| Minorplanet: | yes |
| Background: |
|
| 551 Ortrud | |
| Mpc Name: | (551) Ortrud |
| Pronounced: | pronounced as /de/[1] |
| Alt Names: | 1904 PM |
| Discovered: | 16 November 1904 |
| Epoch: | 31 July 2016 (JD 2457600.5) |
| Eccentricity: | 0.12311 |
| Semimajor: | 2.9672AU |
| Perihelion: | 2.6019AU |
| Aphelion: | 3.3325abbr=onNaNabbr=on |
| Period: | 5.11 yr (1866.9 d) |
| Inclination: | 0.39727° |
| Asc Node: | 6.0272° |
| Arg Peri: | 68.010° |
| Mean Motion: | / day |
| Orbit Ref: | [2] |
| Observation Arc: | 111.06 yr (40565 d) |
| Uncertainty: | 0 |
| Abs Magnitude: | 9.57 |
| Rotation: | 13.05abbr=onNaNabbr=on |
| Mean Radius: | km |
551 Ortrud is a minor planet orbiting the Sun. It is located in the Main Belt. In light of the practice of the discover c. 1904 to name his asteroids after female characters in opera, it is likely that Ortrud is named after a character in Richard Wagner's opera Lohengrin.