Treffer: Implementation of secular resonance support in the open-source python package "resonances".

This paper presents a major enhancement to the resonances Python package that now implements full support for identifying and analyzing secular resonances. Building upon the established mean-motion resonance framework, the implementation introduces: (1) a flexible mathematical expression parser supporting arbitrary combinations of fundamental frequencies (g , s , g i , s i), enabling analysis of both linear resonances (ν 5 , ν 6 , ν 16) and more than 70 nonlinear resonances from the literature; (2) specialized libration detection algorithms optimized for secular timescales, with automated parameter adaptation for extended integration times; (3) integration with existing mean-motion resonance workflows through consistent interfaces, allowing unified dynamical studies. The package has been tested through automated unit and integration tests and manual validation against examples from the literature, with all test cases—including ν 6 , ν 16 , z 1 , z 2 , 2 ν 6 − ν 5 , and 3 ν 6 − 2 ν 5 resonances passed successfully (with minor exceptions). The new version maintains the simplicity of the original interface, requiring only 3–4 lines of code for standard analyses, while providing researchers with powerful tools for systematic dynamical analysis and asteroid family studies. The package is available on GitHub under the MIT license. [ABSTRACT FROM AUTHOR]