| Minorplanet: | yes |
| 873 Mechthild | |
| Background: |
|
| Discovery Ref: |   |
| Discovered: | 21 May 1917 |
| Mpc Name: | (873) Mechthild |
| Alt Names: | A917 KJ1917 CA |
| Named After: | unknown  |
| Mp Category: |
|
| Orbit Ref: |   |
| Epoch: | 31 May 2020 (JD 2459000.5) |
| Uncertainty: | 0 |
| Observation Arc: | 102.24 yr (37,343 d) |
| Perihelion: | 2.2346 AU |
| Semimajor: | 2.6273 AU |
| Eccentricity: | 0.1495 |
| Period: | 4.26 yr (1,555 d) |
| Mean Motion: | / day |
| Inclination: | 5.2763° |
| Asc Node: | 150.00° |
| Arg Peri: | 109.99° |
| Mean Diameter: | |
| Pole Ecliptic Lat: |
|
| Albedo: | |
| Spectral Type: | |
| Abs Magnitude: | 11.4 |
873 Mechthild (prov. designation: or) is a dark background asteroid from the central regions of the asteroid belt. It was discovered by German astronomer Max Wolf at the Heidelberg Observatory on 21 May 1917. The primitive P-type asteroid has a rotation period of 11.0 hours and measures approximately 34km (21miles) in diameter. The origin of the asteroid's name remains unknown.
Mechthild is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements. It orbits the Sun in the central asteroid belt at a distance of 2.2–3.0 AU once every 4 years and 3 months (1,555 days; semi-major axis of 2.63 AU). Its orbit has an eccentricity of 0.15 and an inclination of 5° with respect to the ecliptic. The body's observation arc begins with its first and official discovery observation at Heidelberg Observatory on 21 May 1917.
This minor planet is named "Mechthild", a German feminine given name. Any reference of this name to a specific person or occurrence is unknown.
Among the many thousands of named minor planets, Mechthild is one of 120 asteroids, for which no official naming citation has been published. All of these low-numbered asteroids have numbers between and and were discovered between 1876 and the 1930s, predominantly by astronomers Auguste Charlois, Johann Palisa, Max Wolf and Karl Reinmuth.
In the Tholen classification, Mechthild is closest to a very dark, primitive P-type, and somewhat similar to a common C-type asteroid. In the taxonomy by Barucci, it is a C0-type. P-type asteroids are more common in the outer asteroid belt and among the Jupiter trojan population.
In May 2015, a rotational lightcurve of Mechthild was obtained from photometric observations by Brian Warner at his Palmer Divide Observatory in Colorado. Lightcurve analysis gave a rotation period of hours with a brightness amplitude of magnitude .
Alternative period determinations were made by Claes-Ingvar Lagerkvist in March 1976, by astronomers at the Palomar Transient Factory in January 2014, and by the Spanish group of asteroid observers, OBAS in May 2015 . In 2016, a modeled lightcurve gave a concurring sidereal period of hours using data from a large collaboration of individual observers (such as above). The study also determined two spin axes of (249.0°, −52.0°) and (51.0°, −61.0°) in ecliptic coordinates (λ, β).
According to the surveys carried out by the Infrared Astronomical Satellite IRAS, and the Japanese Akari satellite, and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), Mechthild measures, and kilometers in diameter and its surface has an albedo of, and, respectively. The Collaborative Asteroid Lightcurve Link adopts the results from IRAS, that is, an albedo of 0.0531 and a diameter of 29.04 kilometers based on an absolute magnitude of 11.49. Alternative mean-diameter measurements published by the WISE team include and with corresponding albedos of and .