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package Astro::DSS;

# ---------------------------------------------------------------------------

#+ 
#  Name:
#    Astro::DSS

#  Purposes:
#    Perl wrapper for the Digital Sky Survey (DSS)

#  Language:
#    Perl module

#  Description:
#    This module wraps the DSS online database.

#  Authors:
#    Alasdair Allan (aa@astro.ex.ac.uk)

#  Revision:
#     $Id: DSS.pm,v 1.7 2003/02/21 18:52:15 aa Exp $

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

#-

# ---------------------------------------------------------------------------

=head1 NAME

Astro::DSS - An Object Orientated interface to the Digital Sky Survey

=head1 SYNOPSIS

  $dss = new Astro::DSS( RA        => $ra,
                         Dec       => $dec,
                         Target    => $object_name,
                         Equinox   => $equinox,
                         Xsize     => $x_arcmin,
                         Ysize     => $y_arcmin,
                         Survey    => $dss_survey,
                         Format => $type );

  my $file_name = $dss->querydb();

=head1 DESCRIPTION

Stores information about an prospective DSS query and allows the query to
be made, returning a filename pointing to the file returned.

The object will by default pick up the proxy information from the HTTP_PROXY 
and NO_PROXY environment variables, see the LWP::UserAgent documentation for
details.

It will save returned files into the ESTAR_DATA directory or to TMP if
the ESTAR_DATA environment variable is not defined.

=cut

# L O A D   M O D U L E S --------------------------------------------------

use strict;
use vars qw/ $VERSION /;

use LWP::UserAgent;
use Net::Domain qw(hostname hostdomain);
use File::Spec;
use Carp;

'$Revision: 1.7 $ ' =~ /.*:\s(.*)\s\$/ && ($VERSION = $1);

# C O N S T R U C T O R ----------------------------------------------------

=head1 REVISION

$Id: DSS.pm,v 1.7 2003/02/21 18:52:15 aa Exp $

=head1 METHODS

=head2 Constructor

=over 4

=item B<new>

Create a new instance from a hash of options

  $dss = new Astro::DSS( RA        => $ra,
                         Dec       => $dec,
                         Target    => $object_name,
                         Equinox   => $equinox,
                         Xsize     => $x_arcmin,
                         Ysize     => $y_arcmin,
                         Survey    => $dss_survey,
                         Format    => $image_type );

returns a reference to an DSS query object.

=cut

sub new {
  my $proto = shift;
  my $class = ref($proto) || $proto;

  # bless the query hash into the class
  my $block = bless { OPTIONS   => {},
                      URL       => undef,
                      QUERY     => undef,
                      USERAGENT => undef,
                      DATADIR   => undef }, $class;