# Data sources and licenses

SkySutra's catalog files are built by `tools/build_catalog.py` from open sources. Credit them
wherever the data is shown (the app's About page and the course's Part 2).

| File | Built from | License / terms |
| --- | --- | --- |
| `ss_stars.csv` (9,096 stars) | *The Bright Star Catalogue, 5th Revised Ed.*, Hoffleit & Warren (1991), Yale University Observatory; as JSON from [brettonw/YaleBrightStarCatalog](https://github.com/brettonw/YaleBrightStarCatalog) | Catalog distributed freely by NASA's Astronomical Data Center / CDS for research and education, with acknowledgement. Conversion code: MIT |
| proper names in `ss_stars.csv` | IAU Working Group on Star Names list (via the same repo) | Free to use with credit to the IAU |
| `ss_constellations.csv` (88) | [d3-celestial](https://github.com/ofrohn/d3-celestial) `constellations.json` | BSD 3-Clause, © 2015 Olaf Frohn |
| `ss_constellation_lines.csv` (743 segments) | d3-celestial `constellations.lines.json` (based on the IAU constellation charts), each vertex matched to the nearest catalog star (all within 0.3°) | BSD 3-Clause, © 2015 Olaf Frohn |
| constellation of each star | the catalog where it gives one; otherwise d3-celestial `constellations.bounds.json` (IAU boundaries, Davenhall & Leggett 1989); agrees with the catalog for 3,140 of 3,143 stars that have both | BSD 3-Clause |
| `ss_nakshatra_stars.csv` (27) | Junction stars (*yogatara*) as commonly listed; our own table | CC0 (ours) |
| Vedic names of stars and constellations | Common names (Dhruva = Polaris, Saptarishi = the Big Dipper, Agastya = Canopus, the 27 junction stars …); our own table | CC0 (ours) |

Coordinates are J2000. Proper motions are in milliarcseconds per year.