NAME

Astro::Catalog::Query - Base class for Astro::Catalog query objects

SYNOPSIS

  use base qw/Astro::Catalog::Query/;

DESCRIPTION

This class forms a base class for all the query classes provided in the "Astro::Catalog" distribution (eg "Astro::Catalog::GSC::Query").

METHODS

Constructor

new

Create a new instance from a hash of options

    $q = new Astro::Catalog::Query(
        Coords    => new Astro::Coords(),
        Radius    => $radius,
        Bright    => $magbright,
        Faint     => $magfaint,
        Sort      => $sort_type,
        Number    => $number_out);

returns a reference to an query object. Must only called from sub-classed constructors.

RA and Dec are also allowed but are deprecated (since with only RA/Dec the coordinates must always be supplied as J2000 space-separated sexagesimal format).

Accessor Methods

query_options

Hash representing the query options to be used to query the catalog server. This keys in this hash are restricted by the subclass. Some keys are not usable by all catalogues.

Returns a copy of the options hash when.

    %options = $q->query_options();

Note that the hash keys included here are not necessarily the keys used to form a remote query.

If an argument is supplied, the value for that option is returned if the option is supported.

    $ra = $q->query_options("ra");

Values can not be set directly. Please use the provided accessor methods.

RA

Return (or set) the current target R.A. defined for the query

    $ra = $usno->ra();
    $usno->ra($ra);

where $ra should be a string of the form "HH MM SS.SS", e.g. 21 42 42.66

Dec

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

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

Target

Instead of querying by R.A. and Dec., you may also query it by object name. Return (or set) the current target object defined for the USNO-A2.0 query, will query SIMBAD for object name resolution.

    $ident = $usno->target();
    $usno->target("HT Cas");

using an object name will override the current R.A. and Dec settings for the Query object (if currently set) and the next querydb() method call will query using this identifier rather than any currently set co-ordinates.

Radius

The radius to be searched for objects around the target R.A. and Dec in arc minutes, the radius defaults to 5 arc minutes.

    $radius = $query->radius();
    $query->radius(20);

Faint

Set (or query) the faint magnitude limit for inclusion on the results

    $faint = $query->faint();
    $query->faint(50);

Bright

Set (or query) the bright magnitude limit for inclusion on the results

    $faint = $query->bright();
    $query->bright(2);

Sort

Set or query the order in which the stars are listed in the catalogue

    $sort = $query->sort();
    $query->sort('RA');

valid options are RA, DEC, RMAG, BMAG, DIST (distance to centre of the requested field) and POS (the position angle to the centre of the field).

Number

The number of objects to return, defaults to 2000 which should hopefully be sufficent to return all objects of interest. This value should be increased if a (very) large sample radius is requested.

    $num = $query->number();
    $query->nout(100);

General Methods

configure

Configures the object, takes an options hash as an argument

    $dss->configure(%options);

Does nothing if the array is not supplied.

COPYRIGHT

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>, Tim Jenness <tjenness@cpan.org>