Platform

Package: astronomy-mcp

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Status
Description: A local astronomy MCP server built on [Skyfield](https://rhodesmill.org/skyfield/).
Port: —
Venv: venv present /Users/friedrichstr/ai-mac-studio/development/astronomy-mcp/.venv/bin/python
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astronomy-mcp/
  src/
    astronomy_mcp/
  de421.bsp
  pyproject.toml
  README.md
  SKILL.md
  star-chart.html
  uv.lock
Register Info
Status: active
Skills: SKILL.md
Documentation
Documentation
README

Astronomy MCP

A local astronomy MCP server built on Skyfield. It computes topocentric horizon coordinates (azimuth / altitude) of planets and bright stars (magnitude ≤ ~5), resolves star names, and is designed to correlate historical observation texts against actual sky positions.

Overview

  • Ephemeris (src/astronomy_mcp/ephemeris.py) — loads de421.bsp (planets + Moon) and the Hipparcos bright-star catalog (mag ≤ 5).
  • Stars (src/astronomy_mcp/stars.py) — curated bright-star database with common / Bayer / Flamsteed / HIP designations.
  • Observations (src/astronomy_mcp/observations.py) — horizon-coordinate computation for a given observer, place and time.
  • Server (src/astronomy_mcp/server.py) — the MCP tool surface.
  • Visualization (src/astronomy_mcp/visualization.py + render.py) — D3 star-chart generation (equatorial / horizontal / ecliptic frames).

Install

cd development/astronomy-mcp
uv sync

First run downloads the ephemeris (de421.bsp) and Hipparcos catalog into src/astronomy_mcp/data/.

Usage

Demo (one-off computation)

uv run astronomy-mcp --demo

D3 star chart

uv run astronomy-mcp --chart --lat 52.52 --lon 13.405 --utc 2026-10-01T20:00:00Z --out star-chart.html
open star-chart.html

Renders a self-contained HTML star map (D3 via CDN) with bright stars sized by magnitude, planets, and a switchable coordinate grid (equatorial / horizontal / ecliptic).

MCP server (stdio)

uv run astronomy-mcp

The server reads JSON-RPC lines on stdin. Tools:

Tool Purpose
planet_horizon(lat_deg, lon_deg, utc, planet, elevation_m) azimuth/altitude of a planet
star_horizon(lat_deg, lon_deg, utc, star, elevation_m) azimuth/altitude of a bright star
list_stars the bright-star catalog
resolve_star(name) resolve a name/designation to a star record

Coordinate frames

Positions are topocentric horizon coordinates (azimuth measured from north, altitude above the horizon). Equatorial / ecliptic / horizontal grids are the visualization layer (see the companion astronomical-star-map-visualization work-order).

Historical coverage

  • Ephemeris spans roughly −4000 … today (JPL DE421).
  • For eclipse / archaeological work, a long-range model can be added (documented future work).

Partitur integration

A Partitur skill generalizes observation types from Kepler's Astronomia Nova and Copernicus' De revolutionibus so new PDAI documents can be analyzed and correlated. (See the work-order in 5-work-order/astronomy-mcp-server.md.)

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