Gyotoy(1) visualize one geodesic in Kerr metric


gyotoy [input.xml]


Gyoto is a framework for computing geodesics in curved space-times. The gyotoy utility program uses this framework to compute and display a single geodesic (the trajectory of a massive or mass-less particle) in Kerr metric.

gyotoy takes as optional argument a scenery description in XML format (input.xml). This scenery must contain a Astrobj section of kind Star. Alternatively, a default scenery is loaded.

The user can then interactively select initial parameters and redraw the geodesic as many time as needed. the Projection parameters allow rotating the view and various menu entries are rather self-explanatory. Entries in the File menu allow saving the display as an image file, saving the parameters as an XML description, or saving the geodesic's coordinates in an ASCII file.

gyotoy is only a small utility to visualise a single geodesic. It can also be invoked from the yorick(1) prompt for building more complex graphics and for scripting. Have a look at the gyoto.i and gyotoy.i files in yorick's Y_SITE directory.

A companion program, gyoto(1), can be used to compute an entire Gyoto scenery using relativistic ray-tracing.


The "Star" object in Gyoto is part of the standard plug-in. If the GYOTO_PLUGINS environment variable is set, it must contain at least "stdplug" for gyotoy to run properly.


Thibaut Paumard <[email protected]> wrote this manual.