Credits & data sources

WatchSat is built entirely on public orbital data, real NASA/ESA/USGS imagery, and open-source software. Full credit to the people and institutions who made it possible.

Orbital data

Satellite orbital elements (TLEs) come from CelesTrak, maintained by Dr. T. S. Kelso at the Center for Space Standards & Innovation, which redistributes the US Space Force’s tracking catalog. WatchSat’s /api/tle proxy identifies itself to CelesTrak by user agent and caches responses at the edge for about 30 minutes — see Data & methodology for the full pipeline.

Launch schedule

Upcoming launch countdowns on the launches page come from The Space Devs’ Launch Library 2 (CC BY 4.0) — mission, provider, rocket, pad, timing, and webcast links, proxied and trimmed server-side before they reach the browser.

Space weather

The aurora forecast on the aurora page uses the planetary Kp index and 3-day geomagnetic forecast from NOAA’s Space Weather Prediction Center (public domain), proxied and trimmed server-side before it reaches the browser. The live globe’s aurora-oval layer draws SWPC’s 30-minute OVATION aurora forecast, through an edge-cached proxy.

People in space

The crew roster on the humans in space page comes from The Space Devs’ Launch Library 2 (CC BY 4.0) and is refreshed every six hours by WatchSat’s scheduled job.

Spacecraft positions

Positions, speeds and trajectories of Voyager 1 and 2, the Pioneers, New Horizons and the active deep-space fleet on the deep space and solar system pages are state vectors from NASA/JPL Horizons, JPL’s solar-system ephemeris service.

Earth imagery

The day and night Earth textures are NASA’s Blue Marble: Next Generation (day) and Black Marble 2016 (night lights), both from NASA Earth Observatory; cloud cover uses NASA’s Blue Marble cloud mosaic. Live ground-imagery refreshes in sky mode draw on NASA GIBS (Global Imagery Browse Services), part of NASA EOSDIS. The landing page opens on a NASA astronaut photograph of Italy and the Alps at night from the International Space Station (Expedition 46, via NASA Johnson’s Gateway to Astronaut Photography of Earth), followed by NASA’s Blue Marble (2002) Eastern Hemisphere composite (both public domain).

Sky-mode ground tiles

When Explore Sky or Live Sky AR runs at the High or Balanced quality preset, close-up ground tiles come from Esri World Imagery — required credit: “Esri, Maxar, Earthstar Geographics, and the GIS User Community.” The Battery preset, and any Esri failure, falls back to NASA GIBS instead.

Sun

The Sun’s photosphere and corona come from NASA’s Solar Dynamics Observatory (SDO) — HMI continuum imagery for the visible disk, and AIA 171 Å imagery (remapped from false colour toward visible tones) for the corona.

Moon

Moon colour and relief textures come from NASA’s Lunar Reconnaissance Orbiter — the LROC WAC natural-colour mosaic and LOLA elevation data — via the NASA Scientific Visualization Studio’s CGI Moon Kit.

Planets

Mars and Venus use the USGS Astrogeology Science Center’s primary global mosaics (NASA/JPL/USGS, public domain) — the Viking Orbiter global colour mosaic for Mars, and the Magellan C3-MDIR synthetic-colour radar mosaic for Venus. Jupiter uses NASA/JPL/Space Science Institute’s Cassini cylindrical global map (PIA07782, public domain), and Pluto uses NASA/JHUAPL/SwRI’s New Horizons global colour mosaic (PIA11707, public domain). Mercury and Saturn (with its rings) use community-redistributed equirectangular basemaps with heritage from NASA’s MESSENGER and Cassini missions respectively — full file-by-file sourcing is in the attribution register linked below.

Planet and moon facts

The details cards on the solar system page take their physical and orbital figures from NASA’s NSSDCA planetary fact sheets and JPL Solar System Dynamics’ planetary satellite tables, and moon counts from NASA Science. Every card links the exact pages its numbers came from.

Solar-system photographs

The photographs in those cards — every planet, the major moons, the spacecraft and the Voyagers’ own pictures — are NASA’s: frames from its missions and telescopes (Voyager, Galileo, Cassini, MESSENGER, New Horizons, Apollo, SDO and others) and photos of the spacecraft themselves, from NASA Science (including the NASA/JPL Photojournal), NASA’s Image and Video Library and nasa.gov. Each card credits its image and links to its source page; where NASA describes a frame as false or enhanced colour or black and white, or it is an artist’s concept (Pioneer 11, Parker Solar Probe), the caption says so.

Blog photographs

The photographs on the blog are real ones, not WatchSat renders: NASA’s (public domain), from its Image and Video Library, the NASA/JPL Photojournal, nasa.gov and the Scientific Visualization Studio, and NOIRLab’s (CTIO/NOIRLab/NSF/AURA, KPNO/NOIRLab/NSF/AURA and International Gemini Observatory/NOIRLab/NSF/AURA, CC BY 4.0). Each post’s caption credits its image, links to its source page and names its license, and says when a CC BY picture was cropped.

Star background

The all-sky Milky Way backdrop is NASA’s Scientific Visualization Studio “Deep Star Maps 2020” (SVS 4851), a public-domain equirectangular star map.

Bright stars

Individual stars rendered in the sky view come from the ESA Hipparcos Catalogue (~79,000 real stars to magnitude 9, CDS I/239), falling back to the Yale Bright Star Catalog (BSC5; Hoffleit & Warren, Yale University Observatory, via a MIT-licensed JSON packaging by Bretton Wade) if that fetch ever fails.

Weather & geocoding

Simulated-sky weather, the aurora page’s cloud forecast and city-name location search are powered by Open-Meteo, a free, keyless weather and geocoding API.

Open source

WatchSat is built with Three.js (WebGL rendering), satellite.js (SGP4/SDP4 propagation), Astronomy Engine (ephemerides), and React with React Router — all open-source and MIT-licensed.

This page summarizes the credits; for the complete, file-by-file, machine-readable list see the full attribution register.

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