NAME
Astro::PAL  Perl interface to Starlink PAL positional astronomy library
SYNOPSIS
use PAL;
use PAL qw(:constants :pal);
($ra2000, $dec2000) = palFk45z($ra, $dec, 1950.0);
($mjd, $status) = palCldj($yy, $mn, $dd);
($lst, $mjd) = lstnow($long);
($lst, $mjd) = ut2lst_tel($yy,$mn,$dd,$hh,$mm,$ss,'JCMT');
DESCRIPTION
This modules provides a Perl interface to either the Starlink PAL positional astronomy library.
Return values are returned on the stack rather than being modified in place.
In addition small utility subroutines are provided that do useful tasks (from the author's point of view)  specifically routines for calculating the Local Sidereal Time.
Routines
There are 3 distinct groups of routines that can be imported into the namespace via tags:
 pal  import just the PAL routines
 constants  import the PAL constants
 funcs  import the extra routines
Each group will be discussed in turn.
PAL
The PAL routines directly match the C API with the caveat that returned values are returned on the perl argument stack rather than being modified directly in the call arguments. Arguments are never modified. This differs from the Astro::SLA wrapper around the SLALIB library.
For example,
($xi, $eta, $j) = palDst2p( $ra, $dec, $raz, $decz );
@pv = palDmoon( $date );
($nstrt, $fd, $j) = palDafin( $time, $nstrt );
If a routine returns an array as well as a status the status value is returned first:
($j, @iymsf) = palDjcal( $ndp, $djm );
If a routine returns multiple arrays they are returned as references:
($dvb, $dpb, $dvh, $dph) = palEvp( $date, $deqx );
@dvbarr = @$dvb;
Routines that take vectors or matrices should be given references to arrays:
@rmatn = palNut( $djtt );
@mposr = palDmxv( \@rmatn, \@mpos );
See the PAL or SLALIB documentation for details of the functions themselves.
Anomalies
 palObs

palObs is special in that it returns an empty list if the return status is bad. Additionally, palObs is called with a single argument and the behaviour depends on whether the argument looks like an integer or a string.
($ident, $name, $w, $p, $h) = palObs( 27 ); ($ident, $name, $w, $p, $h) = palObs( "JCMT" );
 palAopqk

palAopqk can be called either with a reference to an array or a list
@results = palAopqk( $rap, $dap, @aoprms ); @results = palAopqk( $rap, $dap, \@aoprms );
 palAoppat

For the C API the calling convention is to modify the AOPRMS array in place, for the perl API we accept the AOPRMS array but return the updated version.
@aoprms = Astro::PAL::palAoppat( $date, \@aoprms ); @aoprms = Astro::PAL::palAoppat( $date, @aoprms );
Constants
Constants supplied by this module (note that they are implemented via the constant pragma):
 DPI  Pi
 D2PI  2 * Pi
 D1B2PI  1 / (2 * Pi)
 D4PI  4 * Pi
 D1B4PI  1 / (4 * Pi)
 DPISQ  Pi ** 2 (Pi squared)
 DSQRPI  sqrt(Pi)
 DPIBY2  Pi / 2: 90 degrees in radians
 DD2R  Pi / 180: degrees to radians
 DR2D  180/Pi: radians to degrees
 DAS2R  pi/(180*3600): arcseconds to radians
 DR2AS  180*3600/pi: radians to arcseconds
 DH2R  pi/12: hours to radians
 DR2H  12/pi: radians to hours
 DS2R  pi / (12*3600): seconds of time to radians
 DR2S  12*3600/pi: radians to seconds of time
 D15B2P  15/(2*pi): hours to degrees * radians to turns
Extra functions
These are exportable using the 'funcs' tag or used directly through the Astro::PAL namespace.
They directly match the Astro::SLA equivalents.
 lstnow_tel

Return current LST (in radians) and MJD for a given telescope. The telescope identifiers should match those present in palObs. The supplied telescope name is converted to upper case.
($lst, $mjd) = lstnow_tel($tel);
Aborts if telescope name is unknown.
 lstnow

Return current LST (in radians) and MJD (days) Longitude should be negative if degrees west and in radians.
($lst, $mjd) = lstnow($long);
 ut2lst

Given the UT time, calculate the Modified Julian date (UTC) and the local sidereal time (radians) for the specified longitude.
($lst, $mjd) = ut2lst(yy, mn, dd, hh, mm, ss, long)
Longitude should be negative if degrees west and in radians.
 ut2lst_tel

Given the UT time, calculate the Modified Julian date and the local sidereal time (radians) for the specified telescope.
($lst, $mjd) = ut2lst_tel(yy, mn, dd, hh, mm, ss, tel)
AUTHOR
Tim Jenness >tjenness@cpan.org<
REQUIREMENTS
The PAL library is available from Starlink.
COPYRIGHT
Copyright (C) 2014 Tim Jenness Copyright (C) 2012 Tim Jenness and the Science and Technology Facilities Council.
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 3 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 021111307, USA