetary nebulae to 14
(in blue light).”
The four indices are for constellations,
Messier objects, named stars, and
“miscellaneous”. There is also a plastic
overlay and a chart key.
Some of the star charts bear an eerie
resemblance to sea charts that show
gradations in differing shades of blue that
approximate ocean depths, with darkest
blue reserved for the deepest parts. “The
Milky Way is portrayed with four shades
of blue that represent approximate
brightness levels. The deepest blues are
the brightest features of our galaxy, best
appreciated under country skies far away
from city lights.”
Galaxies stand out; they are delineated in
red. The Virgo cluster of galaxies spills
over into Coma Berenices and is very evident.