| Discovery[1] | |
|---|---|
| Discovered by | E. Hubble |
| Discovery site | Mount Wilson Obs. |
| Discovery date | 30 August 1935 |
| Designations | |
| (1373) Cincinnati | |
Named after | Cincinnati Observatory[1] |
| 1935 QN | |
| main-belt[1] · (outer)[2][3] Cybele[4] · ACO[5] | |
| Orbital characteristics[2] | |
| Epoch 27 April 2019 (JD 2458600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 82.62yr (30,176 d) |
| Aphelion | 4.4958AU |
| Perihelion | 2.3457 AU |
| 3.4208 AU | |
| Eccentricity | 0.3143 |
| 6.33 yr (2,311 d) | |
| 98.044° | |
| 0° 9m 20.88s / day | |
| Inclination | 38.936° |
| 297.47° | |
| 99.148° | |
| TJupiter | 2.7190 |
| Physical characteristics | |
| 19.448±0.175 km[6][7] 19.751±0.165 km[8] 22.16±1.66 km[9] | |
| 5.2834±0.0002 h[10] | |
| 0.119[9] 0.1518[8] 0.155[6][7] | |
| SMASS =Xk[11] M[8] | |
| 11.20[6][8][9] 11.5[1][2][3] | |
1373 Cincinnati, provisional designation1935 QN, is anasteroid in a comet-like orbit from theCybele region,[12] located at the outermost rim of theasteroid belt, approximately 20 kilometers (12 miles) in diameter. It was theonly asteroid discovery made by famous American astronomerEdwin Hubble, while observing distant galaxies atMount Wilson Observatory in California on 30 August 1935.[1] The rather sphericalX-type asteroid has arotation period of 5.3 hours.[3] It was named for theCincinnati Observatory.[1]
Cincinnati orbits the Sun in theoutermost asteroid belt at a distance of 2.3–4.5 AU once every 6 years and 4 months (2,311 days;semi-major axis of 3.42 AU). Its orbit has aneccentricity of 0.31 and aninclination of 39° with respect to theecliptic.[2] The body'sobservation arc begins with its official discovery observation atMount Wilson in August 1935.[1]
Cincinnati, a non-family asteroid of the main belt'sbackground population,[13] is located in the orbital region of theCybele asteroids, the last outpost of an extended asteroid belt beyond theHecuba-gap asteroids. Due to its high inclination, and contrary to all other Cybele asteroids,Cincinnati is the only one that is above the center of the ν6secular resonance with Saturn.[4]: 2 The asteroid's high inclination and eccentricity also results in aTisserand's parameter (TJupiter) of 2.719, which makes it a true asteroid in cometary orbit (ACO) for having a TJupiter value below 3.[5]
Recommended by theMinor Planet Center, thisminor planet was named after theCincinnati Observatory, whose staff provided most of the orbit computations. The officialnaming citation was published by theMinor Planet Center on 31 January 1962 (M.P.C. 2116).[14]
In theSMASS classification,Cincinnati is a Xk-type, a subtype that transitions from theX-type to the uncommonK-type asteroids,[11] while theWide-field Infrared Survey Explorer classifies it as a metallicM-type asteroid.[3][8] By 2014,Cincinnati is the only of three Cybele asteroids for which aspectral type has been determined; the other two are522 Helga and692 Hippodamia, an X- andS-type, respectively.[4]: 3
In January 2018, a rotationallightcurve ofCincinnati was obtained fromphotometric observations by Henk de Groot.[10] Lightcurve analysis gave arotation period of5.2834±0.0002 hours and a brightness variation of 0.10magnitude (U=2+).[10] The low brightness amplitude is indicative that is asteroid is rather spherical than elongated in shape.
Alternative period determinations were made by French amateur astronomerRené Roy (5.274 h; Δ0.21 mag) in August 2004 (U=2).[10] Two more lightcurves were obtained byBrian Warner at thisPalmer Divide Observatory in Colorado, United States, in August 2004 and August 2010, who measured a period of 4.930 and 5.28 hours with an amplitude of 0.11 and 0.14 magnitude, respectively.[15][16][a]
According to the survey carried out by theNEOWISE mission of NASA's WISE telescope,Cincinnati measures between 19.4 and 19.8 kilometers in diameter and its surface has analbedo of 0.15–0.16,[6][7][8] while the JapaneseAkari satellite determined a diameter of 22.16 kilometers with an albedo of 0.12.[9] TheCollaborative Asteroid Lightcurve Link assumes a standard albedo for acarbonaceous asteroid of 0.057 and calculates a diameter of 27.9 kilometers based on anabsolute magnitude of 11.5.[3]
