# HYG 4.4 star-data derivative

HYG database by David Nash / Astronexus. [Source](https://codeberg.org/astronexus/hyg). Data license: [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/).

This data derivative retains CC BY-SA 4.0. The application code has its own separate license. The source digest, units and modifications are in manifest.json. The original compressed source is not redistributed here. No NASA planet, AT-HYG, private ledger, research corpus or credential is included.

Positions/directions are source epoch/equinox 2000.0, not a current ephemeris. Source uncertainties and per-field measurement flags are absent. Cartesian velocities are source-derived pc/year, not AT-HYG km/s; zero/missing inputs are not proof of a measured zero. Unknown-distance rows have no 3D position or Cartesian propagation. Sol is retained at the origin and excluded from background cells.