Data sources and licence

Orbital elements: Space-Track

The orbital elements of every satellite come from Space-Track, the public catalogue of the US Space Force, refreshed every four hours. The elements remain Space-Track's data. Orbinauts passes them on, and everything it computes from them, under the United States Space Command's blanket approval for the redistribution of basic space situational awareness data, which is conditioned on appropriate citation. The credit line below is that citation, and it travels with every answer.

ISS ephemeris: NASA

The ISS ephemeris is published by NASA, produced by the flight controllers at the Johnson Space Center. It is a work of the United States Government and in the public domain. NASA is acknowledged as its source; nothing here is endorsed by NASA. It is the only ephemeris Orbinauts holds: no operator publishes one for the other satellites, so every answer about them is computed from the orbital elements above, and each satellite page says so.

Constellation membership: CelesTrak and the operators

Which satellites make up each constellation is not in the orbital elements: a satellite belongs to a constellation because its operator says so, and the set changes as one is launched or retired. The operator's own status table decides who is in — the US Coast Guard Navigation Center's operational advisory for GPS; the European GNSS Service Centre's table for Galileo, whose satellites marked not usable are left out; the GLONASS constellation status of Russia's Information and Analysis Center for Positioning, Navigation and Timing, whose satellites in operation are the ones kept; and, for BeiDou, the satellites in use in all three of its orbits in the table of the China Satellite Navigation Office's test and assessment centre — and that constellation's group at CelesTrak gives each of them the catalogue number the orbital elements are fetched by. BeiDou's operator draws its table with a script that nothing but the page itself can read, so the table is read where the Information and Analysis Center republishes it, in Russian and saying whose data it is; when the two were compared they listed the same satellites. BlueBird has neither source: its operator, AST SpaceMobile, publishes its launches but no status table, and CelesTrak keeps no group for it. Its satellites are the ones Space-Track's catalogue lists on orbit under the name it gives them, SPACEMOBILE-001 and on, checked against a table of every launch AST SpaceMobile has announced, kept by hand, in which BlueBird 7, left in too low an orbit by its launcher in April 2026, is marked lost. Where the two sources cannot be reconciled the list is left as it was and the difference is reported, so a stale group cannot quietly become the site's answer. The lists in use, as this site was last built:

• GPS: 32 satellites, from its status table, numbered through CelesTrak's group, with what each one is read from its operator's constellation table, last agreed Sep 16, 2026.
• Galileo: 27 satellites, from its status table, numbered through CelesTrak's group, last agreed Sep 9, 2026.
• BeiDou: 37 satellites, from its status table, numbered through CelesTrak's group, last agreed Sep 15, 2026.
• GLONASS: 22 satellites, from its status table, numbered through CelesTrak's group, last agreed Sep 15, 2026.
• BlueBird: 12 satellites, from the launches its operator has announced, numbered through Space-Track's catalogue, searched by name, last agreed Sep 15, 2026.

The site writes nothing by hand about any one satellite of a constellation: each one's page names it as the catalogue does and says what its orbital elements and its constellation's list say, each is on the live map like any other satellite, and its constellation's page lists it, links its page and says how many are above your horizon right now. A satellite of a constellation has a brightness only where Heavens-Above, below, has published its standard magnitude, entered by catalogue number in a table kept beside its constellation's membership; none has one yet, so none is ever named as visible.

Standard magnitudes: Heavens-Above

How bright a pass will look is predicted, never measured, and every prediction starts from one number per satellite: its standard magnitude, how bright it would look from 1,000 km away with half its lit side turned towards you. No catalogue publishes these as data, so each is entered by hand from the satellite's page at Heavens-Above, which states them on the convention the brightness model is normalised to: 1,000 km range, 50% illuminated, average brightness. The values in use, for each satellite the site writes about:

A satellite counts as naked-eye when the model, at the low end of the altitude it keeps, straight overhead and with half its lit side turned towards you, predicts magnitude 4.0 or brighter — the faintest a pass may be and still count as visible. Only naked-eye satellites get pass times for a city; every other satellite Orbinauts tracks keeps its place on the live map and its own page. Where the field publishes no standard magnitude, none is estimated here, so the satellite is never naked-eye.

Heavens-Above is Chris Peat's site, running since 1998; the values are quoted, not republished as a dataset. What Orbinauts computes from them — the predicted brightness of a pass — is its own, under the licence below. The how it works page explains what the model does with the number and what it ignores.

Satellite facts: the operators

What a satellite's page says of it by hand — when it was launched and when it ended, what it watches or sees or carries or was first at, who flies it, how much it weighs and how big it is, how long it was built to last, and the day it took over from another — is read on its operator's or its historians' own pages, and a fact no such page states is left out rather than guessed. The pages the facts were read on:

• The satellites the site wrote about first:
  • Chandra: the Chandra X-ray Center's specifications and page about the observatory.
  • Terra: NASA's About Terra page, and the MODIS page for its full picture of the Earth.
  • Landsat 9: NASA's mission page and the USGS's Landsat 9 page; its mass is Wikipedia's, since neither states one.
  • GOES-19: NOAA's announcement of GOES-19 as GOES East, its page of the GOES-R spacecraft for its mass, and the imager page for its full picture of the Earth.
  • Meteosat-12: EUMETSAT's announcement of the day it took over from Meteosat-10, and ESA's Meteosat Third Generation facts and figures for its mass.
  • Hispasat 30W-6: Hispasat's launch-day release and fleet page; its mass is Gunter's Space Page's, since Hispasat states none.
  • Vanguard 1: NASA's page on its launch, the Smithsonian's flight backup for its size and mass, and NASA's archive of spacecraft, the NSSDCA, for the year it fell silent.
• The Copernicus Sentinels:ESA's facts and figures for Sentinel-1, Sentinel-2, Sentinel-3, Sentinel-5P and Sentinel-6, and its word on the end of Sentinel-1A; the Copernicus SentiWiki and Sentinel Online, where ESA dates Sentinel-2C's taking over from Sentinel-2A and Sentinel-2A's extended campaign; ESA's operations page for Sentinel-5P, which it flies; and EUMETSAT's pages on Sentinel-3, Sentinel-6 and Sentinel-6B, which it flies.
• The weather programmes, from EUMETSAT and NOAA:
  • MetOp-SG A1: EUMETSAT's launch announcement, its Metop series page and the news of its first and second instruments entering service, its Metop-SG instruments page for its mass, and ESA's MetOp-SG facts and figures for its coverage.
  • Metop-B and Metop-C: EUMETSAT's Metop page and Metop series page, its annual report for 2025 for their roles and its annual report for 2013 for Metop-B's handover, and ESA's MetOp facts and figures for their mass.
  • Meteosat-11: EUMETSAT's Meteosat series page, its MSG services page and notice of Meteosat-12 becoming the primary satellite for its role, the announcement of the day Meteosat-12 took over from Meteosat-10, its Meteosat Second Generation page for its full picture of the Earth, and ESA's introduction to MSG for its mass.
  • GOES-16, GOES-17 and GOES-18: NOAA's page on the GOES-R series' transition to operations for their launches and handovers, with its announcements of GOES-17 and GOES-18 as GOES West; its list of the geostationary satellites flying and the GOES status page of its satellite operations for the two kept as backups, and its plan for GOES-19's handover for where GOES-17 is kept; and the page of the GOES-R spacecraft and the imager page for their mass and their full picture of the Earth.
• The telescopes and the pioneers still in orbit: ESA's XMM-Newton fact sheet, with its pages on the mirrors and the light it sees, and its Cheops overview, with its pages on the spacecraft, the light it sees and who flies it; NASA's Fermi mission page, Fermi overview and page on its main instrument; NASA's archive of spacecraft, the NSSDCA, for Fermi, TIROS-1, Telstar 1, Alouette 1, Syncom 3, Dong Fang Hong 1 and INTASAT; NOAA's anniversary of TIROS-1 and NASA's page on it; NASA's history of Telstar and of the first communications satellites, the Smithsonian's Telstar backup, and the IEEE's milestone of the first transatlantic television for Telstar's faces; Boeing's page on Syncom 3, which Hughes, now Boeing, built; the Canadian Space Agency's page on Alouette; the China National Space Administration's page on Dong Fang Hong 1, the China Academy of Space Technology's page on building it, and Xinhua's reports of 2020 and 2016 for its size and shape; and INTA's fiftieth anniversary of INTASAT and press release on it.
• The communications satellites, from their operators and filings:
  • BlueWalker 3: AST SpaceMobile's BlueWalker 3 page, its announcements of the launch and of the array's unfolding, and its orbital debris report to the FCC for its design life; its mass is Gunter's Space Page's, since AST states none.
  • Amazonas Nexus: Hispasat's fleet page and its launch-day release.
  • ARSAT-1: ARSAT's page of its geostationary satellites, its post for its nineteenth anniversary for the slot, its former ARSAT-1 page, as archived, for what it carries, its page about itself, and the builder INVAP's ARSAT-1 page for its mass.
  • Astra 1N: SES's fleet map and its launch release, which SES keeps no copy of since 2021.
  • Hotbird 13F: Eutelsat's 13° East page and brochure, its launch release and its release on ordering it for its mass.
  • Morelos 3: the releases of Mexico's Ministry of Communications and Transport on its countdown, launch and arrival at its slot, and the Mexsat operator's memoir for its slot to the tenth of a degree, and the Mexsat page of Finabien, which carries that operator's pages today, for its services.
• The other Earth observers, from their operators:
  • Envisat: ESA's declaration of the end of its mission and its operations page for the day contact was lost, and ESA Earth Online's overview of the mission for its mass and its full picture of the Earth.
  • Aqua: NASA's About Aqua page for its launch and mass, the Aqua mission page and its status page, and the MODIS page for its full picture of the Earth.
  • Suomi NPP: NASA's mission page and the Earth Observatory's articles on its launch and its map of the night lights, NASA Goddard's former project page, as archived, for its mass, and NOAA's Joint Polar Satellite System page and notice of the end of its data.
  • SMAP: NASA's mission page, its launch release, its launch press kit for its mass and antenna, and its word on the end of the radar.
  • ALOS-2: JAXA's launch release and project page, and its Earth Observation Research Center's ALOS page and specifications.
  • NISAR: NASA's quick facts and launch release, and ISRO's mission page and launch page for its mass.
  • Landsat 8: NASA's mission page and mission details, the USGS's Landsat 8 page, and the mission's 2013 press kit for its mass.
  • SAOCOM 1A: CONAE's SAOCOM mission page and launch announcement, and its article on SAOCOM's part in the SIASGE system for its mass, in Spanish.
  • PAZ: Hisdesat's PAZ page and Earth observation page, the word of Spain's Ministry of Defence, its main customer, on its successor, and ESA's PAZ page.
  • WorldView-3: Vantor's datasheet, constellation page and announcement of its new name, and DigitalGlobe's launch release.

Masses: GCAT

The mass of a satellite, a rocket body or a fragment the site writes no fact about comes from GCAT, the general catalogue of everything launched that the astronomer Jonathan McDowell keeps, by the same catalogue numbers the orbital elements are fetched by. A mass the site writes by hand, above, wins over GCAT's, which gives each module of a station on its own: its figure for the ISS is one module's. GCAT is licensed under CC BY 4.0, and the API's Catalogue answer carries its credit beside the masses, as this page does: “Masses: data from J. McDowell, planet4589.org, licensed CC BY 4.0”. The live map does not show the masses themselves: it draws each satellite and rocket body at one of three sizes by the band its mass falls in, which changes GCAT's figures, as its licence asks this page to say.

Launches: The Space Devs’ Launch Library 2

The launches on the Next launches page come from Launch Library 2, the database of launches The Space Devs keep from the providers' own announcements and their community's, read every hour: the rocket, the pad, the provider, the time with how exactly it is stated, the status, the payloads and the official webcast. Its terms leave the data free to use in any way, ask that it not be passed on without adding something of their own, and encourage attribution without requiring it; the page gives it all the same, in the sentence “Launches from The Space Devs’ Launch Library 2”, and so does the API's answer. Launch Library does not guarantee the data's accuracy, and a date is the provider's latest: the page shows each one only as exactly as it is stated, and says when it last moved. The descriptions Launch Library writes are not passed on, and a crew is counted, never named. A payload is matched to Space-Track's catalogue by its launch's international designator once the catalogue lists it.

Land and cities: Natural Earth

The coastlines, borders and names on the map and the list of cities with a page come from Natural Earth, a public domain dataset. The borders and names follow Natural Earth's default view of the world, and the lines it marks as disputed are not drawn. So do the names of the country or the sea a satellite is over, which the API gives with each position, in English and in Spanish.

Time zones

Each city's time zone is found at its centre in the boundaries of the timezone-boundary-builder project, made from OpenStreetMap data: © OpenStreetMap contributors, available under the Open Database License.

Built with

Positions are propagated with satellite.js, the Sun and the Earth's rotation come from astronomy-engine, and the map is drawn by MapLibre GL JS.

Licence of the answers

Everything Orbinauts hands out, on the pages and from the API, is licensed under Creative Commons Attribution 4.0 International (CC BY 4.0): the positions, the passes, the elements it republishes and the dataset of cities. You may copy, share and build on them, for any purpose, as long as you show the credit line:

Data: Orbinauts, orbits from Space-Track

The line names both the source that computed the answer and the catalogue the orbit came from, and so meets Space-Track's citation condition on your behalf. The API repeats it in the X-Attribution header of every response, and the API reference names the licence. The licence covers what Orbinauts computes and compiles; the elements themselves remain Space-Track's, passed on under the approval above. The site's code, its name and its logo are not covered. The terms of use say the rest.