Astro::FITS::HdrTrans::UIST - UKIRT UIST translations

  use Astro::FITS::HdrTrans::UIST;

  %gen = Astro::FITS::HdrTrans::UIST->translate_from_FITS( %hdr );

 $Id$

package Astro::FITS::HdrTrans::UIST;

use 5.006;
use warnings;
use strict;
use Carp;

# Inherit from UKIRTNew
use base qw/ Astro::FITS::HdrTrans::UKIRTNew /;

use vars qw/ $VERSION /;

$VERSION = "1.50";

# for a constant mapping, there is no FITS header, just a generic
# header that is constant
my %CONST_MAP = (
                 NSCAN_POSITIONS     => 1,
                 SCAN_INCREMENT      => 1,
                );

# NULL mappings used to override base class implementations
my @NULL_MAP = qw/ DETECTOR_INDEX /;

# unit mapping implies that the value propogates directly
# to the output with only a keyword name change

my %UNIT_MAP = (
                RA_SCALE             => "CDELT2",
                 
                # UIST specific
                GRATING_NAME         => "GRISM",

                # Not imaging
                GRATING_DISPERSION   => "DISPERSN",
                GRATING_NAME         => "GRISM",
                GRATING_ORDER        => "GRATORD",
                GRATING_WAVELENGTH   => "CENWAVL",
                SLIT_ANGLE           => "SLIT_PA",
                SLIT_WIDTH           => "SLITWID",

                # MICHELLE compatible
                CHOP_ANGLE           => "CHPANGLE",
                CHOP_THROW           => "CHPTHROW",
                DETECTOR_READ_TYPE   => "DET_MODE",
                NUMBER_OF_READS      => "NREADS",
                OBSERVATION_MODE     => "INSTMODE",
                POLARIMETRY          => "POLARISE",
                SLIT_NAME            => "SLITNAME",

                # CGS4 + MICHELLE + WFCAM
                CONFIGURATION_INDEX  => 'CNFINDEX',
               );


# Create the translation methods
__PACKAGE__->_generate_lookup_methods( \%CONST_MAP, \%UNIT_MAP, \@NULL_MAP );

sub this_instrument {
  return "UIST";
}

sub to_DEC_SCALE {
  my $self = shift;
  my $FITS_headers = shift;
  my $return;
  if ( $self->to_OBSERVATION_MODE($FITS_headers) eq 'imaging' ) {
    $return = $FITS_headers->{CDELT1};
  } else {
    $return = $FITS_headers->{CDELT3};
  }
  return $return;
}

sub from_DEC_SCALE {
  my $self = shift;
  my $generic_headers = shift;

  # Can calculate the pixel size...
  my $scale = abs( $generic_headers->{DEC_SCALE} );
  $scale *= 3600;
  my %result = ( PIXLSIZE => $scale );

  # and either CDELT1 or CDELT3.
  my $ckey = 'CDELT3';
  if ( $generic_headers->{OBSERVATION_MODE} eq 'imaging' ) {
    $ckey = 'CDELT1';
  }
  $result{$ckey} = $generic_headers->{DEC_SCALE};
  return %result;
}

sub to_ROTATION {
  my $self = shift;
  my $FITS_headers = shift;
  my $rotation;
  if ( exists( $FITS_headers->{PC1_1} ) && exists( $FITS_headers->{PC2_1}) ) {
    my $pc11;
    my $pc21;
    if ( exists ($FITS_headers->{PC3_2} ) && exists( $FITS_headers->{PC2_2} ) ) {

      # We're in spectroscopy mode.
      $pc11 = $FITS_headers->{PC3_2};
      $pc21 = $FITS_headers->{PC2_2};
    } else {

      # We're in imaging mode.
      $pc11 = $FITS_headers->{PC1_1};
      $pc21 = $FITS_headers->{PC2_1};
    }
    my $rad = 57.2957795131;
    $rotation = $rad * atan2( -$pc21 / $rad, $pc11 / $rad ) + 90.0;

  } elsif ( exists $FITS_headers->{CROTA2} ) {
    $rotation =  $FITS_headers->{CROTA2} + 90.0;
  } else {
    $rotation = 90.0;
  }
  return $rotation;
}

sub to_X_REFERENCE_PIXEL{
  my $self = shift;
  my $FITS_headers = shift;
  my $xref;
  if ( exists $FITS_headers->{CRPIX1} ) {
    $xref = $FITS_headers->{CRPIX1};
  } elsif ( exists $FITS_headers->{RDOUT_X1} &&
            exists $FITS_headers->{RDOUT_X2} ) {
    my $xl = $FITS_headers->{RDOUT_X1};
    my $xu = $FITS_headers->{RDOUT_X2};
    $xref = $self->nint( ( $xl + $xu ) / 2 );
  } else {
    $xref = 480;
  }
  return $xref;
}

sub from_X_REFERENCE_PIXEL {
  my $self = shift;
  my $generic_headers = shift;
  return ( "CRPIX1", $generic_headers->{"X_REFERENCE_PIXEL"} );
}

sub to_Y_REFERENCE_PIXEL{
  my $self = shift;
  my $FITS_headers = shift;
  my $yref;
  if ( exists $FITS_headers->{CRPIX2} ) {
    $yref = $FITS_headers->{CRPIX2};
  } elsif ( exists $FITS_headers->{RDOUT_Y1} &&
            exists $FITS_headers->{RDOUT_Y2} ) {
    my $yl = $FITS_headers->{RDOUT_Y1};
    my $yu = $FITS_headers->{RDOUT_Y2};
    $yref = $self->nint( ( $yl + $yu ) / 2 );
  } else {
    $yref = 480;
  }
  return $yref;
}

sub from_Y_REFERENCE_PIXEL {
  my $self = shift;
  my $generic_headers = shift;
  return ( "CRPIX2", $generic_headers->{"Y_REFERENCE_PIXEL"} );
}

1;