{ "specificationVersion": "0.21", "aid": "cyclecalcs.com:astronomy", "name": "CycleCalcs", "type": "Index", "kind": "company", "description": "CycleCalcs publishes a read-only astronomy API and an MCP server over the same engine: sun and moon times, moon phases, planet positions and visibility, eclipses, seasons, retrogrades, conjunctions, twilight and dark-sky windows. Answers are computed live with the MIT-licensed Astronomy Engine and state their frame, epoch, time scale and refraction model on every response. Pure positional astronomy: no astrology and no claims that sky events affect people or Earth.", "image": "https://www.cyclecalcs.com/assets/og-card.png?v=2", "url": "https://www.cyclecalcs.com/apis.json", "created": "2026-08-09", "modified": "2026-08-09", "tags": [ "Astronomy", "Space", "Science", "Ephemeris", "Sun", "Moon", "Planets", "Eclipses", "Time", "Calendar" ], "apis": [ { "aid": "cyclecalcs.com:astronomy-api-v2", "name": "CycleCalcs Astronomy API", "description": "A read-only astronomy API of 29 endpoints that returns the named answer and the numbers behind it, not raw ephemeris: moon phase and illumination, sunrise, sunset and twilight, planet positions and a visibility board, rise and set times, eclipses, apsides, lunar nodes and libration, seasons, retrograde stations, conjunctions and angular separation, sidereal time, the equation of time, Jupiter's Galilean moons, sky quality and dark-sky windows, place lookup, and a one-call sky snapshot for a location and moment. Every response states its frame, epoch, time scale and refraction model. Positions are arcminute class for the Sun, Moon and planets from 1700 to 2200. No key is required for the free tier; paid volume tiers are sold through RapidAPI. JSON over HTTPS, GET only, with RFC 9457 problem documents for errors.", "image": "https://www.cyclecalcs.com/assets/og-card.png?v=2", "humanURL": "https://www.cyclecalcs.com/api.html", "baseURL": "https://www.cyclecalcs.com/v2", "version": "2.0.0", "tags": [ "Astronomy", "Space", "Science", "Ephemeris", "Sun", "Moon", "Planets", "Eclipses", "Time", "Geolocation" ], "properties": [ { "type": "OpenAPI", "name": "OpenAPI 3.1 description", "description": "Generated from the shipped route table, so it describes the deployed API rather than a hand-maintained copy of it.", "url": "https://www.cyclecalcs.com/v2/openapi.json", "mediaType": "application/json" }, { "type": "Documentation", "name": "API reference", "description": "Every endpoint with its parameters, response shape and worked examples.", "url": "https://www.cyclecalcs.com/api/reference.html" }, { "type": "GettingStarted", "name": "Start here", "description": "What the API returns, how it differs from a raw ephemeris service, and a first request you can paste into a terminal.", "url": "https://www.cyclecalcs.com/api.html" }, { "type": "LlmsText", "name": "llms-full.txt for the API", "description": "The full API contract in one plain-text file written for language models and coding agents.", "url": "https://www.cyclecalcs.com/v2/llms-full.txt", "mediaType": "text/plain" }, { "type": "MCPServer", "name": "CycleCalcs Astronomy MCP server", "description": "Streamable HTTP MCP endpoint exposing 11 astronomy tools over the same engine as the REST API. Authenticates with a RapidAPI key sent as a bearer token; the Basic plan is free.", "url": "https://www.cyclecalcs.com/mcp" }, { "type": "Documentation", "name": "MCP server guide", "description": "The tool list, the client configuration, and how the MCP surface maps onto the REST endpoints.", "url": "https://www.cyclecalcs.com/api/mcp.html" }, { "type": "Authentication", "name": "Keys and tiers", "description": "The free tier is keyless. Paid tiers authenticate at the RapidAPI gateway, never with a query parameter.", "url": "https://www.cyclecalcs.com/api/keys.html" }, { "type": "Plans", "name": "Plans on RapidAPI", "url": "https://rapidapi.com/info-8KZIhinZ9/api/cyclecalcs-astronomy-api3" }, { "type": "Pricing", "name": "Pricing", "description": "Basic is free and keyless. Pro, Ultra and Mega are 5, 9 and 15 US dollars a month through RapidAPI.", "url": "https://rapidapi.com/info-8KZIhinZ9/api/cyclecalcs-astronomy-api3" }, { "type": "RateLimits", "name": "Rate limits and range caps", "description": "Limits are per caller, not global: 300 requests a minute, 2,000 an hour and 5,000 a day on the free tier, with the rate-limit headers and the 429 behaviour documented.", "url": "https://www.cyclecalcs.com/api/status.html" }, { "type": "Documentation", "name": "Errors", "description": "Every error is an RFC 9457 problem document with a stable type URL.", "url": "https://www.cyclecalcs.com/api/errors.html" }, { "type": "Documentation", "name": "Accuracy and limits", "description": "What the numbers are good for, where they degrade, and how they were checked.", "url": "https://www.cyclecalcs.com/api/accuracy.html" }, { "type": "Documentation", "name": "Versioning policy", "description": "What counts as additive, what counts as breaking, how to pin an integration, and the deprecation policy. Version 1 stays frozen for existing callers.", "url": "https://www.cyclecalcs.com/api/versioning.html" } ], "contact": [ { "FN": "CycleCalcs", "email": "info@cyclecalcs.com", "url": "https://www.cyclecalcs.com/api.html" } ] } ], "common": [ { "type": "TermsOfService", "name": "API terms", "url": "https://www.cyclecalcs.com/api/terms.html" }, { "type": "PrivacyPolicy", "name": "Privacy policy", "url": "https://www.cyclecalcs.com/privacy.html" }, { "type": "LlmsText", "name": "Site llms.txt", "description": "The whole site described for language models: the sky tools, the cycle references and the calculators alongside the API.", "url": "https://www.cyclecalcs.com/llms.txt", "mediaType": "text/plain" }, { "type": "Documentation", "name": "Attribution and credits", "description": "The data sources behind the answers and the licence obligations owed to each.", "url": "https://www.cyclecalcs.com/CREDITS.md" } ], "maintainers": [ { "FN": "CycleCalcs", "email": "info@cyclecalcs.com", "url": "https://www.cyclecalcs.com/" } ] }