What does a real call return?
For the Moon over Paris on 30 September 2026 at 23:00 UTC, the engine computed azimuth 91.4° and elevation 35.8°. The claimed position is 12.4° away, beyond the allowed 2.3°, so the verdict is contredit (contradicted).
Recorded on 2 November 2026 through the public MCP endpoint, service release 0.17.1. Inputs and full responses, response SHA-256 13aeab224060…. Verdict values are the literal values the tool returns. Run the same inputs yourself to compare; elapsed times vary, and a new release may change the figures.
Checked against
- Meeus sidereal-time and lunar-position examples, lunar phase and geometric topocentric parallax limiting cases.
- Shared 37-sample Skyfield/DE421 solar comparison and a native claimed-direction versus mirrored-direction regression.
Recorded on release 0.16.1. These checks cover the listed cases, not every input. Evidence cards.
How it works
The engine calculates solar and lunar coordinates and compares the claimed azimuth and elevation using angular separation. Lunar coordinates include an observer correction on WGS84 at sea level; atmospheric refraction uses a standard model.
Inputs and units
Supply date, latitude, longitude, object, claimed azimuth and elevation, and tolerance in degrees. The object codes in the current tool schema are soleil and lune.
What the result contains
Calculated positions, angular separation, adopted tolerance, lunar phase and a conditional compatibility result support a transparent check of a specific claim.
Example MCP call
{
"name": "check_ephemeris",
"arguments": {
"date_utc": "2026-09-30T23:00:00Z",
"latitude": 48.85,
"longitude": 2.35,
"object": "lune",
"claimed_azimuth_deg": 81,
"claimed_elevation_deg": 27.1,
"tolerance_deg": 2
}
}Send this tool name and arguments through a connected MCP client. Discover the authoritative input schema with tools/list.
Call this engine in one command
Node.js 20+ and npm. This downloads a small remote MCP client; it does not install the engine locally.
npx --yes --package https://scorecompute.com/downloads/scorecompute-call-0.14.2.tgz scorecompute-call check_ephemeris --arguments '{"date_utc":"2026-09-30T23:00:00Z","latitude":48.85,"longitude":2.35,"object":"lune","claimed_azimuth_deg":81,"claimed_elevation_deg":27.1,"tolerance_deg":2}'Client download, PowerShell input and verification →
Cite this engine
Engine identified by source hash, source SHA-256 102dee0aac2c…. Evidence recorded on release 0.16.1; the public service currently runs 0.17.1. Replace the access date when you cite it.
ScoreCompute. Sun and Moon position consistency (check_ephemeris), identified by source hash, source SHA-256 102dee0aac2c8bcbf21c1367719376bda7b59f41912a6a5f21d92095ded16e3a. Evidence release 0.16.1, service release 0.17.1. https://scorecompute.com/engines/check-ephemeris/ (accessed YYYY-MM-DD).
All engine citations · Evidence card
Execution and availability
ScoreCompute exposes this tool through MCP Streamable HTTP. Rust computation runs on a connected worker; the public website and MCP gateway run separately. Among these 22 scientific tools, CUDA is implemented for simulate_pi; the other scientific engines run on CPU. The separate contributor network runs two compiled public workloads: a π estimate and fixed synthetic schedule probes. Requests are bounded and concurrent work may be refused when capacity is occupied.
Record inputs, assumptions and returned provenance when sharing a result. The public observatory displays software client names and tool activity, without publishing calculation arguments or results.