API & MCP

Everything a person can do on Skyfold Satellite Pass Predictor, a program or AI agent can do with the same inputs and get the identical result.

HTTP API

POST https://skyfoldsatellitepasses.usefulweb.app/api/v1/calculate – run Skyfold Satellite Pass Predictor
GET https://skyfoldsatellitepasses.usefulweb.app/api/v1/tool – inputs, output schema, examples
OpenAPI 3.1: /openapi.json · /openapi.yaml
Errors: application/problem+json; 422 includes per-field errors.

Skyfold Satellite Pass Predictor

Predicts rise, culmination and set of satellites over a place with an SGP4/SDP4 propagator verified against the published Vallado test cases, and marks the naked-eye visible part (satellite in sunlight, sky dark). Paste elements or fetch them from CelesTrak.

Inputs of Skyfold Satellite Pass Predictor
Field	Type	Default	Description
`location`	text	"52.0907, 5.1214"	Location (latitude, longitude). Decimal degrees such as 52.09, 5.12 (north and east positive), or DMS, UTM, MGRS, Maidenhead or a plus code.
`elevation`	number	0	Elevation above sea level
`timeZone`	text	"Europe/Amsterdam"	Time zone. IANA name such as Europe/Berlin or America/New_York, or a fixed offset such as UTC+2.
`date`	date	"2026-11-07"	Local date
`time`	time	"18:00"	Local time
`source`	select (paste, celestrak)	"paste"	Elements
`tle`	textarea	"ISS (ZARYA)\n1 25544U 98067A 26311.20783432 .00014294 00000+0 26479-3 0 9	Two-line elements (TLE). One or more sets: an optional name line, then line 1 and line 2.
`catalogNumbers`	text	"25544"	NORAD catalogue numbers (CelesTrak). Up to 5 numbers separated by commas, for example 25544 for the ISS. Used when Elements is set to CelesTrak.
`group`	select (, stations, visual, amateur, weather, science)	—	Or a CelesTrak group
`days`	number	2	Days to search
`minElevation`	number	10	Minimum elevation
`visibleOnly`	boolean	false	Only naked-eye visible passes

Example request

ISS over Utrecht (elements of 7 November 2026)

curl -X POST https://skyfoldsatellitepasses.usefulweb.app/api/v1/calculate -H 'content-type: application/json' -d '{"location":"52.0907, 5.1214","timeZone":"Europe/Amsterdam","date":"2026-11-07","time":"18:00","source":"paste","tle":"ISS (ZARYA)\n1 25544U 98067A   26311.20783432  .00014294  00000+0  26479-3 0  9992\n2 25544  51.6321 312.3516 0007247 357.8301   2.2655 15.49235271593925","days":2,"minElevation":10,"visibleOnly":false}'

Every result contains

inputs (normalised, defaults applied), summary, result (validated against the published schema), units, assumptions, sources, warnings, computedAt and links.

MCP (Model Context Protocol)

Streamable HTTP endpoint: https://skyfoldsatellitepasses.usefulweb.app/mcp – protocol revisions 2026-07-28 (stateless) and 2025-11-25 / 2025-06-18 / 2025-03-26 (initialize handshake).
Tools: skyfold_satellite_passes
Local stdio connector: node src/mcp-stdio.ts --tool=skyfold-satellite-passes

{
  "mcpServers": {
    "skyfold-satellite-passes": { "type": "http", "url": "https://skyfoldsatellitepasses.usefulweb.app/mcp" }
  }
}