This is the gem library which calculates ephemeris datas by JPL(NASA Jet Propulsion Laboratory) method.
This library calculates rectangular coordinates and velocities of a target astronomical body which made an astronomical body the center on a Julian Day.(Coordinate system is ICRS)
Please refer the following link.
Please refer the following links about DE datas.
- HORIZONS System
To understand this library's in-depth specification, you need to comprehend contents of the following link well.
Supported DE Ver.
This library supports only DE430, now.
Settable astronomical bodies as target and center numbers.
- Solar system Barycenter
- Earth-Moon barycenter
- Earth Nutations
- Lunar mantle Librations
Add this line to your application's Gemfile:
And then execute:
Or install it yourself as:
$ gem install eph_jpl
obj = EphJpl.new("/path/to/JPLEPH", 11, 3, 2457465.5) p obj.target #=> Target atronomical body No. (Integer) p obj.target_name #=> Target atronomical body name (String) p obj.center #=> Center atronomical body No. (Integer) p obj.center_name #=> Center atronomical body name (String) p obj.jd #=> Julian Day (Float) p obj.km #=> KM flag (true: km unit, false: AU unit) (Boolean) p obj.unit #=> UNIT of positions and velocities (String) p obj.bin #=> Acquired data from binary file (Hash) p obj.calc #=> [x, y, z-position, x, y, z-velocity]
About binary file.
- Please get the binary file for DE430 from [ftp://ssd.jpl.nasa.gov/pub/eph/planets/Linux/de430/linux_p1550p2650.430].
- Please put "linux_p1550p2650.430" into a proper directory.
- Please rename as needed.
About arguments for target and center astronomical bodies.
- You can set a integer betweetn 1 and 15 as a target astronomical body.
- You can set a integer betweetn 0 and 13 as a center astronomical body.
- If a target astronomical body number < 14 and KM flag = false, units of position and velocity are au, au/day.
- If a target astronomical body number < 14 and KM flag = true, units of position and velocity are km, km/sec.
- If a target astronomical body number = 14 or 15, units of position and velocity are rad, rad/day.
After checking out the repo, run
bin/setup to install dependencies. Then, run
rake spec to run the tests. You can also run
bin/console for an interactive prompt that will allow you to experiment. Run
bundle exec eph_jpl to use the gem in this directory, ignoring other installed copies of this gem.
To install this gem onto your local machine, run
bundle exec rake install. To release a new version, update the version number in
version.rb, and then run
bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the
.gem file to rubygems.org.
Bug reports and pull requests are welcome on GitHub at https://github.com/komasaru/eph_jpl.
The gem is available as open source under the terms of the MIT License.