API & MCP

Everything a person can do on Skyfold Star Map Poster, a program or AI agent can do with the same inputs and get the identical result.

HTTP API

POST https://skyfoldstarmapposter.usefulweb.app/api/v1/calculate – run Skyfold Star Map Poster
GET https://skyfoldstarmapposter.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 Star Map Poster

Draws the stars to magnitude 6.5, constellation figures, the Moon and planets exactly as they stood above a place at a local date and time, in five print styles and seven paper sizes, as a vector SVG and PDF.

Inputs of Skyfold Star Map Poster
Field	Type	Default	Description
`location`	text	"48.8566, 2.3522"	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/Paris"	Time zone. IANA name such as Europe/Berlin or America/New_York, or a fixed offset such as UTC+2.
`date`	date	"2019-06-14"	Local date
`time`	time	"23:30"	Local time
`style`	select (midnight, ivory, black, blueprint, red)	"midnight"	Style
`size`	select (a4, a3, a2, letter, in12x16, in18x24, square)	"a3"	Paper size
`magLimit`	number	6	Faintest stars (magnitude). Larger numbers show fainter stars; 6 to 6.5 is the naked-eye limit under a dark sky.
`title`	text	"The night we met"	Title
`subtitle`	text	—	Subtitle
`placeLabel`	text	"Paris, France"	Place line
`dateLabel`	text	—	Date line. Leave blank to print the local date and time.
`constellations`	boolean	true	Constellation lines
`constellationNames`	boolean	true	Constellation names
`starNames`	boolean	false	Names of the brightest stars
`planets`	boolean	true	Moon and planets
`colorStars`	boolean	false	Star colours from the B−V index

Example request

Paris, 14 June 2019, ivory print

curl -X POST https://skyfoldstarmapposter.usefulweb.app/api/v1/calculate -H 'content-type: application/json' -d '{"location":"48.8566, 2.3522","timeZone":"Europe/Paris","date":"2019-06-14","time":"23:30","style":"ivory","size":"a3","magLimit":6,"title":"The night we met","placeLabel":"Paris, France"}'

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://skyfoldstarmapposter.usefulweb.app/mcp – protocol revisions 2026-07-28 (stateless) and 2025-11-25 / 2025-06-18 / 2025-03-26 (initialize handshake).
Tools: skyfold_star_map_poster
Local stdio connector: node src/mcp-stdio.ts --tool=skyfold-star-map-poster

{
  "mcpServers": {
    "skyfold-star-map-poster": { "type": "http", "url": "https://skyfoldstarmapposter.usefulweb.app/mcp" }
  }
}