sunclock

     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.

     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>.