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Auspex
How it works

From orbital elements to an answer.

The short version: real data, real maths, a playful voice on top.

1. The data

Auspex downloads the public orbital elements for every active satellite from CelesTrak, plus the satellite catalogue for owner and launch date. CelesTrak asks for no more than one download of each data set every two hours, so the server keeps its own copy and refreshes it on that schedule. Visitors never trigger a download.

Satellite types come from CelesTrak's own group lists: internet constellations, communications, navigation, weather, science and Earth observation, space stations and military. A satellite that is in none of those lists is shown as other.

2. The motion

Your browser runs SGP4, the standard model for these elements, in a background worker. It works out every satellite's position about once a second and the globe blends smoothly between those positions on the graphics card. Phones get a lighter set so they stay smooth. SGP4 positions are typically good to a few kilometres for fresh elements, which is far finer than the globe can show.

3. Your sky

Your location comes from your browser (if you allow it) or from a city you pick. It is rounded to about 10 km before it is stored or sent. The server computes the height above your horizon of every catalogued satellite and the highest one answers. Holders can pick any satellite that is up.

The pass you see (rise, highest point, set) and the ground track are computed from the same elements. A pass is marked naked-eye when the satellite is in sunlight, the Sun is at least 6 degrees below your horizon and the satellite is at least 10 degrees up.

4. The answer

Your question and a short sheet of real facts about the satellite (its name, class, owner, launch date, height, speed and where it is in your sky) go to a language model with a voice for that class of satellite. Your location is not part of it.

The model can call tools before it answers: what is overhead, a satellite lookup, passes with naked-eye visibility, constellation counts, Starlink trains, upcoming launches, cloud cover from MET Norway and close approaches from CelesTrak SOCRATES. The tools run on the server and use your rounded location there; the model never sees coordinates. It gets at most four rounds of tool calls per question, and every call counts against the daily budget. Any sentence with a number that does not appear in the facts or the tool results is removed before you see it, and the answer shows which sources it read.

It is a persona. The satellite is not thinking and nothing here is a superintelligence. Questions that look like attempts to rewrite the instructions are turned away before they reach the model, and answers are cleaned to plain text.

5. Agents

  • Watch alerts. Write what you want, for example “when the ISS passes and the sky is clear”. Fixed rules read the sentence first; the language model only helps when the rules cannot. You confirm the rule, and a worker checks it against real passes and the cloud forecast and sends a web push a few minutes before. Visitors get 1 active watch, holders 10.
  • Starlink trains. A train is a Starlink launch from the last 16 days whose satellites are still below 480 km and bunched together, read from launch dates in the satellite catalogue and the current orbits.
  • Close calls. Once a day the server downloads CelesTrak's SOCRATES list of predicted close approaches and keeps the closest ones for the next days. Pairs drifting together slower than 50 m/s are left out.
  • Sky API and MCP. The same tools as a REST API and an MCP server, with a small anonymous limit and higher limits for holder keys. Keys are stored only as hashes. See the API page.

6. Limits

  • Visitors get a few free questions a day, holders more. There is also a short pause between questions.
  • The site has a hard daily budget for answers. When it is used up, the uplink rests until midnight UTC.
  • Each answer gets its own link and card. Whoever asked can delete it.

7. Sources

  • Orbital elements, catalogue and group lists: CelesTrak.
  • Upcoming launches: Launch Library 2 by The Space Devs, cached on the server.
  • Cloud cover: MET Norway Locationforecast, CC BY 4.0, cached per rounded location.
  • Close approaches: CelesTrak SOCRATES Plus, downloaded once a day.
  • Land outlines: Natural Earth.
  • Orbital compute board: each fact links to its own source on the compute page.