The best-known and most used, drawn astronomical atlas all over world
is the Becvar's Atlas Coeli Skalnate Pleso. In the coordinate system
referred to equinox 1950.0, all stars brighter than 7.75 magnitude are
included. The plotting is gradated by the magnitude in 16 large maps
of the atlas in the scale of 1° = 0.75 cm. There are specifically
marked the visual and spectroscopic double stars, multiple systems,
novae, supernovae and the brightest radio-sources; then globular and
galactic clusters, galaxies and extragalactic nebulae up to 13th
magnitude, the shapes of larger diffuse and dark nebulae, the shape of
the Milky Way, the Ecliptic, the Galactic equator and the
international borders of constellations. In contrast to other atlases,
Atlas Coeli is unique mainly because of the comprising of all planar
and diffuse sources being visible in a telescope of a diameter up to
20 cm. Due to this fact, the atlas became an ideal implement for,
e.g., the search for comets, i.e. for the work, which motivated the
creation of the atlas in part. The high perfection and clearness of
maps have been a cause, why the atlas has served as a necessary
implement at night work during not less than three decades, in the
professional observatories all over the world as well as at the
observations by the pretentious amateur astronomers.
The atlas was created on the basis of various astronomical catalogues
and about ten photographic atlases in the period of 1947-1948. It had
been created by a collective group associated in a large part by the
students, who had stayed practising at the Skalnate Pleso Observatory
during their holidays in these years. The whole conception and final
plottings of the atlas, including the descriptions, are completely the
work of Dr. A. Becvar himself. One can imagine the extension of the
work on the basis of the fact that there had to be drawn and checked,
by a dictate, the positions of about 35 000 objects into the
coordinate net. Including the overlapping regions, the sum of objects,
together with repeating of some on two or three maps, was almost 50
000. To plot each of the objects, there was necessary to choose one of
20 patterns in a stencil and to set the correct position of it. A lot
of hard work had been necessary to complete the basic Boss Star
Catalogue, which had been the most appropriate for this purpose that
time but, unfortunately, it had not been quite complete up to the
limiting magnitude of the plotted stars. Here, the need to read almost
a quarter of million of stars in the Henry Draper Star Catalogue
occurred, whereby there was not only necessary to identify the stars
absenting in the Boss catalogue, but also a re-calculation of their
positions taking into account the 50-year precession had to be done.
The atlas was, at first, published by the Czechoslovak Astronomical
Society in 1948. Soon after, the Catalogue followed. It was issued as
the second volume entitled the Atlas Coeli II. This contained various
data on more than 12 000 chosen objects (common stars up to the 6.25
magnitude only, the complete set, as in the maps, of other objects). A
six-colour improved version of the atlas was published by the
publishing house of the Czechoslovak Academy of Sciences in 1956. The
copy-right to publish the atlas outside the Czechoslovakia was bought
by the Harvardian "Sky Publishing Corporation", which advertized it in
its most spread popular scientific journal "Sky and Telescope". Under
copy-right of this corporation, the atlas has been published in a
series of editions: from a luxurious to a common, reduced in size,
with white stars on black background. By the requirement of the
author, royalties were met in the form of special astronomical
photographic plates, which significantly improved the efficiency of
the telescopes of the Skalnate Pleso Observatory for several next
years.
Dr. A. Becvar went on in the creation of atlases after he was retired
and lived in his birthplace in Brandys nad Labem. The result was
represented with three celestial atlases in a scale of 1° = 20 cm:
Atlas Eclipticalis (the celestial region between -30 and +30° of
declination on 32 maps), Atlas Borealis (the celestial region
northwards from declination of +30° on 24 maps), and Atlas Australis
(the celestial region southwards from declination of -30° on 24
maps). These atlases were considered for more specific purposes: the
choice of plotted stars is not limited by their brightness but by the
knowledge of their precise positions and proper motions; stellar
clusters and nebulae are not plotted but six-colour press is utilized
to distinguish 6 basic spectral classes of the stars. Also these
atlases have been spread all over the world by the Sky Publishing
Corporation. They have served mainly for the choice of reference stars
in the photographic astrometry and photometry. They were especially
utilized in the first phase of position measurements of artificial
satellite.
Perhaps, the most significant appreciation to Dr. A. Becvar
(1901-1962) for his atlases has been that a crater on the Moon was
named by his name. It is certainly worthy of admiration, when a unique
work, Atlas Coeli Skalnate Pleso, is recognized, in a certain topic,
to be the most used scientific aid during entire three decades. So
late as in 1981, a successful concurrent, Atlas Tirion Atlas 2000.0,
appeared. It will probably take the role of the Atlas Coeli after the
change of equinox, from 1950.0 to 2000.0. Tirion's atlas has its scale
enlarged to 1° = 1 cm. It consists of 26 instead of 16 maps, and it
contains stars up to 8.0 magnitude, i.e. about one third more than the
Becvar's atlas. A look at this concurrent, a generation younger and
from the era of computers, is perhaps the greatest compliment which
the Atlas Coeli Skalnate Pleso could ever receive: almost everything,
up to the marks for various types of objects, division of scales, and
the type of script are taken from the Atlas Coeli. What a little
improvement of this work was necessary after 30 years!