(588) Achilles


Object

Object (588) Achilles
Diameter(1) 130 km
Dynamic class(1) trojan
Absolute magnitude 8.26
G slop 0.15
(1) Data from the johnston archive list.

Orbital elements

Epoch (Julian date) 2456468.249406684
Semi major axis 5.199067 ± 0.000001 au
Eccentricity 0.148169636 ± 0.000000057
Inclination 10.317133259 ± 0.000006667 °
Longitude of ascending node 316.593823 ± 0.000031 °
Argument of perihelia 133.112313 ± 0.000072 °
Mean anomaly 61.516921 ± 0.000046 °
Orbital period 11.85 yr

Ephemeris & Observations

Ephemeris version NIMAv4
Observation file (documentation) omc_ast_NIMAv4.txt
bsp file 588_Achilles_nima_v4.bsp
Date of first observation 1906-02-22
Date of last observation 2020-11-14
Number of observations used in the fit 2368
Number of rejected observations 34
Number of DES observations 0
Number of MPC observations 2354
Number of unpublished observations 48
RMS of observations 4.874 arcsec

Residuals

residual plot

Residuals in right ascension and declination compared to NIMAv4 ephemeris.
Colours indicate the estimated precision in arcsec used as weights in the fitting process.

Orbit quality

date σα (arcsec) σδ (arcsec)
2021-01 0.008 0.009
2021-07 0.019 0.015
2022-01 0.025 0.024
2022-07 0.036 0.023
2023-01 0.060 0.036
2023-07 0.048 0.024
2024-01 0.075 0.042
2024-07 0.049 0.028
2025-01 0.060 0.038

Ephemeris comparison

residual plot

Difference between NIMAv4 and JPL88 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.

Previous NIMA versions