Gyoto aims at providing a framework for computing orbits and ray-traced images in General relativity. It consists in a library (libgyoto), utility programs, and a plug-in for the Yorick programing language.

We request that use of Gyoto in scientific publications be properly acknowledged. Please cite:

GYOTO: a new general relativistic ray-tracing code, F. H. Vincent,
T. Paumard, E. Gourgoulhon & G. Perrin, Classical and Quantum
Gravity 28, 225011 (2011) [arXiv:1109.4769]

We also request that Gyoto modifications, extensions or plug-ins leading to a scientific publication be made public as free software reasonably fast (within one year after publication of the scientific paper), for instance by contributing it directly to the Gyoto code base. Contributors will be listed in the relevant source files as well as in the AUTHORS file in the package.

Gyoto is Copyright 2011-2019 Thibaut Paumard, Frédéric Vincent, Odele Straub and Frédéric Lamy (To ease reading on non-UTF8 systems, French accents are omitted in file headers).

Gyoto 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.

Gyoto 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 Gyoto. If not, see http://www.gnu.org/licenses/.

File python/doxyfile.py is Copyright 2008 Prabhu Ramachandran under BSD style license. File python/numpy.i is Copyright (c) 2005-2015, NumPy Developers under BSD 3-clause license. File bin/optionparser.h is Copyright (C) 2012 Matthias S. Benkmann. See each file for details.

Refer to the file INSTALL.Gyoto.md for building and installing Gyoto.

Several sample files are provided in doc/examples. You can ray-trace those sceneries with:

gyoto <input-file.xml> <output-file.fits>

FITS files can be read by a variety of free and proprietary software. See http://heasarc.gsfc.nasa.gov/docs/heasarc/fits.html.

Custom metrics and astronomical objects can be added fairly easily by implementing them as a Gyoto plug-in. This, of course, requires knowledge of the C++ language. The user manual contains detailed instructions. -- Thibaut Paumard, Thu, 10 Jan 2019.