# Star data credits

Star positions, visual magnitudes and B-V color indices are from the
[HYG Database v4.1](https://github.com/astronexus/HYG-Database), compiled by
David Nash / Astronexus from the Hipparcos, Yale Bright Star and Gliese catalogs.

The catalog and this adapted subset are licensed under
[Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/).

Changes: excluded the Sun, selected stars with visual magnitude 7 or brighter,
converted J2000 equatorial coordinates into unit view directions, retained
the forward hemisphere, rounded coordinates, and exported the result as JSON.
The fixed view is centered on right ascension 4 hours, declination +15 degrees.
No star positions are randomized. Display brightness is compressed and colors
are subtly approximated from B-V for readability on a screen.

This is an illustrative background, not the Moon's current position in the sky
or a simulation of photographic exposure.

Data file in this project: `app/data/stars.json`.
Rebuild with `python scripts/build-star-catalog.py path/to/hygdata_v41.csv`.

Original CSV:
https://raw.githubusercontent.com/astronexus/HYG-Database/main/hyg/CURRENT/hygdata_v41.csv