| Minorplanet: | yes |
| Background: |
|
| 818 Kapteynia | |
| Mpc Name: | (818) Kapteynia |
| Alt Names: | 1916 YZ |
| Discovered: | 21 February 1916 |
| Epoch: | 31 July 2016 (JD 2457600.5) |
| Eccentricity: | 0.094677 |
| Semimajor: | 3.1694AU |
| Perihelion: | 2.8693AU |
| Aphelion: | 3.4695abbr=onNaNabbr=on |
| Period: | 5.64 yr (2060.9 d) |
| Inclination: | 15.664° |
| Asc Node: | 70.816° |
| Arg Peri: | 293.096° |
| Mean Motion: | / day |
| Orbit Ref: | [1] |
| Observation Arc: | 99.92 yr (36496 d) |
| Uncertainty: | 0 |
| Abs Magnitude: | 9.3 |
| Rotation: | 16.35abbr=onNaNabbr=on |
| Moid: | 1.91242AU |
| Jupiter Moid: | 2.0269AU |
| Tisserand: | 3.138 |
818 Kapteynia is a minor planet orbiting the Sun. This asteroid is named for the Dutch astronomer Jacobus Kapteyn.