| Discovery[1] | |
|---|---|
| Discovered by | P. Wild |
| Discovery site | Zimmerwald Obs. |
| Discovery date | 17 April 1968 |
| Designations | |
| (1831) Nicholson | |
Named after | Seth B. Nicholson[2] (American astronomer) |
| 1968 HC · 1948 GF 1955 ML | |
| main-belt[1][3] · (inner) Baptistina[4] · Flora[4][5] | |
| Orbital characteristics[3] | |
| Epoch 27 April 2019 (JD 2458600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 62.92yr (22,982 d) |
| Aphelion | 2.5257AU |
| Perihelion | 1.9527 AU |
| 2.2392 AU | |
| Eccentricity | 0.1279 |
| 3.35 yr (1,224 d) | |
| 36.790° | |
| 0° 17m 38.76s / day | |
| Inclination | 5.6335° |
| 72.604° | |
| 183.46° | |
| Physical characteristics | |
| 7.10±1.29 km[6] 8.08±0.47 km[7][8] | |
| 3.228±0.001 h[9] | |
| 0.296[8][7] 0.39[6] | |
| SMASS =S[3][5] | |
| 12.40[7][8] 12.5[1][3][5] 12.70[6] | |
1831 Nicholson, provisional designation1968 HC, is a stonyasteroid of theBaptistina family from the inner regions of theasteroid belt, approximately 8 kilometers (5 miles) in diameter. It was discovered on 17 April 1968, by Swiss astronomerPaul Wild at theZimmerwald Observatory near Bern, Switzerland.[1] TheS-type asteroid has arotation period of 3.2 hours. It was named for American astronomerSeth B. Nicholson.[2]
According to aHCM-analysis byDavid Nesvorný,Nicholson is a member of theBaptistina family (403),[4] located within the greaterFlora family a giantasteroid clan and the largestfamily of stony asteroids in the asteroid belt.[5][4][10] Conversely, and since the existence of a proper Flora family has been ruled out by other astronomers,Nicholson has also been classified as abackground asteroid.[11]
It orbits the Sun in theinner main-belt at a distance of 2.0–2.5 AU once every 3 years and 4 months (1,224 days;semi-major axis of 2.24 AU). Its orbit has aneccentricity of 0.13 and aninclination of 6° with respect to theecliptic.[3] The asteroid was first observed as1948 GF at theNice Observatory in April 1948. The body'sobservation arc begins with its observation as1955 ML at theGoethe Link Observatory in June 1955, almost 13 years prior to its official discovery observation atZimmerwald.[1]
Thisminor planet was named by the discoverer in memory of American astronomerSeth B. Nicholson (1891–1963), who pioneered in several branches of planetary research atMount Wilson Observatory and who discovered four ofJupiter's numerous moons – namely,Sinope,Lysithea,Carme, andAnanke. The lunar craterNicholson and the dark terrain ofNicholson Regio on Jupiter's moonGanymede, as well as the impact craterNicholson on Mars have also been named after him.[2] The officialnaming citation was published by theMinor Planet Center on 15 October 1977 (M.P.C. 4236).[12]
In theSMASS classification,Nicholson is a common stonyS-type asteroid.[3][5]
In April 2015, a rotationallightcurve ofNicholson was obtained fromphotometric observations by a group of Spanish astronomers from Valencia and Alicante at various observatories: (J08), (Z95), (J67), (Z98) and (I57). Lightcurve analysis gave a well-definedrotation period of3.228±0.001 hours and a brightness variation of 0.24magnitude (U=3).[9] At the same time, Serbian astronomer Vladimir Benishek at theBelgrade Observatory determined a concurring period of3.25510±0.00003 hours with an amplitude of 0.29 magnitude (U=3).[13]
According to the survey carried out by theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer,Nicholson measures 7.1 and 8.1 kilometers in diameter and its surface has analbedo of 0.39 and 0.296, respectively.[6][7][8] TheCollaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – derived from8 Flora, the namesake of the Flora family – and calculates a diameter of 8.58 kilometers based on anabsolute magnitude of 12.5.[5]
