Galactic Dynamics Tutorial data

Subsets of public survey catalogues prepared for the data chapters of the AGAMA-based tutorial https://github.com/vasilybelokurov/galactic-dynamics-tutorial (site: https://vasilybelokurov.github.io/galactic-dynamics-tutorial/). Every file is rebuilt by `scripts/build_data.py` in that repository, which contains the exact SQL and download URLs. The queries were run on WSDB (Cambridge), which uses the q3c sky indexing (Koposov & Bartunov 2006, https://ui.adsabs.harvard.edu/abs/2006ASPC..351..735K). The files contain raw observables and their uncertainties; no Galactocentric coordinates are provided, so that users choose (and can vary) the solar position and velocity themselves. Format: Apache Parquet (zstd compression). Read with `pandas.read_parquet(path)`. Units: angles deg; parallax mas; proper motions mas/yr (pmra includes cos dec); velocities km/s; magnitudes mag; distances and radii kpc. Missing values are NaN Full description of each file, its selection, columns, checksums and the sources to cite: see README.md in this record.