Astro-satpass

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lib/Astro/Coord/ECI.pm  view on Meta::CPAN

        @{[__PACKAGE__]}.
EOD

    my $want = shift;
    defined $want and $want = $want ? 1 : 0;

    my $denom = $body->mean_angular_velocity -
	$self->mean_angular_velocity;
##  my $retro = $denom >= 0 ? 0 : 1;
    ($denom = abs ($denom)) < 1e-11 and croak <<eod;
Error - The next_azimuth() method will not work for geosynchronous
        bodies.
eod

    my $apparent = TWOPI / $denom;
    my $begin = $self->universal;
    my $delta = floor( $apparent / 8 );
    my $end = $begin + $delta;

    my $begin_angle = mod2pi(
	( $self->azel( $body->universal( $begin ) ) )[0] - $azimuth );

lib/Astro/Coord/ECI.pm  view on Meta::CPAN

The returns are the time of the meridian passage, and an indicator which
is true if the passage is above the observer (i.e. local noon if the
C<$body> represents the Sun), or false if below (i.e. local midnight if
the C<$body> represents the Sun). If called in scalar context, you get
the time only.

The current time of both C<$coord> and C<$body> objects are left at the
returned time.

The algorithm is by successive approximation. It will croak if the
period of the C<$body> is close to synchronous, and will probably not
work well for bodies in highly eccentric orbits. The calculation is to
the nearest second, and the time returned is the first even second after
the body crosses the meridian.

=item ( $time, $above ) = $coord->next_meridian( $want )

This method calculates the next meridian passage of the C<$coord> object
over (or under) the location specified by the C<$coord> object's
C<station> attribute.

lib/Astro/Coord/ECI.pm  view on Meta::CPAN

The returns are the time of the meridian passage, and an indicator which
is true if the passage is above the observer (i.e. local noon if the
C<$coord> object represents the Sun), or false if below (i.e. local
midnight if the C<$coord> object represents the Sun). If called in
scalar context, you get the time only.

The current time of both C<$coord> and its C<station> are left at the
returned time.

The algorithm is by successive approximation. It will croak if the
period of the C<$body> is close to synchronous, and will probably not
work well for bodies in highly eccentric orbits. The calculation is to
the nearest second, and the time returned is the first even second after
the body crosses the meridian.

=cut

sub next_meridian {
    my ( $self, $body, $want ) = _expand_args_default_station( @_ );
    ref $self or croak <<'EOD';
Error - The next_meridian() method may not be called as a class method.

lib/Astro/Coord/ECI.pm  view on Meta::CPAN

Error - The argument to next_meridian() must be a subclass of
        @{[__PACKAGE__]}.
EOD

    defined $want and $want = $want ? 1 : 0;

    my $denom = $body->mean_angular_velocity -
	$self->mean_angular_velocity;
    my $retro = $denom >= 0 ? 0 : 1;
    ($denom = abs ($denom)) < 1e-11 and croak <<'EOD';
Error - The next_meridian() method will not work for geosynchronous
        bodies.
EOD

    my $apparent = TWOPI / $denom;
    my $begin = $self->universal;
    my $delta = floor ($apparent / 16);
    my $end = $begin + $delta;

    my ($above, $opposite) =
	mod2pi (($body->universal($begin)->geocentric)[1]

lib/Astro/Coord/ECI/TLE.pm  view on Meta::CPAN

# http://celestrak.org/NORAD/documentation/spacetrk.pdf

=item @passes = $tle->pass ($station, $start, $end, \@sky)

This method returns passes of the body over the given station between
the given start end end times. The \@sky argument is background bodies
to compute appulses with (see note 3).

A pass is detected by this method when the body sets. Unless
C<PASS_VARIANT_TRUNCATE> (see below) is in effect, this means that
passes are not usefully detected for geosynchronous or
near-geosynchronous bodies, and that passes where the body sets after
the C<$end> time will not be detected.

All arguments are optional, the defaults being

 $station = the 'station' attribute of the invocant
 $start = time()
 $end = $start + 7 days
 \@sky = []

The return is a list of passes, which may be empty. Each pass is

lib/Astro/Coord/ECI/TLE.pm  view on Meta::CPAN

clock time versus not setting it. Your mileage may, of course, vary.
This has no effect unless the C<visible> attribute is false.

* C<PASS_VARIANT_TRUNCATE> - Specifies that any pass in progress at the
beginning or end of the calculation interval is to be truncated to the
interval. If the calculation interval starts with the body already above
the horizon, the initial event of that pass will be C<PASS_EVENT_START>
rather than C<PASS_EVENT_RISE>. Similarly, if the calculation interval
ends with the body still above the horizon, the final event of that pass
will be C<PASS_EVENT_END>. With this variant in effect, 'passes' will be
computed for synchronous satellites. This variant is to be considered
B<experimental.>

* C<PASS_VARIANT_BRIGHTEST> - Specifies that the the moment the
satellite is brightest be computed as part of the pass statistics. The
computation is to the nearest second, and is not done if
C<PASS_VARIANT_NO_ILLUMINATION> is set, the satellite has no intrinsic
magnitude set, or the satellite is not illuminated during the pass.

* C<PASS_VARIANT_NONE> - Specifies that no pass variant processing take
place.

t/eci.t  view on Meta::CPAN

# azel
# Tests: azel() (and geodetic(), geocentric(), and eci())

# Book solution from
# http://www.satcom.co.uk/article.asp?article=1

note <<'EOD';

In the following three tests the tolerance is degraded because the
book solution is calculated by http://www.satcom.co.uk/article.asp?article=1
which apparently assumes an exactly synchronous orbit. Their exact
altitude assumption is undocumented, as is their algorithm. So the
tests are really more of a sanity check.

EOD

{
    my $time = greg_time_gm( 0, 0, 5, 27, 7, 2005 );
    my $sta = Astro::Coord::ECI->new( ellipsoid => 'GRS80' )->
	geodetic( deg2rad( 38 ), deg2rad( -80 ), 1 );
    my $sat = Astro::Coord::ECI->new( ellipsoid => 'GRS80' )->