(29P) Schwassmann-Wachmann
This object has a more recent orbit available here
Object
Object | (29P) Schwassmann-Wachmann |
Diameter(1) | 60 km |
Dynamic class(1) | comet |
Absolute magnitude | 5.85 |
G slop | 0.20 |
(1) Data from the johnston archive list.
Orbital elements
Epoch (Julian date) | 2457754.5 |
Semi major axis | 6.016546 ± 0.000000 au |
Eccentricity | 0.041745067 ± 0.000000102 |
Inclination | 9.375664105 ± 0.000006545 ° |
Longitude of ascending node | 312.410135 ± 0.000028 ° |
Argument of perihelia | 48.702193 ± 0.000113 ° |
Mean anomaly | 305.976075 ± 0.000110 ° |
Orbital period | 14.76 yr |
Ephemeris & Observations
Ephemeris version | NIMAv4 |
Observation file |
omc_ast_NIMAv4.txt |
bsp file | 29P_Schwassmann-Wachmann_nima_v4.bsp |
Date of first observation | 2009-02-17 |
Date of last observation | 2022-12-19 |
Number of observations used in the fit | 1185 |
Number of rejected observations | 0 |
Number of DES observations | 0 |
Number of MPC observations | 0 |
Number of unpublished observations | 1185 |
RMS of observations | 0.079 arcsec |
Residuals

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) |
2022-01 | 0.022 | 0.014 |
2022-07 | 0.008 | 0.005 |
2023-01 | 0.001 | 0.001 |
2023-07 | 0.008 | 0.006 |
2024-01 | 0.026 | 0.017 |
2024-07 | 0.025 | 0.018 |
2025-01 | 0.050 | 0.035 |
2025-07 | 0.044 | 0.031 |
2026-01 | 0.070 | 0.047 |
Ephemeris comparison

Difference between NIMAv4 and JPLK192-43 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.