ORBITAL SKY — PHOTOMETRIC STARS AND GALACTIC LIGHT

Bright and faint stellar points: HYG Stellar Database version 4.1,
David Nash / Astronomy Nexus (Astronexus) and contributors.
https://github.com/astronexus/HYG-Database
https://codeberg.org/astronexus/hyg
Data source: Hipparcos, Yale Bright Star and Gliese catalogues.

Local adaptation: 25,791 entries up to apparent visual magnitude 7.5,
excluding the Sun. Positions, apparent magnitudes and B-V colour indices are
retained. 83 missing B-V values use an explicitly documented fallback of 0.65.
Source epoch: J2000.0, not a live view or current stellar variability model.
The subset and its source data are licensed CC BY-SA 4.0:
https://creativecommons.org/licenses/by-sa/4.0/
Full local licence and attribution: sky-photometric-license.txt
Pinned source, transformations, hashes and reference stars:
sky-photometric-sources.json
Reproduce with python scripts/prepare-star-catalogue.py (Python stdlib).

Unresolved galactic light: NASA Goddard Space Flight Center,
Scientific Visualization Studio. Visualization: Ernie Wright (USRA).
Gaia DR2 data: ESA / Gaia / DPAC.
https://svs.gsfc.nasa.gov/4851/
Original: milkyway_2020_4k.exr, without the Hipparcos/Tycho foreground.
Local sky-milkyway.jpg is 2048 x 1024, reduced in linear light from the source,
with a darker diffuse floor and neutral colour grade. No invented nebulae.
Map centre: RA 0 degrees. RA increases left; north is up.
Source, transformations and hash: sky-sources.json
Reproduce with python scripts/prepare-orbital-sky.py
Authoring dependencies: numpy, Pillow and OpenEXR.
https://www.nasa.gov/nasa-brand-center/images-and-media/
No NASA affiliation or endorsement is implied.

The renderer uses real apparent magnitudes with a fixed artistic exposure,
a restrained B-V palette, pixel-integrated compact cores and angular optical
wings. Bright stars have a small optional artistic glimmer; this is not
atmospheric scintillation in space. Reduced motion disables it.
The same celestial frame is used by both eyes. Stars are at optical infinity,
not placed at arbitrary nearby distances to introduce fake parallax.

Rendering references (ideas, no copied Stellarium implementation):
https://stellarium.org/doc/head/classStelSkyDrawer.html
https://diglib.eg.org/items/fc13d662-0f6a-4a23-9ae2-d7f1ec1afc78
https://cseweb.ucsd.edu/~henrik/papers/nightsky/

All runtime sky data is hosted locally. No external astronomy service is needed.