Astro-Sunrise

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Makefile.PL  view on Meta::CPAN

    VERSION_FROM   => 'lib/Astro/Sunrise.pm', # finds $VERSION
    ABSTRACT       => 'Perl extension for computing the sunrise/sunset on a given day',
    PREREQ_PM      => { # DateTime => '0.16',
                        POSIX        => 0,
                       'strict'      => 0,
                       'warnings'    => 0,
                       'Carp'        => 0,
                       'Math::Trig'  => 0, },
    AUTHOR         => [ 'Ron Hill <rkhill@firstlight.net>', 'Jean Forget <JFORGET@cpan.org>' ],
    LICENSE        => 'perl',
    # The oldest Perl to check Astro::Sunrise 0.92 is 5.6.2. Therefore, I guess Astro::Sunrise 0.93 and next will work in 5.6.2 too.
    MIN_PERL_VERSION => '5.6.2',
    BUILD_REQUIRES => { 'Test::More'         => '0',        # should be 'TEST_REQUIRES', except that ExtUtils::MakeMaker 6.5705 does not accept it
                        'ExtUtils::MakeMaker' => '6.57_02', # the first version to accept several authors in an arrayref
                           },
    META_MERGE       => {
       dynamic_config => 0,
       prereqs => {
         runtime => {
           recommends => {
               DateTime => '0.16',

doc/astronomical-notes.pod  view on Meta::CPAN

The text is often (but irregularly) updated on Github. There are
a French version and an English version. Since I am more at ease
discussing astronomical subjects in French, the English version
will lag behind the French one.

This text is an integral part of the module's distribution package.
So you can read it on web pages generated from CPAN
(for example L<https://metacpan.org>).
But it is not used during the module installation process.
So, I guess it will not appear in C<.deb> or C<.rpm> packages.

Although this text  is stored in the  L<Astro::Sunrise> repository, it
also  documents the  L<DateTime::Event::Sunrise> module,  which has  a
very  similar core  (astronomical computations)  and a  different API.
Since both  modules move at different  speeds, it may happen  that the
text you  are reading is  not synchronised with  the L<Astro::Sunrise>
module.

=head1 Why This Text? For Whom?

doc/astronomical-notes.pod  view on Meta::CPAN

=back

So this parameter combination is valid, but it is suspicious because it does not correspond
to a usual and mundane situation.

Q: After your explanation about the C<precise> parameter, is there a significant
difference between C<< alt => -0.833, upper_limb => 0 >> and
C<< alt => -0.583, upper_limb => 1 >>?

A: You guessed, it, there is nearly no difference. The example I will take is sunset
at Fairbanks on 3rd January 2020. I take 3rd January because it is the time of the year
when the sun is at its largest. According to Stellarium, the diameter is 32'32", so the
radius is 16'16". And I take Fairbanks, because near a polar circle, the course of the sun
at sunset is much shallower than near the equator. So, for 
C<< alt => -0.833, upper_limb => 0 >> the sunset occurs when the
center of the sun dist is at -50' and for 
C<< alt => -0.583, upper_limb => 1 >> it occurs when the center of the sun disk is at -51'16".
Stellarium gives 15:59:12 in the first case and 15:59:37 in the second case.
A meagre 25-second difference.

doc/astronomical-notes.pod  view on Meta::CPAN

are not significant?

A: Because I think that if there is an error, it will be the same error
for similar dates, that is, end-February and beg-March within a decade.
For instance, we may have a S<+45 s> bias on 2015-02-28 and a S<-50 s>
bias on 2015-10-28 and on 2050-02-28, but for all the dates similar
to 2015-02-28 in both a YYYY fashion and a MM-DD fashion, the bias will
be approximately the same as 2015-02-28. Maybe S<+43 s> or S<+46 s> instead
of S<+45 s>, but surely not S<-50 s>. So I can make comparisons with a
granularity of 1 second. By the way, the bias values I gave above are
complete guesses, they are not the result of a precise computation.

TO BE COMPLETED

=head1 Annex: Politically Correct Explanations

=head2 Policitally Correct Analemma

First, let us deal with observers located north of the Arctic Polar Circle.
They just have to know that the analemma and the pseudo-analemma cross the horizon
and are partly hidden by the ground. The hidden part, more or less important depending