Credits & licenses

AstroSky is an independent project by standon99, built with open-source software and the work of the data producers below.

Maps and terrain

Basemap from OpenFreeMap, © OpenMapTiles, data © OpenStreetMap contributors under ODbL 1.0. The Dark style is adjusted for dimmer roads and waterways and stronger shorelines. Original style and font-source notices.

Terrain from Mapterhorn and its data contributors. Its terrain sources carry individual open-data licenses. See the complete producer and license list, including the Copernicus GLO-30 global base and regional elevation producers.

Sky brightness

David Lorenz’s 2025 Light Pollution Atlas models artificial brightness at zenith using annual nighttime lights processed by the Earth Observation Group at the Colorado School of Mines from NOAA VIIRS observations. The app preserves the atlas’s native colors and zones; filtering changes transparency. Directional sampling is an application-derived regional estimate.

These are modeled overhead brightness values, separate from visually observed Bortle classes. Atlas zones and brightness units · Bortle distinction.

No explicit reuse license was found in the published atlas material reviewed. The atlas is not covered by this application's MIT license; this credit does not claim otherwise. Provider review.

Elevation and places

Elevation: Open-Meteo, service data under CC BY 4.0, using Copernicus DEM GLO-90 from the Copernicus program. The free API has noncommercial-use and request-limit terms.

Place search: Photon, hosted by komoot, using © OpenStreetMap contributors. The public service permits reasonable use and may throttle heavy traffic.

Celestial objects and calculations

Object data adapted from OpenNGC, Mattia Verga and contributors, under CC BY-SA 4.0. Adaptations by standon99, 2026: selected fields, decimal J2000 coordinates, normalized identifiers, familiar aliases, and planetary search entries. The adapted catalog and featured subset retain CC BY-SA 4.0.

• Catalog notice and complete catalog license
• Original source acknowledgments, including NED, HyperLEDA, SIMBAD, HEASARC, and Harold Corwin; contributors

Positions and observing calculations use Astronomy Engine, Don Cross, MIT. Timezone lookup uses tz-lookup. Rise/set assumes a flat, unobstructed horizon; the displayed terrain does not change that assumption.

Software, icons, and fonts

Full dependency copyright and license notices, including React, MapLibre, Astronomy Engine, Base UI, Recharts, pako, and their frontend dependencies. Copied UI components are adapted from shadcn/ui, MIT. Lucide icons retain ISC notices and MIT notices for Feather-derived icons by Cole Bemis.

Geist and Geist Mono: The Geist Project Authors and Vercel / basement.studio, under SIL Open Font License 1.1.