index

Performance Benchmarks

Computation performance

Measured on Node 22, Apple M2. Input: 100 observer+date combinations.

Operation	Time
visibility() — Yallop criterion	~2.8 ms/call
visibility() — Odeh criterion	~2.8 ms/call
visibility() — changing observer only	~2.8 ms/call
Batch of 30 consecutive nights	~84 ms total

The dominant cost is the JPL DE442S ephemeris evaluation (Chebyshev polynomial interpolation). The criterion evaluation (Yallop or Odeh) is negligible by comparison. Switching between criteria has no measurable effect on timing.

For UI use cases, a single call is fast enough to run synchronously. For batch processing (scanning many nights or many locations simultaneously), consider Promise.all across concurrent calls or a Worker thread.

Bundle size

Module	Min+gz
moon-sighting (published package)	~14 KB
DE442S kernel	~31 MB (downloaded separately, not in npm package)

The ephemeris kernel is a binary file that users download at runtime (or self-host). It is not bundled in the npm package. See the Getting Started page for setup.

Reproducing the benchmarks

import { visibility } from 'moon-sighting';

const observer = { lat: 21.39, lng: 39.86, elevation: 277 };
const baseDate = new Date(2023, 0, 1);

const dates = Array.from({ length: 100 }, (_, i) => {
  const d = new Date(baseDate);
  d.setDate(d.getDate() + i);
  return d;
});

const start = performance.now();
for (const date of dates) {
  visibility({ ...observer, date });
}
const elapsed = performance.now() - start;

console.log(`${(elapsed / dates.length).toFixed(1)} ms/call`);
console.log(`${elapsed.toFixed(0)} ms total for ${dates.length} calls`);

Run with node --version >= 20 after placing the DE442S kernel file in the working directory.