/ 
Astro-Catalog-2.1.2
River stage one • 2 direct dependents • 2 total dependents
/ Astro::Catalog::Star

NAME

Astro::Catalog::Star - A generic star object in a stellar catalogue.

SYNOPSIS

$star = new Astro::Catalog::Star( ID         => $id, 
                                  RA         => $ra,
                                  Dec        => $dec,
                                  Magnitudes => \%magnitudes,
                                  MagErr     => \%mag_errors,
                                  Colours    => \%colours,
                                  ColErr     => \%colour_errors,
                                  Quality    => $quality_flag,
                                  Field      => $field,
                                  GSC        => $in_gsc,
                                  Distance   => $distance_to_centre,
                                  PosAngle   => $position_angle,
                                  X          => $x_pixel_coord,
                                  Y          => $y_pixel_coord );

DESCRIPTION

Stores generic meta-data about an individual stellar object from a catalogue.

If the catalogue has a field center the Distance and Position Angle properties should be used to store the direction to the field center, e.g. a star from the USNO-A2 catalogue retrieived from the ESO/ST-ECF Archive will have these properties.

REVISION

$Id: Star.pm,v 1.6 2002/03/29 17:40:17 aa Exp $

METHODS

Constructor

new

Create a new instance from a hash of options

$star = new Astro::Catalog::Star( ID         => $id, 
                                  RA         => $ra,
                                  Dec        => $dec,
                                  Magnitudes => \%magnitudes,
                                  MagErr     => \%mag_errors,
                                  Colours    => \%colours,
                                  ColErr     => \%colour_errors,
                                  Quality    => $quality_flag,
                                  Field      => $field,
                                  GSC        => $in_gsc,
                                  Distance   => $distance_to_centre,
                                  PosAngle   => $position_angle,
                                  X          => $x_pixel_coord,
                                  Y          => $y_pixel_coord );

returns a reference to an Astro::Catalog::Star object.

Accessor Methods

id

Return (or set) the ID of the star

$id = $star->id();
$star->id( $id );
RA

Return (or set) the current object R.A.

$ra = $star->ra();
$star->ra( $ra );
Dec

Return (or set) the current target Declination defined for the DSS query

$dec = $dss->dec();
$dss->dec( $dec );

where $dec should be a string of the form "+-HH MM SS.SS", e.g. +43 35 09.5 or -40 25 67.89

Magnitudes

Set the UBVRIHK magnitudes of the object, takes a reference to a hash of magnitude values

my %mags = ( B => '16.5', V => '15.4', R => '14.3' );
$star->magnitudes( \%mags );

additional calls to magnitudes() will append, not replace, additional magnitude values, magnitudes for filters already existing will be over-written.

MagErr

Set the error in UBVRIHK magnitudes of the object, takes a reference to a hash of error values

my %mag_errors = ( B => '0.3', V => '0.1', R => '0.4' );
$star->magerr( \%mag_errors );

additional calls to magerr() will append, not replace, additional error values, errors for filters already existing will be over-written.

Colours

Set the colour values for the object, takes a reference to a hash of colours

my %cols = ( 'B-V' => '0.5', 'B-R' => '0.4' );
$star->colours( \%cols );

additional calls to colours() will append, not replace, colour values, altough for colours which already have defined values, these values will be over-written.

ColErr

Set the colour error values for the object, takes a reference to a hash of colour errors

my %col_errors = ( 'B-V' => '0.02', 'B-R' => '0.05' );
$star->colerr( \%col_errors );

additional calls to colerr() will append, not replace, colour error values, altough for errors which already have defined values, these values will be over-written.

what_filters

Returns a list of the filters for which the object has defined values.

@filters = $star->what_filters();
$num = $star->what_filters();

if called in a scalar context it will return the number of filters which have defined magnitudes in the object.

what_colours

Returns a list of the colours for which the object has defined values.

@colours = $star->what_colours();
$num = $star->what_colours();

if called in a scalar context it will return the number of colours which have defined values in the object.

get_magnitude

Returns the magnitude for the supplied filter if available

$magnitude = $star->get_magnitude( 'B' );
get_errors

Returns the error in the magnitude value for the supplied filter if available

$mag_errors = $star->get_errors( 'B' );
get_colour

Returns the value of the supplied colour if available

$colour = $star->get_colour( 'B-V' );
get_colourerror

Returns the error in the colour value for the supplied colour if available

$col_errors = $star->get_colourerr( 'B-V' );
quality

Return (or set) the quality flag of the star

$quality = $star->quailty();
$star->quality( 0 );

for example for the USNO-A2 catalogue, 0 denotes good quality, and 1 denotes a possible problem object. In the generic case any flag value, including a boolean, could be used.

field

Return (or set) the field parameter for the star

$field = $star->field();
$star->field( '0080' );
gsc

Return (or set) the GSC flag for the object

$gsc = $star->gsc();
$star->gsc( 'TRUE' );

the flag is TRUE if the object is known to be in the Guide Star Catalogue, and FALSE otherwise.

distance

Return (or set) the distance from the field centre

$distance = $star->distance();
$star->distance( '0.009' );

e.g. for the USNO-A2 catalogue.

posangle

Return (or set) the position angle from the field centre

$position_angle = $star->posangle();
$star->posangle( '50.761' );

e.g. for the USNO-A2 catalogue.

x

Return (or set) the X pixel co-ordinate of the star

$x = $star->x();
$star->id( $x );
y

Return (or set) the Y pixel co-ordinate of the star

$y = $star->y();
$star->id( $y );

General Methods

configure

Configures the object from multiple pieces of information.

$star->configure( %options );

Takes a hash as argument with the list of keywords.

freeze

Method to return a blessed reference to the object so that we can store ths object on disk using Data::Dumper module.

COPYRIGHT

Copyright (C) 2001 University of Exeter. All Rights Reserved.

This program was written as part of the eSTAR project and is free software; you can redistribute it and/or modify it under the terms of the GNU Public License.

AUTHORS

Alasdair Allan <aa@astro.ex.ac.uk>,