{ "opencollection": "1.0.0", "info": { "name": "CycleCalcs Astronomy Equation Of Time API", "version": "2.0.0" }, "items": [ { "info": { "name": "Equation Of Time", "type": "folder" }, "items": [ { "info": { "name": "How far a sundial runs ahead of or behind the clock, from the real Sun rather than a day-of-year series, with the Sun place that makes a range query an analemma", "type": "http" }, "http": { "method": "GET", "url": "https://www.cyclecalcs.com/v2/equation-of-time", "params": [ { "name": "at", "value": "2026-11-14T21:30:00Z", "type": "query", "description": "The instant to evaluate. ISO 8601: a date (2026-06-21), or a date and time with an optional seconds, fraction and either Z or a numeric UTC offset. No offset and no `tz` reads as UTC. Reliable from 1700 to 2200." }, { "name": "start", "value": "2026-01-01", "type": "query", "description": "The start of a range query, inclusive. ISO 8601: a date (2026-06-21), or a date and time with an optional seconds, fraction and either Z or a numeric UTC offset. No offset and no `tz` reads as UTC. Reliable from 1700 to 2200." }, { "name": "end", "value": "2027-01-01", "type": "query", "description": "The end of a range query. A row landing exactly on `end` IS returned: the window is [start, end]. Every endpoint's rule is published as data under limits.range_boundaries in /v2/conventions. ISO 8601: a date (2026-06-21), or a date and time with an optional seconds, fraction and either Z or a numeric UTC offset. No offset and no `tz` reads as UTC. Reliable from 1700 to 2200." }, { "name": "step", "value": "1d", "type": "query", "description": "Sampling stride for a range query: a number plus a unit, one of min, m (minute), h (hour), d (day), w (week), mo (month) or y (year), for example 1h, 6h or 1d. Resolves to at least 1 minute and at most 1 year. Needs `start`. This is the generic grammar; an endpoint that narrows it documents the narrowing on its own `step` parameter, and /v2/conventions publishes every narrowing under limits.step_grammar.endpoint_policies." }, { "name": "count", "value": "30", "type": "query", "description": "Number of rows to return from a range query, counted forward from `start`. Mutually exclusive with `end`." }, { "name": "lat", "value": "51.4778", "type": "query", "description": "Latitude in decimal degrees, north positive. No compass suffix (do not append N or S). Required together with lon, or neither." }, { "name": "lon", "value": "-0.0015", "type": "query", "description": "Longitude in decimal degrees, east positive. No compass suffix (do not append E or W). Required together with lat, or neither." }, { "name": "elevation_m", "value": "11", "type": "query", "description": "Observer elevation above mean sea level, in metres. Raises the observer on a locally flat plateau; sea-horizon dip is not modelled." }, { "name": "place", "value": "London", "type": "query", "description": "A place name (place=London), a name with a country (place=Cambridge,GB), or a stable identifier from GET /v2/places (place=id:us-n35198-w111651). Supplies lat, lon and, unless tz is also sent, the time zone. Mutually exclusive with sending lat and lon directly. Withheld unless GET /v2 reports capabilities.place_lookup true." }, { "name": "place_strategy", "value": "best", "type": "query", "description": "best guesses the intended place when a name is ambiguous and reports the guess as a warning. error refuses an ambiguous name with 400 AMBIGUOUS_PLACE and the candidates in `supported`. Only meaningful with `place`." }, { "name": "tz", "value": "Europe/London", "type": "query", "description": "An IANA time zone name, for example Europe/London or America/Chicago. Numeric offsets and abbreviations are not accepted. Governs how a date-only or offset-free `at`/`start`/`end` is read, and how local instants are rendered when time_format=iso." }, { "name": "ambiguous", "value": "first", "type": "query", "description": "How to resolve a local time that a clock repeated, such as the return from daylight saving. error refuses with 409 AMBIGUOUS_LOCAL_TIME." }, { "name": "nonexistent", "value": "error", "type": "query", "description": "How to resolve a local time that never happened, such as inside a spring-forward gap. error refuses with 400 NONEXISTENT_LOCAL_TIME." }, { "name": "include", "value": "basic", "type": "query", "description": "Comma-separated optional blocks to include. Omit for the endpoint default set." }, { "name": "time_format", "value": "iso", "type": "query", "description": "How instants are rendered: iso for ISO 8601 strings carrying the effective offset, or unix for integer seconds since the epoch." }, { "name": "format", "value": "json", "type": "query", "description": "Response representation. Each endpoint serves a subset of json, csv and txt; see that operation's description for the exact list, or GET /v2 for every endpoint's formats array. An unsupported value is 400 BAD_FORMAT with the accepted list in `supported`." }, { "name": "fields", "value": "", "type": "query", "description": "Comma-separated dot paths into `data` (for example moon.phase_name,moon.illumination) so only those fields are returned. Up to 64 paths; an array element is addressed by its object key, never by index." }, { "name": "shape", "value": "nested", "type": "query", "description": "nested returns the documented object tree. flat returns one object with dotted keys, format=json only." }, { "name": "precision", "value": "6", "type": "query", "description": "Decimal places for numeric fields." }, { "name": "pretty", "value": "1", "type": "query", "description": "Whether the JSON body is indented (1) or compact (0). Has no effect on csv or txt." }, { "name": "verbosity", "value": "full", "type": "query", "description": "full includes prose notes, frame definitions and withheld-field reasons in meta. compact keeps every value and every machine-readable name and drops the prose." } ] }, "docs": "How far a sundial runs ahead of or behind the clock, from the real Sun rather than a day-of-year series, with the Sun place that makes a range query an analemma. Formats: json, csv, txt. Example: GET /v2/equation-of-time?lon=-0.126&at=2026-11-14T21:30:00Z" } ] } ], "bundled": true }