(28978) Ixion
This object has a more recent orbit available here
Object
Object | (28978) Ixion |
Diameter(1) | 617 km |
Dynamic class(1) | plutino |
Absolute magnitude | 3.44 |
G slop | 0.15 |
(1) Data from the johnston archive list.
Orbital elements
Epoch (Julian date) | 2459800.5 |
Semi major axis | 39.664021 ± 0.000175 au |
Eccentricity | 0.247144023 ± 0.000002490 |
Inclination | 19.643362059 ± 0.000014942 ° |
Longitude of ascending node | 71.059914 ± 0.000015 ° |
Argument of perihelia | 299.168262 ± 0.000708 ° |
Mean anomaly | 291.227260 ± 0.000893 ° |
Orbital period | 249.81 yr |
Ephemeris & Observations
Ephemeris version | NIMAv12 |
Observation file |
omc_ast_NIMAv12.txt |
bsp file | 28978_Ixion_nima_v12.bsp |
Date of first observation | 1982-07-17 |
Date of last observation | 2021-04-28 |
Number of observations used in the fit | 447 |
Number of rejected observations | 2 |
Number of DES observations | 0 |
Number of MPC observations | 194 |
Number of unpublished observations | 255 |
RMS of observations | 0.199 arcsec |
Residuals

Residuals in right ascension and declination compared to NIMAv12 ephemeris.
Colours indicate the estimated precision in arcsec used as weights in the fitting process.
Orbit quality
date | σα (arcsec) | σδ (arcsec) |
2022-01 | 0.005 | 0.004 |
2022-07 | 0.007 | 0.005 |
2023-01 | 0.008 | 0.006 |
2023-07 | 0.010 | 0.007 |
2024-01 | 0.012 | 0.008 |
2024-07 | 0.015 | 0.009 |
2025-01 | 0.017 | 0.009 |
2025-07 | 0.021 | 0.011 |
2026-01 | 0.023 | 0.011 |
Ephemeris comparison

Difference between NIMAv12 and JPL18 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.