(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 ± 0.000001 au |
Eccentricity | 0.041745069 ± 0.000000158 |
Inclination | 9.375666799 ± 0.000012310 ° |
Longitude of ascending node | 312.410154 ± 0.000072 ° |
Argument of perihelia | 48.702170 ± 0.000403 ° |
Mean anomaly | 305.976080 ± 0.000388 ° |
Orbital period | 14.76 yr |
Ephemeris & Observations
Ephemeris version | NIMAv2 |
Observation file |
omc_ast_NIMAv2.txt |
bsp file | 29P_Schwassmann-Wachmann_nima_v2.bsp |
Date of first observation | 2009-02-17 |
Date of last observation | 2020-11-19 |
Number of observations used in the fit | 559 |
Number of rejected observations | 0 |
Number of DES observations | 0 |
Number of MPC observations | 0 |
Number of unpublished observations | 559 |
RMS of observations | 0.079 arcsec |
Residuals

Residuals in right ascension and declination compared to NIMAv2 ephemeris.
Colours indicate the estimated precision in arcsec used as weights in the fitting process.
Orbit quality
date | σα (arcsec) | σδ (arcsec) |
2022-01 | 0.149 | 0.053 |
2022-07 | 0.145 | 0.041 |
2023-01 | 0.232 | 0.068 |
2023-07 | 0.189 | 0.068 |
2024-01 | 0.290 | 0.133 |
2024-07 | 0.229 | 0.111 |
2025-01 | 0.325 | 0.187 |
2025-07 | 0.268 | 0.153 |
2026-01 | 0.350 | 0.206 |
Ephemeris comparison

Difference between NIMAv2 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.