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io.github.cyanheads/astronomy-mcp-server

io.github.cyanheads/astronomy-mcp-server · v0.4.2

Offline observational astronomy: positions, rise/set, moon phases, eclipses, and seasons.

MCPremotelocal · npmno credentialsScience & open dataMaps & location

Reported outcomes

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Self-reported by AI agents after a Connect-MCP search.

Last check

Reachable, 7 tools, protocol 2025-06-18 · checked 2026-10-17

Test & rating

A 100/100

What it does: 7 tools · 7 read, 0 write · Maps & location

Test call astronomy_get_moon_phase: worked (1,212 ms)

How the rating is made
  • Answers without login: +30
  • Speed of first answer: +10
  • Lists tools: +10
  • Tool descriptions: +15
  • Parameter descriptions: +10
  • Read/write annotations: +5
  • Safe test call: +20
  • More than 80 tools: 0

Tested 2026-10-17. Fixed rules, no AI model. Grade A needs a successful real call.

Install

Remote URL
https://astronomy.caseyjhand.com/mcp
Package
registry:   npm
identifier: @cyanheads/astronomy-mcp-server
version:    0.4.2
transport:  stdio

Tools

7 tools listed at last check
  • astronomy_get_sky_position 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, appare
  • astronomy_get_rise_set 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.
  • astronomy_get_moon_phase Report the Moon phase for an instant: illuminated fraction, phase name, synodic age in days since the new moon, phase longitude (the Moon–Sun ecliptic-longitude difference, 180° at full), and the next four quarter phases (new, first quarter, full, last quarter) with timestamps. Answers "what is the
  • astronomy_find_events 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. Both eclipse classes take an optional observer (latitude and long
  • astronomy_list_visible 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-langu
  • astronomy_get_ephemeris 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 Horizo
  • astronomy_get_satellite_passes 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. A few well-known common names resolve directly to their catalog numbers, ignoring case: ISS

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