1373 Cincinnati Discovery [1] Discovered by E. Hubble Discovery site Mount Wilson Obs. Discovery date 30 August 1935 Designations MPC designation (1373) Cincinnati Named after Cincinnati Observatory [1] Alternative designations 1935 QN Minor planet category 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 82.62 yr (30,176 d) Aphelion 4.4958 AU Perihelion 2.3457 AU Semi-major axis 3.4208 AU Eccentricity 0.3143 Orbital period 6.33 yr (2,311 d) Mean anomaly 98.044° Mean motion 0° 9m 20.88s / day Inclination 38.936° Longitude of ascending node 297.47° Argument of perihelion 99.148° TJupiter 2.7190 Physical characteristics Mean diameter 19.448±0.175 km[6][7] 19.751±0.165 km[8] 22.16±1.66 km[9] Rotation period 5.2834±0.0002 h[10] Geometric albedo 0.119[9] 0.1518[8] 0.155[6][7] Spectral type SMASS = Xk [11] M [8] Absolute magnitude (H) 11.20[6][8][9] 11.5[1][2][3]