| Discovery[1] | |
|---|---|
| Discovered by | K. Reinmuth |
| Discovery site | Heidelberg Obs. |
| Discovery date | 22 September 1919 |
| Designations | |
| (2623) Zech | |
Named after | Gert Zech (ARI astronomer)[2] |
| A919 SA · 1963 RE | |
| main-belt · (inner)[3] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 97.70 yr (35,684 days) |
| Aphelion | 2.7846AU |
| Perihelion | 1.7243 AU |
| 2.2545 AU | |
| Eccentricity | 0.2352 |
| 3.39yr (1,236 days) | |
| 324.18° | |
| 0° 17m 28.32s / day | |
| Inclination | 4.0548° |
| 349.11° | |
| 22.883° | |
| Knownsatellites | 1[3][4][5] |
| Physical characteristics | |
| Dimensions | 6.50 km(calculated)[3] 7.61 km(estimate)[5] |
| 2.7401±0.0002h[4] | |
| 0.20(assumed)[3] | |
| S[3][6] | |
| 13.13±0.59[6] · 13.3[1][3] | |
2623 Zech, provisional designationA919 SA, is a stonybinary[4]asteroid from the inner regions of theasteroid belt, approximately 6.5 kilometers in diameter. It was discovered on 22 September 1919, by German astronomerKarl Reinmuth atHeidelberg Observatory in southwest Germany.[7] It was named after GermanARI astronomerGert Zech.[2]
Zech is a stonyS-type asteroid that orbits the Sun in theinner main-belt at a distance of 1.7–2.8 AU once every 3 years and 5 months (1,236 days). Its orbit has aneccentricity of 0.24 and aninclination of 4° with respect to theecliptic.[1] The body'sobservation arc begins with its official discovery observation, as noprecoveries were taken, and no prior identifications were made.[7] On 8 June 2002,Zech passed 0.036 AU (5,400,000 km) from the major asteroid3 Juno.[1]
While "Johnston's Archive" estimates a diameter of 7.61 kilometers forZech,[5] theCollaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 6.5 kilometers based on anabsolute magnitude of 13.3.[3] No observational results have been published by the space-basedIRAS,Akari, andWISE/NEOWISE surveys.[1][3]
In October 2004, a rotationallightcurve ofZech was obtained from photometric observations by American astronomerDonald P. Pray at Sugarloaf Mountain Observatory, Massachusetts, in a collaboration with other American and European astronomers from France, the Czech Republic, Serbia, Georgia and Ukraine. Lightcurve analysis gave arotation period of 2.7401 hours with a brightness variation of 0.22magnitude (U=n.a.).[4] While not being afast rotator, it has a relatively fast spin rate for its size, as most minor planets rotate between 2.2 and 20 hours.
During Pray's photometric observations, it was revealed thatZech (primary) is in fact an asynchronousbinary asteroid with aminor planet moon orbiting it. The moon has anorbital period of 117.2 hours and a spin rate of 18.718 hours with an amplitude 0.08 magnitude.[4] Based on Pray's secondary-to-primary mean diameter ratio (Ds/p) of more than 0.29, theJohnston's Archive estimates a diameter of at least 2.21 kilometers forZech's companion.[5]
Thisminor planet was named after German astronomer Gert Zech (born 1941) atARI in Heidelberg. He was editor ofAstronomy and Astrophysics Abstracts and is known for his publications on the observational determination of the length of theastronomical unit and the mass of theEarth–Moon system using the dynamical method by observing the near-Earth object433 Eros. Naming citation was prepared byLutz D. Schmadel who also proposed the name.[2] The citation was published on 18 February 1992 (M.P.C. 19692).[8]
