Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
Astro::Telescope(3)   User Contributed Perl Documentation  Astro::Telescope(3)

NAME
       Astro::Telescope	- class	for obtaining telescope	information

SYNOPSIS
	 use Astro::Telescope;

	 $tel =	new Astro::Telescope( 'UKIRT' );

	 $latitude = $tel->lat;
	 $longitude = $tel->long;
	 $altitude = $tel->alt;

	 %limits = $tel->limits;

	 @telescopes = Astro::Telescope->telNames();

DESCRIPTION
       A class for handling properties of individual telescopes	such as
       longitude, latitude, height and observational limits.

METHODS
   Constructor
       new Create a new	telescope object. Takes	the telescope abbreviation as
	   the single argument.

	     $tel = new	Astro::Telescope( 'VLA'	);

	   An argument must be supplied. Returns "undef" if the	telescope is
	   not recognized.

	   If more than	one argument is	supplied the assumption	is that	the
	   user	is supplying telescope details.	In that	case, "Name" and
	   "Long" must be supplied, and	either the geodetic latitude and
	   altitude ("Lat" and "Alt" --	but if "Alt" is	not supplied it	will
	   default to zero and this class will issue a warning), the
	   geocentric latitude and distance ("GeocLat" and "GeocDist"),	or the
	   parallax coefficients ("Parallax") must be supplied.	Latitudes and
	   longitudes must be given in radians,	altitude and distance in
	   metres, and the parallax constants in units of Earth	radii.

	     $tel = new	Astro::Telescope('telescope');
	     $tel = new	Astro::Telescope(Name => 'JCMT', Long => $long,	Lat => $lat );

   Accessor Methods
       name
	   Returns the abbreviated name	of the telescope. This is the same as
	   that	given to the constructor (although it will be upper-cased).

	   The object can be reconfigured to a new telescope by	supplying a
	   new abbreviation to this method.

	     $tel->name('JCMT');

	   The object will not change state if the name	is not known.

       fullname
	   Returns the full name of the	telescope. For example,	if the
	   abbreviated name is "JCMT" this will	return "JCMT 15	metre".

       obscode
	   Returns or sets the IAU observatory code as listed at
	   http://cfa-www.harvard.edu/iau/lists/ObsCodes.html. The object will
	   not change state if the observatory code is not known.

       long
	   Longitude of	the telescope (east +ve). By default this is in
	   radians.

	   An argument of "d" or "s" can be supplied to	retrieve the value in
	   decimal degrees or sexagesimal string format	respectively.

	    $string = $tel->long("s");

       lat Geodetic latitude of	the telescope. By default this is in radians.

	   An argument of "d" or "s" can be supplied to	retrieve the value in
	   decimal degrees or sexagesimal string format	respectively.

	     $deg = $tel->lat("d");

       alt Altitude of the telescope in	metres above mean sea level.

       parallax
	   Return the parallax constants, rho*sin(phi')	and rho*cos(phi'),
	   where rho is	the geocentric radius in Earth radii and phi' is the
	   geocentric latitude.	Returned as a hash where 'Par_C' is
	   rho*sin(phi') and 'Par_S' is	rho*cos(phi').

	     @parallax = $tel->parallax;

       geoc_lat
	   Return the geocentric latitude. By default this is in radians.

	   An argument of "d" or "s" can be supplied to	retrieve the value in
	   decimal degrees or sexagesimal string format	respectively.

	     $deg = $tel->geoc_lat("d");

       geoc_dist
	   Return the distance from the	centre of the Earth. By	default	this
	   is in metres.

	     $geoc_dist	= $tel->geoc_dist;

       obsgeo
	   Return the cartesian	coordinates of the observatory.	These are the
	   form	required for specifying	coordinates in the FITS	OBSGEO-X,
	   OBSGEO-Y and	OBSGEO-Z header	items.

	     ($x, $y, $z) = $tel->obsgeo;

	   Values are returned in metres.

       limits
	   Return the telescope	limits.

	     %limits = $tel->limits;

	   The limits are returned as a	hash with the following	keys:

	   type
	       Specifies the way in which the limits are specified.
	       Effectively the telescope mount.	Values of "AZEL" (for altaz
	       telescopes) and "HADEC" (for equatorial telescopes) are
	       currently supported.

	   el  Elevation limit of the telescope. Value is a hash with keys
	       "max" and "min".	Units are in radians. Only used	if "type" is
	       "AZEL".

	   ha  Hour angle limit	of the telescope. Value	is a hash with keys
	       "max" and "min".	Units are in radians. Only used	if "type" is
	       "HADEC".

	   dec Declination limit of the	telescope. Value is a hash with	keys
	       "max" and "min".	Units are in radians. Only used	if "type" is
	       "HADEC".

	   Only	some telescopes	have limits defined (please send patches with
	   new limits if you know them). If limits are not available for this
	   telescope limits corresponding to "above the	horizon" are returned.

	   If limits have been explicitly associated with this object using
	   the "setlimits" method then those limits will be returned.

       setlimits
	   This	method allows limits for this telescope	object to be set
	   explicitly.	The contents of	the limits hash	must be	those
	   described by	the "limits" method and	will be	returned by the
	   "limits" method). Limits set	in this	way will override built-in
	   limits.

	     $tel->setlimits( %limits );

	   Limits will be cleared if the object	is reconfigured	(eg by setting
	   the obscode).

   Class Methods
       telNames
	   Obtain a sorted list	of all supported telescope names.

	     @names = Astro::Telescope->telNames;

	   Currently only returns the PAL names, and only if Astro::PAL	is
	   available. If it is not available, return an	empty list.

REQUIREMENTS
       The list	of telescope properties	is currently obtained from those
       provided	by PAL ("Astro::PAL") and also from the	Minor Planet Center
       (http://www.cfa.harvard.edu/iau/lists/ObsCodes.html).

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

COPYRIGHT
       Copyright (C) 2007, 2008, 2010, 2012 Science and	Technology Facilities
       Council.	 Copyright (C) 1998-2005 Particle Physics and Astronomy
       Research	Council.  All Rights Reserved. This program is free software;
       you can redistribute it and/or modify it	under the same terms as	Perl
       itself.

perl v5.32.0			  2020-08-08		   Astro::Telescope(3)

NAME | SYNOPSIS | DESCRIPTION | METHODS | REQUIREMENTS | AUTHORS | COPYRIGHT

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=Astro::Telescope&sektion=3&manpath=FreeBSD+12.1-RELEASE+and+Ports>

home | help