Star positions and photometry: HYG Stellar Database v4.1, David Nash / Astronomy Nexus.
https://github.com/astronexus/HYG-Database/tree/main/hyg/CURRENT
https://www.astronexus.com/hyg

HYG and this adapted catalogue are licensed CC BY-SA 4.0:
https://creativecommons.org/licenses/by-sa/4.0/

Changes: Sun excluded; stars filtered to apparent visual magnitude <= 8;
right ascension, declination, visual magnitude, B-V colour, RA and declination
proper motions packed as little-endian float32 records in hyg-v41.bin.
Positions retain HYG's J2000 epoch/equinox. Proper motion and precession are
applied for the current date by the renderer. Artistic scintillation, bloom
and exposure do not represent measured stellar variability.

Timezone fallback coordinates: IANA tz database zone.tab, public domain.
IP approximation: https://ipapi.co/latlong/ (once per session / six hours).
Only rounded coordinates are retained in this browser's session storage.
No GPS, device orientation, or browser location permission is requested.
IP/VPN location and timezone fallback are estimates, not a precise position.

Astronomy references:
https://aa.usno.navy.mil/faq/GAST
https://aa.usno.navy.mil/faq/alt_az
IAU 1976 precession (Lieske et al.), J2000 to observation date.

The landscape faces west. Stars below the horizon are not shown in the sky.
Moon position, phase and bright-limb tilt use SunCalc 2.0.1 (BSD-2-Clause),
with topocentric parallax and refraction, at the same observer location and
scrubbed instant as the stars. https://github.com/mourner/suncalc
The apparent lunar size/glow and the sun/day-night lighting remain artistic.