REFERENCE STAR CATALOG

Source: HYG Star Database 4.1, by David Nash / Astronomy Nexus and contributors.
https://github.com/astronexus/HYG-Database
Original source file:
https://github.com/astronexus/HYG-Database/blob/main/hyg/CURRENT/hygdata_v41.csv
Upstream licensing statement:
https://github.com/astronexus/HYG-Database/blob/main/hyg/CURRENT/LICENSE

License: Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0).
https://creativecommons.org/licenses/by-sa/4.0/
Legal code: https://creativecommons.org/licenses/by-sa/4.0/legalcode
The derived space/assets/stars.json catalog is distributed under the same license.
This data license does not replace licenses of Three.js, Astronomy Engine or the
application source code. No endorsement by the catalog authors is implied.

Changes: exclude the Sun, retain finite entries with visual magnitude <= 6.5,
retain J2000 right ascension (hours), declination (degrees), apparent visual
magnitude and B-V color index; round fields and sort by magnitude. No invented
stars or positional jitter is added. Generator: scripts/build-star-catalog.py.

Rendering: catalog J2000 directions are converted into the same fixed J2000
reference frame as the planetary display. B-V approximates blackbody color;
missing B-V uses neutral white. Magnitude-to-exposure and soft point sizes are
compressed display choices, not a calibrated observing instrument or stellar
radius measurement. Stars are a distant reference background; no dated proper
motion, annual parallax, atmospheric refraction/scintillation or local-horizon
occlusion is calculated. Do not use this background as a precision sky chart.