{"name":"io.github.cyanheads/astronomy-mcp-server","slug":"cyanheads-astronomy-mcp-server","title":null,"description":"Offline observational astronomy: positions, rise/set, moon phases, eclipses, and seasons.","url":"https://mcp.market/server/cyanheads-astronomy-mcp-server","rating":null,"grade":"A","score":93,"certified":false,"status":"active","category":"other","tags":[],"presence":{"score":37,"stars":3,"forks":0,"downloads_week":158,"last_push_at":"2026-09-19T17:20:01.000Z","license":"Apache-2.0"},"uptime":{"percent":100,"checks":2,"ok":2,"last_checked_at":"2026-09-19T23:10:57.541Z","last_ok_at":"2026-09-19T23:10:57.541Z","latency_ms":309},"claimed":false,"transport":"mixed","callable_via_gateway":true,"default_price_micros":0,"repository":"https://github.com/cyanheads/astronomy-mcp-server","website":null,"version":"0.2.10","remotes":[{"type":"streamable-http","url":"https://astronomy.caseyjhand.com/mcp"}],"packages":[{"registryType":"npm","registryBaseUrl":"https://registry.npmjs.org","identifier":"@cyanheads/astronomy-mcp-server","version":"0.2.10","runtimeHint":"bun","transport":{"type":"stdio"},"packageArguments":[{"value":"run","type":"positional"},{"value":"start:stdio","type":"positional"}],"environmentVariables":[{"description":"Sets the minimum log level for output (e.g., 'debug', 'info', 'warn').","format":"string","default":"info","name":"MCP_LOG_LEVEL"},{"description":"Register the astronomy_get_ephemeris tool, which fetches small-body and spacecraft ephemerides from JPL Horizons. 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Off by default; the core is keyless and offline.","format":"string","default":"false","name":"ASTRONOMY_ENABLE_HORIZONS"},{"description":"Register the astronomy_get_satellite_passes tool, which predicts visible satellite passes from CelesTrak GP element sets propagated with SGP4. Off by default.","format":"string","default":"false","name":"ASTRONOMY_ENABLE_SATELLITES"},{"description":"Fallback IANA timezone for observer-local output when a tool call omits `timezone`. Unset means UTC-only output.","format":"string","name":"ASTRONOMY_DEFAULT_TIMEZONE"}]}],"tools":[{"name":"astronomy_find_events","description":"Search forward from a start time for the next occurrences of one sky-event class, selected by the `event` enum: solar_eclipse, lunar_eclipse, equinox, solstice, moon_quarter, opposition, conjunction, max_elongation, or perigee_apogee. Only solar_eclipse takes an observer: pass latitude and longitude to get local circumstances (contact times plus `local_visible`). Every other class is geocentric and needs no location — a lunar eclipse is the same event everywhere the Moon is up, so it returns contact times and no `local_visible`. The body-relative events (opposition, conjunction, max_elongation, perigee_apogee) require a `body`: opposition applies to the superior planets (mars through pluto), conjunction to any planet, max_elongation to mercury and venus, and perigee_apogee to the moon (perigee/apogee), earth, or a planet (perihelion/aphelion). Returns the next `count` occurrences (default 1). Start defaults to now; pass an IANA `timezone` for observer-local timestamps.","write_action":false,"price_micros":0,"input_schema":{"type":"object","properties":{"event":{"type":"string","enum":["solar_eclipse","lunar_eclipse","equinox","solstice","moon_quarter","opposition","conjunction","max_elongation","perigee_apogee"],"description":"Which class of event to search for."},"start":{"description":"Search start as an ISO 8601 UTC string, e.g. \"2024-01-01T00:00:00Z\". Defaults to now. A value with no zone designator is read as UTC, not the local zone of the server process.","type":"string"},"count":{"default":1,"description":"Number of forward occurrences to return. 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When omitted, output is UTC-only.","type":"string"}},"required":["event"],"$schema":"https://json-schema.org/draft/2020-12/schema","additionalProperties":false}},{"name":"astronomy_get_ephemeris","description":"Fetch a time-series ephemeris for a small body (asteroid or comet) or spacecraft from JPL Horizons — RA/Dec, distance, and apparent magnitude over a span, optionally with observer-relative altitude/azimuth. This covers objects the in-process major-body set cannot. The designation is passed to Horizons verbatim, so it must be in a form Horizons resolves to a single record: a numbered asteroid takes a trailing-semicolon record lookup (e.g. \"433;\" for Eros, \"1;\" for Ceres), and a periodic comet takes the DES + closest-apparition form (e.g. \"DES=1P;CAP\" for Halley) — a bare name like \"433 Eros\" or \"1P/Halley\" returns no match or an ambiguous record list and is rejected. Spacecraft take their negative SPK-ID. `start` and `stop` are ISO 8601 UTC and `stop` must be after `start`; `step` is a count plus a unit of m, h, d, mo, or y, such as \"1d\", \"1h\", or \"10m\". Supplying observer latitude/longitude yields topocentric coordinates and adds alt/az — supply both or neither. This is a gated, network-backed extension (JPL Horizons is keyless but rate-limited and best-effort); large spans truncate inline at 200 rows, and the truncation notice names the exact `start` to resume from — one step past the last row returned, because Horizons includes the start instant in its output — so re-calling from there continues the series without repeating a sample. Splitting the range into smaller adjacent spans works too; keep the same step either way so no sample is lost.","write_action":false,"price_micros":0,"input_schema":{"type":"object","properties":{"designation":{"type":"string","minLength":1,"description":"JPL Horizons target, passed verbatim — use a form that resolves to one record. Numbered asteroid: trailing-semicolon record lookup, e.g. \"433;\" (Eros), \"1;\" (Ceres). Periodic comet: DES + closest-apparition flag, e.g. \"DES=1P;CAP\" (Halley), \"DES=2P;CAP\" (Encke). Spacecraft: negative SPK-ID, e.g. \"-48\" (Hubble). A bare name like \"433 Eros\" or \"1P/Halley\" fails. Look up designations at ssd.jpl.nasa.gov/tools/sbdb_lookup.html."},"latitude":{"description":"Observer latitude in decimal degrees — supply together with longitude for topocentric coordinates and alt/az. Supplying one without the other is rejected.","type":"number","minimum":-90,"maximum":90},"longitude":{"description":"Observer longitude in decimal degrees. Supply together with latitude; one without the other is rejected.","type":"number","minimum":-180,"maximum":180},"elevation":{"default":0,"description":"Observer elevation in meters above sea level. Default 0.","type":"number"},"start":{"description":"Ephemeris start as an ISO 8601 UTC string, e.g. \"2024-01-01T00:00:00Z\". Defaults to now. A value with no zone designator is read as UTC, not the local zone of the server process.","type":"string"},"stop":{"description":"Ephemeris stop as an ISO 8601 UTC string, and must be later than start. Defaults to 24 hours after start. A value with no zone designator is read as UTC, not the local zone of the server process.","type":"string"},"step":{"default":"1h","description":"Step size as a positive count plus a unit of m (minutes), h (hours), d (days), mo (months), or y (years), e.g. \"10m\", \"1h\", \"1d\". 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A value with no zone designator is read as UTC, not the local zone of the server process.","type":"string"},"timezone":{"description":"IANA timezone for localized output, e.g. \"America/Los_Angeles\". When omitted, output is UTC-only.","type":"string"}},"$schema":"https://json-schema.org/draft/2020-12/schema","additionalProperties":false}},{"name":"astronomy_get_rise_set","description":"Compute rise, set, and culmination (transit) times for a body at an observer location, plus the maximum altitude at culmination. For the Sun, also returns the three twilight pairs (civil −6°, nautical −12°, astronomical −18°) so a single call answers \"when does the sun set and when is it truly dark.\" Searches forward from `start` (default today) and returns the next `count` cycles (default 1). When the body is already above the horizon at `start`, the first cycle is the interval in progress: its `set` is the imminent one and its `rise` is null, since that rise precedes the search — so a set is never reported earlier than the rise beside it. Circumpolar or never-rises situations are reported as null rise/set fields with an explanatory note rather than an error — the fact is the answer. Default elevation is 0 m; pass an IANA `timezone` for observer-local times. This server does not geocode — resolve coordinates upstream first.","write_action":false,"price_micros":0,"input_schema":{"type":"object","properties":{"body":{"type":"string","enum":["sun","moon","mercury","venus","mars","jupiter","saturn","uranus","neptune","pluto"],"description":"The body to compute rise/set for. Twilight is included only when this is \"sun\"."},"latitude":{"type":"number","minimum":-90,"maximum":90,"description":"Observer latitude in decimal degrees, north positive."},"longitude":{"type":"number","minimum":-180,"maximum":180,"description":"Observer longitude in decimal degrees, east positive."},"elevation":{"default":0,"description":"Observer elevation in meters above sea level. Default 0.","type":"number"},"start":{"description":"Search start as an ISO 8601 UTC string, e.g. \"2024-06-21T00:00:00Z\". Defaults to now. A value with no zone designator is read as UTC, not the local zone of the server process.","type":"string"},"count":{"default":1,"description":"Number of forward rise/set cycles to return. Default 1, max 31.","type":"integer","minimum":1,"maximum":31},"timezone":{"description":"IANA timezone for localized output, e.g. \"America/Los_Angeles\". When omitted, output is UTC-only.","type":"string"}},"required":["body","latitude","longitude"],"$schema":"https://json-schema.org/draft/2020-12/schema","additionalProperties":false}},{"name":"astronomy_get_satellite_passes","description":"Predict visible passes of a satellite (e.g. the ISS, NORAD 25544) over an observer in the next `days`. Identify the satellite by exactly one of `norad_id` or `name` — supplying both, or neither, is rejected. `name` is matched as a case-insensitive substring of CelesTrak's catalog names, so it resolves only when it picks out a single object: a broader query comes back with the matching objects and their catalog numbers to choose from, and the result echoes the query that resolved it as `resolved_from_name`. Fetches the object's current GP element set from CelesTrak, propagates it with SGP4 in-process, and returns each pass's rise, peak, and set times with azimuths and the peak elevation. Only passes that are naked-eye-plausible are returned — the satellite must be sunlit at peak while the observer's sky is dark. Every returned pass rises within the requested window: a pass already underway at `start` is omitted rather than reported with `start` as its rise, so back up `start` to see it. A `start` further than about a month from the element set's epoch is rejected as out of range on that distance alone, and an element set that will not propagate to a window inside that horizon is rejected as a reentry — so an empty `passes` means only that nothing was visible. CelesTrak publishes only current element sets, so in practice `start` must be within about a month of today. NORAD catalog numbers and catalog names are found at celestrak.org or heavens-above.com. This is a gated, network-backed extension (CelesTrak is keyless but rate-limited; element sets are cached briefly). Default elevation 0 m; pass an IANA timezone for observer-local pass times.","write_action":false,"price_micros":0,"input_schema":{"type":"object","properties":{"norad_id":{"description":"NORAD catalog number of the satellite, e.g. 25544 for the ISS. Found at celestrak.org or heavens-above.com. Mutually exclusive with `name` — supply exactly one.","type":"integer","exclusiveMinimum":0,"maximum":9007199254740991},"name":{"description":"Satellite name to resolve against CelesTrak, e.g. \"ISS (ZARYA)\". Matched as a case-insensitive substring of the catalog name, so give the fullest name you have — a short one matches many objects and is rejected as ambiguous. Mutually exclusive with `norad_id` — supply exactly one.","type":"string"},"latitude":{"type":"number","minimum":-90,"maximum":90,"description":"Observer latitude in decimal degrees, north positive."},"longitude":{"type":"number","minimum":-180,"maximum":180,"description":"Observer longitude in decimal degrees, east positive."},"elevation":{"default":0,"description":"Observer elevation in meters above sea level. Default 0.","type":"number"},"days":{"default":7,"description":"Number of days ahead to search for passes. Default 7, max 10.","type":"integer","minimum":1,"maximum":10},"start":{"description":"Search start as an ISO 8601 UTC string, within about a month of the current element set's epoch — for a tracked object that epoch is hours old, so in practice within about a month of today. A start further out is rejected rather than answered from elements that no longer describe the orbit. Defaults to now. A value with no zone designator is read as UTC, not the local zone of the server process.","type":"string"},"timezone":{"description":"IANA timezone for localized pass times, e.g. \"America/Los_Angeles\". When omitted, output is UTC-only.","type":"string"}},"required":["latitude","longitude"],"$schema":"https://json-schema.org/draft/2020-12/schema","additionalProperties":false,"oneOf":[{"type":"object","required":["norad_id"],"not":{"required":["name"]}},{"type":"object","required":["name"],"not":{"required":["norad_id"]}}]}},{"name":"astronomy_get_sky_position","description":"Compute the apparent topocentric position of one solar-system body (sun, moon, mercury through neptune, pluto) or a named bright star for an observer location and instant. Returns equatorial (RA/Dec), refraction-corrected horizontal (altitude/azimuth), and ecliptic coordinates, plus distance, apparent magnitude, angular diameter, phase angle, illuminated fraction, and the constellation it falls in. For a solar-system body it also returns that body card — classification, mean radius, naked-eye visibility — the same values served at astronomy://body/{body}, so a client without resource support does not need a second surface to reach them; a catalog star has no card and the field is absent. Positions are parallax- and aberration-corrected for the given observer; default elevation is 0 m and the default time is now. Supply `star` (e.g. \"Sirius\", \"Polaris\") instead of `body` to target a catalog star; `body` is ignored when `star` is set. Pass an IANA `timezone` to also receive the observer-local time. This server does not geocode — resolve a place name to latitude/longitude upstream first.","write_action":false,"price_micros":0,"input_schema":{"type":"object","properties":{"body":{"description":"Solar-system body to locate. Omit when targeting a named star via `star`.","type":"string","enum":["sun","moon","mercury","venus","mars","jupiter","saturn","uranus","neptune","pluto"]},"star":{"description":"Named bright star to locate (common name or Bayer designation, e.g. \"Sirius\", \"Alpha Centauri\"). Takes precedence over `body`.","type":"string"},"latitude":{"type":"number","minimum":-90,"maximum":90,"description":"Observer latitude in decimal degrees, north positive."},"longitude":{"type":"number","minimum":-180,"maximum":180,"description":"Observer longitude in decimal degrees, east positive."},"elevation":{"default":0,"description":"Observer elevation in meters above sea level. Default 0.","type":"number"},"time":{"description":"Instant of observation as an ISO 8601 UTC string, e.g. \"2024-04-08T18:00:00Z\". Defaults to now. A value with no zone designator is read as UTC, not the local zone of the server process.","type":"string"},"timezone":{"description":"IANA timezone for localized output, e.g. \"America/Los_Angeles\". When omitted, output is UTC-only.","type":"string"}},"required":["latitude","longitude"],"$schema":"https://json-schema.org/draft/2020-12/schema","additionalProperties":false}},{"name":"astronomy_list_visible","description":"The one-call \"what is up right now\" answer. For an observer location and instant, iterate every naked-eye solar-system body (and, with include_stars, the bundled bright stars), compute altitude and azimuth, keep those above the horizon, rank them brightest-and-highest first, and attach a plain-language visibility note to each. The whole sky is gated by the Sun's altitude into daylight / civil / nautical / astronomical twilight / dark, returned alongside the list. `time` is a single evaluation instant, not a window — for \"tonight\" pass a time after astronomical dusk (use astronomy_get_rise_set on the sun to find it). Default elevation 0 m; use min_altitude to skip objects grazing the horizon. This server does not geocode — resolve coordinates upstream first; pass an IANA timezone for observer-local times on each body.","write_action":false,"price_micros":0,"input_schema":{"type":"object","properties":{"latitude":{"type":"number","minimum":-90,"maximum":90,"description":"Observer latitude in decimal degrees, north positive."},"longitude":{"type":"number","minimum":-180,"maximum":180,"description":"Observer longitude in decimal degrees, east positive."},"elevation":{"default":0,"description":"Observer elevation in meters above sea level. 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