Astronomy Oracle

io.github.gregarioPublished by GitHub account gregariov0.1.0Updated Oct 24, 2026

Astronomical catalog data and observing session planner. 13,000+ objects from OpenNGC.

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Overview

AI-generated overview

A local MCP server that gives assistants an offline OpenNGC deep-sky catalog and deterministic astronomy math for object lookup, catalog search and observing-s-

What you can do
Look up a celestial object by Messier, NGC/IC designation or common name, with optional altitude/azimuth and rise/transit/set times for a location and date. Search and filter the catalog by object type, constellation, magnitude range, angular size or catalog membership, returning a table sorted by brightness. Plan an observing session for a location and date, grouping the best objects into evening, midnight and pre-dawn windows scored by observability.
When to use it
Useful when an assistant needs accurate deep-sky object data or visibility calculations instead of guessing magnitudes and coordinates, or when planning a night of observing for a given place and date.
Requirements
Runs locally over stdio, typically via npx or a global npm install, so Node.js is needed. No accounts, API keys or network access are required; all catalog data and calculations are bundled and local.
Before you install
Read-only lookups and calculations; no credentials, payments or data writes are involved. Catalog data comes from OpenNGC under CC-BY-SA 4.0, so attribution and share-alike terms apply to reuse of the data.

Installation

In SourceWeft

  1. Open Astronomy Oracle in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Desktop only via STDIO. STDIO servers start a local process, so they need the SourceWeft desktop host.

Other MCP clients

Follow the launch instructions in the repository.

README

[License: MIT] [npm version] [npm downloads] [Node.js 18+] [MCP Compatible] [Sponsor] [astronomy-oracle MCP server]

[astronomy-oracle MCP server]

Astronomy Oracle

Accurate astronomical catalog data and observing session planner for LLM assistants. Stops hallucinated magnitudes, coordinates, and visibility.

Features

  • 3 tools for object lookup, catalog search, and observing session planning
  • 13,000+ deep-sky objects from the OpenNGC catalog (NGC, IC, Messier, and addendum objects)
  • Deterministic astronomy math — Julian dates, sidereal time, alt/az conversion, rise/transit/set times
  • Zero network dependency — all data is bundled, all calculations are local

Install

Run directly with npx:

bash
npx astronomy-oracle

Or install globally:

bash
npm install -g astronomy-oracle

Configuration

Claude Desktop

Add to your claude_desktop_config.json:

json
{  "mcpServers": {    "astronomy-oracle": {      "command": "npx",      "args": ["-y", "astronomy-oracle"]    }  }}

Claude Code

bash
claude mcp add astronomy-oracle -- npx -y astronomy-oracle

Tool Reference

lookup_object

Look up a celestial object by Messier number, NGC/IC designation, or common name. Optionally compute visibility from a given location and time.

json
{  "name": "lookup_object",  "arguments": {    "name": "M31",    "latitude": 51.5,    "longitude": -0.1,    "date": "2025-06-15T22:00:00Z"  }}

Returns detailed object data: type, coordinates (RA/Dec), magnitude, angular size, surface brightness, Hubble type, cross-references, and (when location is provided) current altitude/azimuth with rise/transit/set times.

search_objects

Search and filter the catalog by type, constellation, magnitude range, angular size, or catalog membership.

json
{  "name": "search_objects",  "arguments": {    "type": "PN",    "constellation": "Lyr",    "maxMagnitude": 12.0,    "limit": 10  }}

Returns a formatted table of matching objects sorted by brightness. Supports filtering by object type (Galaxy, Planetary Nebula, Open Cluster, etc.), constellation, magnitude range, minimum angular size, and catalog (Messier, Caldwell, NGC, IC).

plan_session

Generate an observing session plan for a given location and date. Returns the best objects to observe grouped by time window.

json
{  "name": "plan_session",  "arguments": {    "latitude": 40.7,    "longitude": -74.0,    "date": "2025-03-20",    "minAltitude": 20,    "maxMagnitude": 10.0,    "types": ["G", "PN", "GCl"]  }}

Returns objects grouped into three windows (evening, midnight, pre-dawn), scored by observability based on altitude, magnitude, and angular size.

Data Sources

SourceLicenseDescription
OpenNGCCC-BY-SA 4.0NGC/IC/Messier catalog with coordinates, magnitudes, dimensions, and cross-references

The OpenNGC data is included under the Creative Commons Attribution-ShareAlike 4.0 International License. See the OpenNGC repository for full attribution.

Development

bash
# Run testsnpm test
# Buildnpm run build
# Run in development mode (tsx)npm run dev
# Open MCP Inspectornpm run inspect

License

MIT for code. CC-BY-SA 4.0 for OpenNGC data.

Source: README.md at commit 7b5e6d7

Tools

0
SourceWeft has not started this package in its sandbox yet, so its tools are not known.

Version history

1
  1. v0.1.0LatestSep 16, 2026

Score

50% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 days25 pts

    Keep the endpoint answering the MCP handshake; SourceWeft probes it every 30 days.

  • Auth declared10 pts

    Declare the credential headers in the registry entry, or keep the endpoint answering the probe so its auth can be classified.

  • Tools listed15 pts

    Answer tools/list without a credential, or ship a package that starts in a sandbox without one.

  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts
  • License10 pts