.TH sunclock "" "" "X Application"
.PC "Show what the time really is"
.fi
\fBsunclock
[\-display \fIserver\^\fB]
[\-iconic]
[\-geometry \fI+x+y\^\fB]
[\-icongeometry \fI+x+y\^\fB]
[\-version]\fR
.PP
The X application
.B sunclock
displays a map of the Earth that shows the sunlight portions
in white on black and the dark portions in black on white.
It also displays the current date and time in both your local time
and UTC.
(For details on UTC and how it differs from GMT, see the overview article on
.B time
in the \*(CO Lexicon.)
.PP
The program does not use the X Toolkit; therefore,
.B sunclock
does not use resources, and it recognizes only the following
command-line options:
.IP "\fB\-display \fIserver\fR"
Name the X server to contact.
.IP \fB\-iconic\fR
Start in icon form.
Usually, you will want to use this option.
.IP "\fB\-geometry \fI+x+y\fR"
Give the position of the window, in pixels.
Note that unlike the
.B geometry
option used by the
.B Xt
toolkit,
.B sunclock
recognizes only the position:
it ignores all size information.
.IP "\fB\-icongeometry \fI+x+y\fR"
Give the position of the icon, in pixels.
Note that unlike the
.B icongeometry
option used by the
.B Xt
toolkit,
.B sunclock
recognizes only the position:
it ignores all size information.
.IP \fB\-version\fR
Display the program's version and patch level, then exit.
.SH "How It Works"
.B sunclock
calculates the position of the Sun using the algorithm given in chapter 18 of
.I "Astronomical Formulae for Calculators,"
third edition, by Jean Meeus (Richmond, Va, Willmann-Bell, 1985).
and Mercator projects the illuminated area onto the map image.
The Sun's position is calculated to better than one arc-second in accuracy.
.PP
The illuminated area shown is the area that would be sunlit
if the Earth had no atmosphere.
The actual illuminated area is
larger because of atmospheric refraction and twilight.
.SH "See Also"
.B
oclock,
X,
X applications,
xclock
.R
.br
\*(CO Lexicon:
.B
time (overview)
.R
.SH Notes
.B xclock
does not rescale its maps 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
the program ignores any
.B WM_ICON_SIZE
property of the root window.
.PP
.II "Mackin, John"
.B sunclock
was written by
John Mackin, Basser Department of Computer Science, University of Sydney,
Sydney, Australia (john@cs.su.oz.AU).
.II "Walker, John"
It is based on a Suntools program by John Walker, Autodesk, Inc.
(kelvin@acad.uu.NET).
.II "Pulley, Harry"
It was ported to \*(CO by Harry C. Pulley, IV.
