First Section nutabl. Nutation is a small wobble of the Earth's rotational axis with an amplitude of about 9 arcsec and period of up to 18.6 years.
Current models represent the nutation quantities with well-defined series.
For efficiency, arc reads a previously generated nutation table for these values. Currently, the nutabl. The format of this file should be considered fixed. The first line of the header is purely descriptive and is ignored. In the current version of arc , only the start and stop time are read and used.