Data & attribution
Every map we render is built from open astronomical data. We're grateful to the people who maintain it.
- Star catalog
- HYG Database © David Nash / Astronomy Nexus, licensed CC BY-SA. We render stars to visual magnitude 6.5 — everything a perfect dark sky shows the naked eye.
- Constellation lines & Milky Way outlines
- From the data files of d3-celestial © Olaf Frohn (BSD-3-Clause); Milky Way outlines derived from Jose R. Vieira's outline catalog.
- Astronomy calculations
- Sidereal time via Astronomy Engine © Don Cross (MIT).
- Location search
- Geocoding by Nominatim, data © OpenStreetMap contributors (ODbL).
- Typefaces
- Cormorant Garamond and Inter, both under the SIL Open Font License.