SUNCLOCK(1) UNIX System V SUNCLOCK(1)
NAME
sunclock - show illuminated portion of Earth
SYNOPSIS
sunclock [ options ]
DESCRIPTION
sunclock is an X11 application that displays a map of the Earth and
indicates the illuminated portion of the globe by drawing sunlit areas
dark on light, night areas as light on dark. It also displays the
current date and time.
OPTIONS
The program does not use the X Toolkit, and hence only those options
explicitly enumerated below may be used. Neither are any resources used.
-version
Show program version and patch level, and then exit.
-display dispname
Give the name of the X server to contact.
-iconic
Start iconic. Usually you will want to specify this option.
-geometry +x+y
Specify the position of the window. Only the position is used; any
size information given is ignored.
-icongeometry +x+y
Specify the position of the icon. Only the position is used; any
size information given is ignored.
HOW IT WORKS
sunclock calculates the position of the Sun using the algorithm in
chapter 18 of:
Astronomical Formulae for Calculators by Jean Meeus, Third Edition,
Richmond: Willmann-Bell, 1985.
and Mercator projects the illuminated area onto map image. The Sun's
position is calculated to better than one arc-second in accuracy.
BUGS
The maps are not rescaled if you resize the open window or icon. (I
don't want to have to store a vector database for the map.) The program
contravenes section 4.1.9 of the ICCCM in that its icon window is a fixed
size, and any WM_ICON_SIZE property of the root window is ignored.
The illuminated area shown is the area which would be sunlit if the Earth
had no atmosphere. The actual illuminated area is larger because of
atmospheric refraction and twilight.
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SUNCLOCK(1) UNIX System V SUNCLOCK(1)
AUTHOR
John Mackin, Basser Department of Computer Science, University of Sydney,
Sydney, Australia; <john@cs.su.oz.AU>. Based on a Suntools program by
John Walker, Autodesk, Inc.; <kelvin@acad.uu.NET>.
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