Usno Astronomy MCP server

@pipeworx/usno-astronomy

Solar eclipses, local eclipse circumstances, Moon phases and the seasons from the US Naval Observatory's Astronomical Applications API. Answers "when is the next solar eclipse", "what time does the eclipse start in Madrid", "when is the next full moon" and "when is the summer solstice" from the official ephemeris.

Part of Pipeworx — an MCP gateway connecting AI agents to 1558+ live data sources.

Tools

type (total, annular, partial, hybrid). With no arguments it returns the next eclipse after today. Lunar eclipses are not published by this API.

• usnosolareclipses(year?) — the solar eclipses in a year with date and

looks like from one place: magnitude, obscuration, duration, and the UT time, Sun altitude and azimuth of each contact. found:false with reason:"not_visible" when the eclipse cannot be seen from there.

• usnoeclipsecircumstances(date, lat, lon, height?) — what a solar eclipse

Full Moon and Last Quarter in a year, or the next count phases from a date, plus nextfullmoon / nextnewmoon.

• usnomoonphases(year? | date?, count?) — every New Moon, First Quarter,

year, with northern-hemisphere season names attached.

• usno_seasons(year?) — equinoxes, solstices, perihelion and aphelion for a

Auth

Keyless.

Data sources

• — solar eclipses in a year.
• — local circumstances.
• and /api/moon/phases/date?date=YYYY-MM-DD&nump=N — Moon phases.
• — seasons.

Things the next person would otherwise rediscover:

whose body is {"error": ...}. Every error, including "eclipse not visible from selected location", comes back as 200 + error, so the pack reads the body rather than the status.

• All times are UT1, never local. Every response carries time_note.
• Years are limited to 1800–2050; USNO refuses others with an HTTP 200

supply valid coordinates" — pass coords=lat,lon and resolve place names first.

• height must be an integer number of metres; a decimal is rejected.
• The loc= place-name form of the circumstances endpoint answers "Please

TLS (measured 2026-09-10, 6–22 s per call). The gateway caches this pack's answers for a week, which is honest for a fixed ephemeris.

• There is no lunar eclipse endpoint (/api/eclipses/lunar/* is 404).
• USNO's front end can take 3 s to accept a TCP connection and 6 s more for

Quick Start

Add to your MCP client (Claude Desktop, Cursor, Windsurf, etc.):

{
  "mcpServers": {
    "usno-astronomy": {
      "url": "https://gateway.pipeworx.io/usno-astronomy/mcp"
    }
  }
}

What this endpoint actually serves

tools/list at https://gateway.pipeworx.io/usno-astronomy/mcp returns the tools in the table above plus the shared Pipeworx meta-tools — askpipeworx, discovertools, search_within, remember/recall and the rest of the gateway-wide set. So the tool count you see is larger than this table: a single-pack endpoint currently lists roughly 30 shared tools alongside the pack's own. The connection's initialize response states its exact scope, and is the authoritative answer for a given day.

This is deliberate, not multiplexing by accident. The meta-tools are what let a scoped connection answer a question this pack does not cover — via ask_pipeworx, which routes across the whole catalog — without you adding a second MCP server. There is currently no way to mount a pack endpoint without them; if the extra schemas cost you more context than the routing is worth, connect to the full gateway once rather than to several pack endpoints.

Or connect to the full Pipeworx gateway to get every pack's tools listed directly, instead of just this one's:

Shortened. The full README is on GitHub.