Ruby/WCS

Ruby wrapper of WCSTools using SWIG. Provides calculation and conversion of sky positions in astronomical coordinates.

This is NOT WCSLIB wrapper.

Installation

Install WCSTools library. For RedHat Linux:
```
$ yum install wcstools-devel
```
Or download source code and install.

Install Ruby/WCS. Install from RubyGems as:

$ gem install wcs

Or install from source code:

$ ruby setup.rb

If WCSTools is installed at non-default directoriy:

$ ruby setup.rb all -- --with-wcs-dir=/usr/local/wcstools

$ gem install wcs -- --with-wcs-include=/usr/local/include \
  --with-wcs-lib=/usr/local/lib

Or add this line to your application's Gemfile:

gem 'wcs'

And then execute:

$ bundle

Usage

require 'wcs'

ra = 0
dec = 0
l,b = Wcs.wcscon(Wcs::J2000,Wcs::GALACTIC,0,0,ra,dec,2000)
#=> [96.33726964987589, -60.188551749437046]

naxis1  = 100       # Number of pixels along x-axis
naxis2  = 100       # Number of pixels along y-axis
ctype1  = "RA--TAN" # FITS WCS projection for axis 1
ctype2  = "DEC-TAN" # FITS WCS projection for axis 2
crpix1  = 0         # Reference pixel coordinates
crpix2  = 0         # Reference pixel coordinates
crval1  = 0         # Coordinate at reference pixel in degrees
crval2  = 0         # Coordinate at reference pixel in degrees
cd      = nil       # Rotation matrix, used if not NULL
cdelt1  = 0.1       # scale in degrees/pixel, if cd is NULL
cdelt2  = 0.1       # scale in degrees/pixel, if cd is NULL
crota   = 0         # Rotation angle in degrees, if cd is NULL
equinox = 2000      # Equinox of coordinates, 1950 and 2000 supported
epoch   = 2000      # Epoch of coordinates, for FK4/FK5 conversion

wcs = Wcs::WorldCoor.new(naxis1,naxis2,ctype1,ctype2,
  crpix1,crpix2,crval1,crval2,cd,cdelt1,cdelt2,
  crota,equinox,epoch)

xpix,ypix,offscl = wcs.wcs2pix(0.5,0.5)
#=> [5.000126927791313, 5.000317324553201, 0]

xpos,ypos = wcs.pix2wcs(12,34)
#=> [1.1998245865308625, 3.395274673610471]

Platforms tested

ruby 2.0.0p0 (2013-02-24 revision 39474) [x86_64-linux]

Copying License

This program is free software. You can distribute/modify this program under the same terms as LGPL. See "COPYING" file. NO WARRANTY.

Author

Masahiro TANAKA