SOUTHERN ASTRONOMERS and AUSTRALIAN ASTRONOMY
S T A R C H A R T S
By HARLEY WOOD, Government Astronomer
Issued by
SYDNEY OBSERVATORY
and
THE DONOVAN ASTRONOMICAL TRUST
The following web pages were reproduced from a small
8-page A5-sized booklet that was issued by Sydney Observatory and
written by the then N.S.W. Government Astronomer, Dr. Harley Wood. It
is adaption of “Elementary Astronomy
for Service Use” produced in the
early 1940b.
Andrew James : 30th April 2005.
S T A R C H A R T S
The star charts show the whole sky on six sheets, the first and
last showing sections around the north and south poles.
The positions of the stars in the sky are specified by two numbers
which appear around the borders of the charts. The figures from 0 to
24, in hours and called right ascension, show which group of stars is
high in the sky at the time of observation and the figures which read
from 0° to 90° from the equator to the pole are called
declination. These correspond to longitude and latitude on the
surface of the Earth. For example the star Fomalhaut on Map II has a
right ascension 22h. 50m. and declination south 30°. The
following table shows the right ascension on the meridian at various
hours during the night at different times of the year and will
indicate which map to use. For example on February 5th at 10 p.m. the
right ascension on the meridian is 7h. Since this right ascension is
on Map III, this is the map to use.
RIGHT ASCENSION ON THE MERIDIAN.
Mid -
Date. 6 p.m. 8 p.m. 10 p.m. 0 a.m. 2 a.m. 4 a.m. 6 a.m.
night
Jan. 5 01 03 05 07 09 11 13
Feb. 5 03 05 07 09 11 13 15
Mar. 7 05 07 09 11 13 15 17
Apr. 6 07 09 11 13 15 17 19
May 7 09 11 13 15 17 19 21
June 6 11 13 15 17 19 21 23
July 7 13 15 17 19 21 23 01
Aug. 6 15 17 19 21 23 01 03
Sept.6 17 19 21 23 01 03 05
Oct. 6 19 21 23 01 03 05 07
Nov. 6 21 23 01 03 05 07 09
Dec. 6 23 01 03 05 07 09 11
In order to compare the maps with the sky, hold them up so that
the stars on the map will have the same orientation as the part of
the sky being examined. The end of the maps marked N will always be
to the north, and the higher right ascension towards the east. From
New South Wales or places of a similar latitude when you are looking
at the sky towards the north you will find it necessary to turn the
top of the maps downward. When looking towards the east the top
left-hand corner of the maps should be held downward, and when
looking to the west the top right-hand corner should be held
downward. It is necessary to use neighbouring maps to cover the whole
of the sky visible at one time. At the time quoted above if we look
eastward we will go out [*2] of the area represented on Map III and
enter the right-hand side of Map IV. The right ascension on the
meridian in the table shows also that part of the polar map which is
uppermost.
The constellations (or groups or stars) in the northern part of
the sky are mostly named from characters in Greek myths, such as
Orion and Perseus. The southern part of the sky, which could not be
seen by the Greeks, was divided up by astronomers and the sections
given names chosen by them, for example Telescopium (the
telescope).
The names of some of the more important stars have been derived
from Greek or Arab legend, others are named by a Greek letter and the
name of the constellation in which they are situated. Usually, though
not always, the letters are allotted nearly in order of brightness of
the stars in the constellation, for instance
α will be brighter than
β, and so on. So that you will be
able to use the names, a list of the Greek letters is given
below.
α Alpha |
ζ Zeta |
λ Lambda |
π Pi |
φ Phi |
β Beta |
η Eta |
μ mu |
ρ Rho |
χ Chi |
γ Gamma |
θ Theta |
ν Nu |
σ Sigma |
ψ Psi |
δ Delta |
ι Iota |
ξ Xi |
τ Tau |
ω Omega |
ε Epsilon |
κ Kappa |
ο Omicron |
υ Upsilon |
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The relative brightness of stars in the sky is designated by
numbers 1, 2, 3, etc., called magnitudes. The brightest stars have
magnitude 1, and the fainter the star the larger the magnitude
number. For example, Arcturus, Regulus and Spica on Map No. IV are
1st magnitude stars, while that star marked η to the right of Arcturus is a 3rd
magnitude star. Stars down to a little fainter than the sixth
magnitude can be seen with the naked eye. There are about 6,000 of
these over the whole sky, only half of which can be seen at any one
time. The maps are complete to magnitude 4.5. The shaded area
represents the approximate extent of the Milky Way.
Maps II to V show the ecliptic which is the path of the Sun and
near which the Moon and the planets will always be found.
The best way to begin learning the stars is to work outward on the
sky and the maps at the same time from a part of the sky you already
know or have managed to identify from the maps. The best
constellations to start with are Crux (the Southern Cross), Orion or
Scorpio. Suppose that Crux on the South Polar Map is already known
and we wish to work from this. In the line from δ in Crux to β in Crux and about twice this distance
further we see a bright star marked on the map — in Centaurus
and a little further another marked α. The same configuration can easily be
found in the sky. By thus connecting the stars in the sky and on the
map with imaginary geometrical figures it is easy to extend the known
region and after a few nights spent with the maps most of the
constellations and brighter stars visible at the time should be
easily recognizable.
CHARTS
NOTE: Text written as [*NN] is the page number in
the original document.
Last Update : 13th August 2012
Southern Astronomical Delights ©
(2012)
For any problems with this Website or Document please e-mail
me.
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