More astronomical data, with traceable calculations
Longitude, latitude and geocentric distance for 19 bodies use JPL Horizons with a shared time standard.
Coverage: 1900–2100. Civil UT, dynamical TT and Earth-rotation UT1 are separate. Future leap seconds are unknown, and estimated time corrections are labelled.
Interpolation-table verification
808 instants per body: 15,352 comparisons. Eight-point interpolation was compared with separately requested JPL values, including off-grid times and range boundaries. The table shows the largest sampled differences.
| Body | Table step (days) | Longitude (arcsec) | Latitude (arcsec) | Distance (km) | Model |
|---|---|---|---|---|---|
| Sun | 2.5 | 0.0058 | 0.0008 | 0.9936 | DE441 |
| Mercury | 1 | 0.0135 | 0.0221 | 0.1302 | DE441 |
| Venus | 2.5 | 0.0229 | 0.0270 | 1.0251 | DE441 |
| Mars | 2.5 | 0.0223 | 0.0106 | 1.0482 | mar099 |
| Jupiter | 0.5 | 0.7663 | 0.1122 | 1.0125 | jup365_merged |
| Saturn | 2.5 | 0.3659 | 0.1499 | 5.2474 | sat441l |
| Uranus | 2 | 0.3422 | 0.1612 | 8.6733 | ura184_merged |
| Neptune | 1.25 | 0.0508 | 0.0552 | 0.5736 | nep098_merged |
| Pluto | 1.25 | 0.0450 | 0.0126 | 8.2812 | plu060_merged |
| Moon | 1 | 0.0342 | 0.0237 | 0.0249 | DE441 |
| Chiron | 2.5 | 0.0564 | 0.0795 | 2.0161 | JPL#171 |
| Ceres | 2 | 0.0015 | 0.0016 | 0.3149 | JPL#48 |
| Pallas | 2.5 | 0.0207 | 0.0298 | 1.0583 | JPL#74 |
| Juno | 2 | 0.0035 | 0.0039 | 0.3602 | JPL#144 |
| Vesta | 2.5 | 0.2149 | 0.0957 | 1.1490 | JPL#36 |
| Eris | 2.5 | 0.0043 | 0.0008 | 5.1458 | JPL#103 |
| Sedna | 2.5 | 0.0042 | 0.0008 | 5.2422 | JPL#51 |
| Haumea | 2.5 | 0.0046 | 0.0029 | 1.7450 | JPL#132 |
| Makemake | 2.5 | 0.0046 | 0.0008 | 2.8773 | JPL#130 |
These are sampled interpolation differences, not a guarantee of physical accuracy or predictive validity, nor a bound proven for every instant. Orbit models, time corrections and birth-time uncertainty contribute separate errors.
Conventions and scope
- Apparent geocentric ecliptic of date (IAU76/80). Angles in degrees; distance in AU and km.
- Speed is a centered tropical-longitude difference (±28.8 minutes); retrograde flags use the same speed.
- Civil input is UTC since 1962, and UT1 earlier following Horizons. UTC→TAI uses USNO; Earth rotation uses Horizons EOP, with a ΔT model outside the snapshot.
- House calculations retain the four-term nutation approximation. Nodes, Lilith, new moons and eclipse searches use separate calculations; the verification above does not establish their accuracy.
- The standard 130-star list can optionally be extended by 378 stars to 508. Proper motion, precession and nutation are included; annual aberration, parallax and radial-velocity perspective effects are not.
- The four additional bodies are optional references, outside existing interpretations and aspect rules.
Data and reproducibility
Built: 2026-09-10 · 20260910-precision-1
Gzip size (major / small bodies): 3.11 / 1.65 MiB
Major-body verification data · Small-body verification data
Table sampling and display intervals are distinct: intermediate times are interpolated. Rebuild with tools/ephem/build_precision.cjs and build_stars_extra.cjs.
Primary sources: JPL Horizons API · Horizons manual · USNO TAI−UTC · CDS SIMBAD