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lib/Astro/FITS/HdrTrans/INGRID.pm  view on Meta::CPAN

    $dec = $self->dms_to_degrees( $sexa );
  }
  return $dec;
}

=item B<to_DEC_SCALE>

Sets the declination scale in arcseconds per pixel.  The C<CCDYPIXE>
and C<INGPSCAL> headers are used when both are defined.  Otherwise it
returns a default value of 0.2387 arcsec/pixel, assuming north is up.

=cut

sub to_DEC_SCALE {
  my $self = shift;
  my $FITS_headers = shift;
  my $decscale = 0.2387;

  # Assumes either x-y scales the same or the y corresponds to
  # declination.
  my $ccdypixe = $self->via_subheader( $FITS_headers, "CCDYPIXE" );
  my $ingpscal = $self->via_subheader( $FITS_headers, "INGPSCAL" );
  if ( defined $ccdypixe && defined $ingpscal ) {
    $decscale = $ccdypixe * 1000.0 * $ingpscal;
  }
  return $decscale;
}

=item B<to_DEC_TELESCOPE_OFFSET>

Sets the declination telescope offset in arcseconds.   It uses the
C<CAT-DEC> and C<DEC> keywords to derive the offset, and if either
does not exist, it returns a default of 0.0.

=cut

sub to_DEC_TELESCOPE_OFFSET {
  my $self = shift;
  my $FITS_headers = shift;
  my $decoffset = 0.0;
  if ( exists $FITS_headers->{"CAT-DEC"} && exists $FITS_headers->{DEC} ) {

    # Obtain the reference and telescope declinations positions measured in degrees.
    my $refdec = $self->dms_to_degrees( $FITS_headers->{"CAT-DEC"} );
    my $dec = $self->dms_to_degrees( $FITS_headers->{DEC} );

    # Find the offsets between the positions in arcseconds on the sky.
    $decoffset = 3600.0 * ( $dec - $refdec );
  }

  # The sense is reversed compared with UKIRT, as these measure the
  # place son the sky, not the motion of the telescope.
  return -1.0 * $decoffset
}

=item B<to_DETECTOR_READ_TYPE>

Returns the UKIRT-like detector type "STARE" or "NDSTARE" from the
FITS C<REDMODE> and C<NUMREADS> keywords.

This is guesswork at present.

=cut

sub to_DETECTOR_READ_TYPE {
  my $self = shift;
  my $FITS_headers = shift;
  my $read_type;
  my $readout_mode = $FITS_headers->{READMODE};
  my $nreads = $FITS_headers->{NUMREADS};
  if ( $readout_mode =~ /^mndr/i ||
       ( $readout_mode =~ /^cds/i && $nreads == 1 ) ) {
    $read_type = "STARE";
  } elsif ( $readout_mode =~ /^cds/i ) {
    $read_type = "NDSTARE";
  }
  return $read_type;
}

=item B<to_DR_RECIPE>

Returns the data-reduction recipe name.  The selection depends on the
values of the C<OBJECT> and C<OBSTYPE> keywords.  The default is
"QUICK_LOOK".  A dark returns "REDUCE_DARK", and an object's recipe is
"JITTER_SELF_FLAT".

=cut

# No clue what the recipe is apart for a dark and assume a dither
# pattern means JITTER_SELF_FLAT.
sub to_DR_RECIPE {
  my $self = shift;
  my $FITS_headers = shift;
  my $recipe = "QUICK_LOOK";

  # Look for a dither pattern.  These begin D-<n>/<m>: where
  # <m> represents the number of jitter positions in the group
  # and <n> is the number within the group.
  my $object = $FITS_headers->{OBJECT};
  if ( $object =~ /D-\d+\/\d+/ ) {
    $recipe = "JITTER_SELF_FLAT";
  } elsif ( $FITS_headers->{OBSTYPE} =~ /DARK/i ) {
    $recipe = "REDUCE_DARK";
  }

  return $recipe;
}

=item B<to_EQUINOX>

Returns the equinox in decimal years.  It's taken from the C<CAT-EQUI>
keyword, if it exists, defaulting to 2000.0 otherwise.

=cut

sub to_EQUINOX {
  my $self = shift;
  my $FITS_headers = shift;
  my $equinox = 2000.0;
  if ( exists $FITS_headers->{"CAT-EQUI"} ) {
    $equinox = $FITS_headers->{"CAT-EQUI"};