(588) Achilles
This object has a more recent orbit available here
Object
Object | (588) Achilles |
Diameter(1) | 130 km |
Dynamic class(1) | trojan |
Absolute magnitude | 8.32 |
G slop | 0.15 |
(1) Data from the johnston archive list.
Orbital elements
Epoch (Julian date) | 2460600.5 |
Semi major axis | 5.212198 ± 0.000000 au |
Eccentricity | 0.148450053 ± 0.000000041 |
Inclination | 10.317503932 ± 0.000003969 ° |
Longitude of ascending node | 316.539333 ± 0.000018 ° |
Argument of perihelia | 133.984316 ± 0.000027 ° |
Mean anomaly | 43.908675 ± 0.000016 ° |
Orbital period | 11.90 yr |
Ephemeris & Observations
Ephemeris version | NIMAv8 |
Observation file |
omc_ast_NIMAv8.txt |
bsp file | 588_Achilles_nima_v8.bsp |
Date of first observation | 1906-02-22 |
Date of last observation | 2024-06-06 |
Number of observations used in the fit | 4343 |
Number of rejected observations | 44 |
Number of DES observations | 0 |
Number of MPC observations | 4323 |
Number of unpublished observations | 64 |
RMS of observations | 3.604 arcsec |
Residuals

Residuals in right ascension and declination compared to NIMAv8 ephemeris.
Colours indicate the estimated precision in arcsec used as weights in the fitting process.
Orbit quality
date | σα (arcsec) | σδ (arcsec) |
2024-01 | 0.030 | 0.021 |
2024-07 | 0.022 | 0.014 |
2025-01 | 0.032 | 0.021 |
2025-07 | 0.027 | 0.018 |
2026-01 | 0.034 | 0.019 |
2026-07 | 0.034 | 0.021 |
2027-01 | 0.035 | 0.016 |
2027-07 | 0.041 | 0.021 |
2028-01 | 0.034 | 0.015 |
Ephemeris comparison

Difference between NIMAv8 and JPL109 in right ascension (weighted by cos δ) and in declination.
Gray area represents the 1-σ uncertainty of NIMA ephemeris. Green dots represent the DES observations.