io.github.cyanheads/astronomy-mcp-server vs Sidereon
io.github.cyanheads/astronomy-mcp-server is an MCP server published by cyanheads. Marketplaces we read that list it: 2 (Official MCP Registry, npm registry (MCP servers)). Sidereon is an MCP server published by neilberkman. Marketplaces we read that list it: 1 (Official MCP Registry). As of our marketplace pass on 2026-11-08. This pair was picked by a reader, not by our comparison rule, so search engines are asked not to index the page.
Where each is published
| Marketplace |  io.github.cyanheads/astronomy-mcp-server |  Sidereon |
|---|---|---|
| Official MCP Registry | Listed Version: 0.5.0 Downloads/month (npm): 1 362 Downloads/week (npm): 159 Forks (GitHub): 2 Stars (GitHub): 5 Not marked · First seen |
Listed Version: 3.0.6 Forks (GitHub): 1 Stars (GitHub): 19 Not marked · First seen |
| npm registry (MCP servers) | Listed Version: 0.5.0 Downloads/month (npm): 1 362 Downloads/week (npm): 159 Forks (GitHub): 2 Stars (GitHub): 5 Not marked · First seen |
Not listed |
Each figure is the marketplace's own and is never added up across marketplaces. A marketplace that publishes no figure shows none: no number is not zero.
The facts side by side
| Fact | io.github.cyanheads/astronomy-mcp-server | Sidereon |
|---|---|---|
| Marketplaces that list it (differs) | 2 (better) | 1 (worse) |
| Stars (GitHub) (differs) | 5 (worse) | 19 (better) |
| Forks (GitHub) (differs) | 2 (better) | 1 (worse) |
| Last release (differs) | 2026-10-29 (worse) | 2026-10-30 (better) |
| Where it runs (differs) | Remote server or your machine | On your machine (https://github.com/neilberkman/sidereon/releases/download/v3.0.6/sidereon_3.0.6.mcpb) |
| Transport (differs) | Streamable HTTP | stdio |
| Tools it declares | Not published | Not published |
| Environment variables it asks for (differs) | 9, secrets among them: 0 | Not published |
| Licence (differs) | Apache-2.0 | Not stated |
| Repository (differs) | github.com/cyanheads/astronomy-mcp-server | github.com/neilberkman/sidereon |
| Changes in the last 7 days | 0 | 0 |
| First seen | 2026-10-11 | 2026-10-11 |
| Endpoint at the last check (differs) | Status out of date: last check 2 days ago returned HTTP 200 | no remote endpoint we check |
Lines where the two differ have a tinted background and bold values. Where the data itself says which value is better (more marketplaces, a larger figure of the same marketplace, a fresher release, a verified mark on a marketplace that lists both), the better one is also marked green with ▲ and the worse one red with ▼. Where it runs, the transport, the tools, the settings, hooks, the bundle's parts, the licence and the week's changes are marked only as different: more or fewer is not better in itself.
What each says it does
io.github.cyanheads/astronomy-mcp-server
Offline observational astronomy: positions, rise/set, moon phases, eclipses, and seasons.
Sidereon
GNSS positioning and astrodynamics: orbit propagation, passes, GNSS solves, and RINEX QC
How to run each
io.github.cyanheads/astronomy-mcp-server As a remote MCP server
claude mcp add --transport http astronomy-mcp-server https://astronomy.caseyjhand.com/mcpSidereon
No data for an automatic command: what its marketplaces declare does not say unambiguously how to connect it.
Commands built only from what the marketplaces declare; the full set for every client is on each card.
Only io.github.cyanheads/astronomy-mcp-server has a remote endpoint we check. How we check endpoints
Tools each declares
Neither the marketplaces of Sidereon nor its endpoint list any tools, so we do not compare tools.
Settings each asks for
The marketplaces of Sidereon publish no settings it asks for, so we do not compare settings.
What it can do: io.github.cyanheads/astronomy-mcp-server · What it can do: Sidereon · Compare two other plugins
Data comes from the Official MCP Registry (registry.modelcontextprotocol.io), CC0 1.0. Package data comes from the public npm registry (registry.npmjs.org). Figures come from our own regular passes over the marketplaces, last read on . We publish no contact details for plugin publishers.