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Astro-FITS-HdrTrans-0.04
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/ Astro::FITS::HdrTrans::ACSIS

NAME

Astro::FITS::HdrTrans::ACSIS - class for translation of JCMT ACSIS headers

SYNOPSIS

  use Astro::FITS::HdrTrans::ACSIS;

DESCRIPTION

This class provides a set of translations for ACSIS at JCMT.

METHODS

can_translate

Returns true if the supplied headers can be handled by this class.

  $cando = $class->can_translate( \%hdrs );

For this class, the method will return true if the BACKEND header exists and matches 'ACSIS'.

COMPLEX CONVERSIONS

These methods are more complicated than a simple mapping. We have to provide both from- and to-FITS conversions All these routines are methods and the to_ routines all take a reference to a hash and return the translated value (a many-to-one mapping) The from_ methods take a reference to a generic hash and return a translated hash (sometimes these are many-to-many)

to_EXPOSURE_TIME

Uses the to_UTSTART and to_UTEND functions to calculate the exposure time. Returns the exposure time as a scalar, not as a Time::Seconds object.

to_OBSERVATION_MODE

Concatenates the SAM_MODE, SW_MODE, and OBS_TYPE header keywords into the OBSERVATION_MODE generic header, with spaces removed and joined with underscores. For example, if SAM_MODE is 'jiggle ', SW_MODE is 'chop ', and OBS_TYPE is 'science ', then the OBSERVATION_MODE generic header will be 'jiggle_chop_science'.

to_SYSTEM_VELOCITY

Converts the DOPPLER and SPECSYS headers into one combined SYSTEM_VELOCITY header. The first three characters of each specific header are used and concatenated. For example, if DOPPLER is 'radio' and SPECSYS is 'LSR', then the resulting SYSTEM_VELOCITY generic header will be 'RADLSR'. The results are always returned in capital letters.

to_VELOCITY

Converts the ZSOURCE header into an appropriate system velocity, depending on the value of the DOPPLER header. If the DOPPLER header is 'redshift', then the VELOCITY generic header will be returned as a redshift. If the DOPPLER header is 'optical', then the VELOCITY generic header will be returned as an optical velocity. If the DOPPLER header is 'radio', then the VELOCITY generic header will be returned as a radio velocity. Note that calculating the radio velocity from the zeropoint (which is the ZSOURCE header) gives accurates results only if the radio velocity is a small fraction (~0.01) of the speed of light.

REVISION

 $Id: ACSIS.pm,v 0.6 2006/02/07 03:02:44 bradc Exp $

SEE ALSO

Astro::FITS::HdrTrans, Astro::FITS::HdrTrans::Base

AUTHORS

Tim Jenness <t.jenness@jach.hawaii.edu>, Brad Cavanagh <b.cavanagh@jach.hawaii.edu>.

COPYRIGHT

Copyright (C) 2005-2006 Particle Physics and Astronomy Research Council. All Rights Reserved.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place,Suite 330, Boston, MA 02111-1307, USA