Insert
the installation CD and run setup.exe. Follow the instructions until set-up is
complete. Astrolabium Screen Saver should then appear under Programs
in the Start menu. Simply click on the item to run the screen saver. Because
it is a screen saver, however, it will disappear as soon as you move the mouse.
In
order for the screen saver to appear automatically on your screen, your
computer’s display properties need to be adjusted. There are two possible ways
of doing this:
1)
Open the Control Panel and
select Display. Click on Screen Saver and select the Astrolabium
Screen Saver.
2)
Right click with the mouse on the
desktop. From the Popup menu that appears select Properties. The Display
Properties menu appears. Click on Screen Saver and select the
Astrolabium Screen Saver.
It
is also possible to vary the parameters of the Astrolabium Screen Saver from
this screen.
The
parameters for the town of Mestre for example are: latitude: 43.5047,
longitude: -12.2525, STZ = -1.
On
the screen, however, they appear in sexagesimal form, i.e.: latitude: 43° 30’
16.92”, longitude: -12° 15’ 9”.
If
daylight saving time is in operation, click on DST (dst = 1).
All
the planets, the moon and the sun are shown. The various phases of Mercury,
Venus, Mars and the moon are also shown as well as the vernal point g.
The
information is updated every second.
The
sky is pale blue during the day, and then changes colour gradually after sunset
until the sun reaches an angle of 18° below the horizon, at which point it
turns black. The three outer circles show three different altitudes of the sun,
or of any other star, below the horizon: -6° (cyan blue), -12° (blue) and –18°
(dark blue).
The
figure-of-eight curve, the lemniscate for average time (analemma), shows how
the sun’s position at 12 noon varies according to the season. The lemniscate is
subdivided into 12 parts, each of which represents a month of the year. The
sun’s exact position is indicated by a circle of the same dimensions as the
sun’s disk. At 12pm, the sun sits precisely on the circle.
When
the sun hits the north-south axis precisely it is 12pm local time, or solar
noon.
The
solstice lines are also shown, along with those of the equator and the
ecliptic.
The
grid lines on the astrolabe cover the section of sky that is above the horizon.
The
altitude circles above the horizon are shown at ten-degree intervals. Those
below the horizon are shown at six-degree intervals. The azimuth lines, arcs of
a circle at ten-degree intervals, converge at the zenith.
The
position of the North Pole is indicated by the pole star.
That
of the South Pole is highlighted by a red dot.
Astrolabium
Screen Saver is a simplified version of The Astrolabium, a sophisticated
professional program which supplies much more information and simulates cosmic
events such as precession, the comparative size of the planets, the apparent
position of Jupiter’s satellites as discovered by Galileo, Saturn’s rings with
the Cassini division etc. It allows the user to print out a chart of the
heavens as well as a grid of the azimuths and the almucantarats for the
production of a traditional metal astrolabe.
Both
programs are the result of a father-son team effort. We have put our initials
together to give the acronym RAWA.
The
programme was produced with the almost exclusive use of spherical trigonometry
in Visual Basic.
Astrolabium
Screen Saver is the demo version of a freeware programme. Use of the
product is permitted but any sale thereof is strictly forbidden by law. The
authors own the intellectual property rights to the programme. They take no
responsibility for any malfunctions or any consequences arising from improper
use of the same.
Riccardo
Anselmi & Andrea William Anselmi
Frazione
Tenso 31
11027
Saint-Vincent (AO)
Italy
E-mail:
riccardo.anselmi@libero.it
Web: http://digilander.iol.it/sundials