/ 
Astro-Coords-0.05
River stage one • 4 direct dependents • 5 total dependents
/ Astro::Coords::Interpolated

NAME

Astro::Coords::Interpolated - Specify astronomical coordinates using two reference positions

SYNOPSIS

$c = new Astro::Coords::Elements( elements => \%elements );

DESCRIPTION

This class is used by Astro::Coords for handling coordinates for moving sources specified as two coordinates at two epochs.

METHODS

Constructor

new

Instantiate a new object using the supplied options.

  $c = new Astro::Coords::Interpolated( ra1 => '05:22:56',
					dec1 => '-26:20:44.4',
					mjd1 => 52440.5,
					ra2 => '05:23:56',
					dec2 => '-26:20:50.4',
					mjd2 => 52441.5,
					units =>
				      );

Returns undef on error. The positions are assumed to be apparent RA/Dec. Units are optional (see Astro::Coords::Equatorial).

Accessor Methods

ra1

Apparent Right Ascension of first reference position. Defaults to radians.

$ra = $c->ra1( %opts );

Type of returned value is controlled with the same options as defined in Astro::Coords::Equatorial.

dec1

Apparent declination of first reference position. Default is to return it in radians.

$dec = $c->dec1( format => "sexagesimal" );
mjd1

Time (MJD) when the first reference position was valid.

ra2

Apparent Right Ascension of second reference position. Defaults to radians.

$ra = $c->ra2( %opts );

Type of returned value is controlled with the same options as defined in Astro::Coords::Equatorial.

dec2

Apparent declination of second reference position. Default is to return it in radians.

$dec = $c->dec2( format => "sexagesimal" );
mjd2

Time (MJD) when the second reference position was valid.

General Methods

array

Return back 11 element array with first element containing the string "INTERP", the next ten elements as undef.

This method returns a standardised set of elements across all types of coordinates.

The original design did not contain this type of coordinate specification and so the array returned can not yet include it. Needs more work to integrate into the other coordinate systems.

type

Returns the generic type associated with the coordinate system. For this class the answer is always "INTERP".

This is used to aid construction of summary tables when using mixed coordinates.

It could be done using isa relationships.

stringify

Stringify overload. Just returns the type.

summary

Return a one line summary of the coordinates. In the future will accept arguments to control output.

$summary = $c->summary();
_apparent

Return the apparent RA and Dec (in radians) for the current coordinates and time.

($ra,$dec) = $c->_apparent();

Returns empty list on error.

Apparent RA/Dec is obtained by linear interpolation from the reference positions. If the requested time lies outside the reference times the position will be extrapolated.

NOTES

Usually called via Astro::Coords. This is the coordinate style used by SCUBA instead of using orbital elements.

Apparent RA/Decs suitable for use in this class can be obtained from http://ssd.jpl.nasa.gov/.

SEE ALSO

Astro::Coords::Elements

REQUIREMENTS

Does not use any external SLALIB routines.

AUTHOR

Tim Jenness <t.jenness@jach.hawaii.edu>

COPYRIGHT

Copyright (C) 2001-2002 Particle Physics and Astronomy Research Council. All Rights Reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.