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MoonPhase.pm  view on Meta::CPAN

    0  New Moon
    1  First quarter
    2  Full Moon
    3  Last quarter

The remaining values in C<@times> indicate subsequent phases of the
moon (in ascending order by time).  If there are no phases of the moon
between C<$start> and C<$stop>, C<phaselist> returns the empty list.

Example:

    @name = ("New Moon", "First quarter", "Full moon", "Last quarter");
    ($phase, @times) = phaselist($start, $stop);

    while (@times) {
      printf "%-14s= %s\n", $name[$phase], scalar localtime shift @times;
      $phase = ($phase + 1) % 4;
    }

could produce the same output as the C<phasehunt> example above (given
the appropriate start & stop times).

=head1 ABOUT THE ALGORITHMS

The algorithms used in this program to calculate the positions of Sun and
Moon as seen from the Earth are given in the book I<Practical Astronomy
With  Your  Calculator>  by  B<Peter  Duffett-Smith,   Second   Edition,
Cambridge University Press, 1981>.  Ignore the word "Calculator" in the
title;  this  is  an  essential  reference  if  you're  interested  in
developing  software  which  calculates  planetary  positions, orbits,
eclipses, and  the  like.   If  you're  interested  in  pursuing  such
programming, you should also obtain:

I<Astronomical  Formulae for Calculators> by B<Jean Meeus, Third Edition,
Willmann-Bell, 1985>.  A must-have.

I<Planetary  Programs  and  Tables  from  -4000  to  +2800>  by  B<Pierre
Bretagnon  and Jean-Louis Simon, Willmann-Bell, 1986>.  If you want the
utmost  (outside  of  JPL)  accuracy  for  the  planets,  it's   here.

I<Celestial BASIC> by B<Eric Burgess, Revised Edition, Sybex, 1985>.  Very
cookbook oriented, and many of the algorithms are hard to dig  out  of
the turgid BASIC code, but you'll probably want it anyway.

Many of these references can be obtained from Willmann-Bell, P.O.  Box
35025,  Richmond,  VA 23235, USA.  Phone: (804) 320-7016.  In addition
to their own publications, they stock most of the standard  references
for mathematical and positional astronomy.

=head1 LICENCE

This  program is in the public domain: "Do what thou wilt shall be the
whole of the law".

=head1 AUTHORS

The moontool.c Release 2.0:

    A Moon for the Sun
    Designed and implemented by John Walker in December 1987,
    revised and updated in February of 1988.

Initial Perl transcription:

    Raino Pikkarainen, 1998
    raino.pikkarainen@saunalahti.fi

The moontool.c Release 2.4:

    Major enhancements by Ron Hitchens, 1989

Revisions:

    Brett Hamilton  http://simple.be/
    Bug fix, 2003
    Second transcription and bugfixes, 2004

    Christopher J. Madsen  http://www.cjmweb.net/
    Added phaselist function, March 2007