The ULySS package requires the GDL (free) or IDL (proprietary) compiler.
The sources, the models and some demonstration data can be downloaded as a single gzipped tar file containing routines, models and data:
ulyss.1.3.1.tar.gz. There is a unix configuration script and a makefile to test some dependencies and to set the paths to the sources. After unpacking the tar file, type in the main directory: make install. (the package was also reported to work under M-S windows, but is not routinely tested with this system).
The GDL/IDL file uly_startup.pro, automatically created when the package is installed, can conveniently be called from the personal GDL/IDL startup file.
This package is free software distributed under the terms of the GNU General Public License in the hope it will be useful. We would also be pleased to bring our expertise and collaborate to projects that would use the package.

Beside the official distribution of the package, you may wish to download other models or optional routines.

If ULySS was helpful to your research an acknowledgment would be appreciated:

• Cite the paper: Koleva, M., Prugniel, Ph., Bouchard, A. and Wu, Y., 2009, A&A 501, 1269 (arXiv:0903.2979). If you use the SSP models, you should cite also Koleva et al. 2008 MNRAS, 385, 1998, where a validation is presented.
• Indicate the URL of the ULySS home page as a footnote.

The following articles describe or validate the method or present applications:

• Prugniel, Ph., Vauglin, I., Koleva, M., 2011, The atmospheric parameters and spectral interpolator for the MILES stars, A&A, 531, A165
• Koleva, M., De Rijcke, S., Prugniel, Ph., Zeilinger, W. W., Michielsen, D., 2009, Formation and Evolution of Dwarf Elliptical Galaxies - II. Spatially resolved star-formation histories, MNRAS, 396, 2133
• Koleva, M., Gupta, R., Prugniel, Ph., Singh, H., 2008, Age, Metallicity and alpha-element Abundances in Stellar Populations, ASPCS, 390, 302
• Koleva, M., Prugniel, Ph., Ocvirk, P., Le Borgne, D., Soubiran, C., 2008, Spectroscopic ages and metallicities of stellar populations: validation of full spectrum fitting, MNRAS, 385, 1998
• Michielsen, D., Koleva, M., Prugniel, Ph., 2007, Toward a Solution for the Ca II Triplet Puzzle: Results from Dwarf Elliptical Galaxies, ApJ 670, L101
• Koleva, M., Prugniel, Ph., Ocvirk, P., Le Borgne, D., 2007, Age and metallicity of Galactic clusters from full spectrum fitting, IAUS 241, 185
• Koleva, M., Prugniel, Ph., Ocvirk, P., Le Borgne, D., Chilingarian, I., Soubiran, C., 2007, Comparison of different spectral population models, IAUS 241, 183
• Prugniel, Ph., Koleva, M., Ocvirk, P., Le Borgne, D., Soubiran, C., 2007, Analysis of stellar populations with large empirical libraries at high spectral resolution, IAUS 241, 68
• Koleva, M., Bavouzet, N., Chilingarian, I., Prugniel, P., 2007, Validation of Stellar Population and Kinematical Analysis of Galaxies, 2007spts.conf..153K

These other articles are also worth to mention since they describe similar approaches:

• Ocvirk, P., Pichon, C., Lancon, A., Thiebaut, E., 2006, STECKMAP: STEllar Content and Kinematics from high resolution galactic spectra via Maximum A Posteriori, MNRAS, 365, 74
• Ocvirk, P., Pichon, C., Lancon, A.; Thiebaut, E., 2006, STECMAP: STEllar Content from high-resolution galactic spectra via Maximum A Posteriori, MNRAS, 365, 46
• Chilingarian, Igor; Prugniel, Philippe; Sil'Chenko, Olga; Koleva, Mina, 2007, NBursts: Simultaneous Extraction of Internal Kinematics and Parametrized SFH from Integrated Light Spectra, IAUS, 241, 175
• M. Cappellari and E. Emsellem, Parametric Recovery of Line-of-Sight Velocity Distributions from Absorption-Line Spectra of Galaxies via Penalized Likelihood, PASP, 116, 138

ULySS uses functions from the Astronomy User's Library whose installation is a pre-requisite.

Other libraries are also used, and for convenience the sources are included in the directory dep:

• MPFIT, Craig Markwardt GDL/IDL implementation of the MINPACK-1 algorithm (by Moré et al., 1980, available in netlib). Levenberg-Marquart minimization [Note that ULySS has been tested with a 2008 version of this program, included in the 'dep/' directory].
• PRO2HTML, fr om Erin Sheldon, HTML rendering of a source program.
• Graphic programs from David Fanning.

The development of ULySS started from an adaptation of the ppxf program of M. Cappellari, and we kept from this program the principle of optimizing the linear parameters within the Levenberg-Marquart iteration (in the user's function), as well as the penalization for the Gauss-Hermite coefficients of the LOSVD.

Several students contributed to the development and tests of these programs. The authors of ULySS acknowledge in particular Nicolas Bavouzet, Paul Blondé, Igor Chilingarian and Martin France.
The development benefited also from many tutorials and programming tips published on the web. In particular the Coyote's Guide to IDL Programming by David Fanning is a real gold mine for the IDL developers.