Accuracy
We compare the engine's planetary longitudes with NASA JPL Horizons (DE441), the reference used by professional astronomers, for every body at regular dates across 1900–2025. The differences below are in arc-seconds (″); one degree is 3,600″.
| Body | Median ″ | Max ″ |
|---|---|---|
| Sun | 0.38 | 1.63 |
| Moon | 0.92 | 4.05 |
| Mercury | 1.44 | 9.47 |
| Venus | 1.13 | 13.8 |
| Mars | 1.01 | 9.42 |
| Jupiter | 2.35 | 9.40 |
| Saturn | 2.33 | 11.0 |
| Uranus | 3.18 | 11.6 |
| Neptune | 11.3 | 18.5 |
| Pluto | 1.79 | 3.66 |
These are ephemeris differences only: for dates after 2025 both sides predict ΔT (the Earth's clock drift), and their predictions diverge, which is a model choice rather than an error.
Chart-level checks
Every change to the engine must reproduce all 291 golden charts exactly (lagna, all nine grahas, nakshatras, houses, dashas)
before it can ship. A calculation change that alters any of them is announced in the
changelog with the new engine_version.
Check it yourself
Download the test set (JSON): every date, body, the JPL longitude, our longitude and the difference.