| Discovery[1] | |
|---|---|
| Discovered by | E. F. Helin |
| Discovery site | Palomar Obs. |
| Discovery date | 11 February 1989 |
| Designations | |
| (5905) Johnson | |
Named after | Lindley N. Johnson (astronomer, engineer)[2] |
| 1989 CJ1 | |
| main-belt · (inner)[1] Hungaria[3][4] · background[5] | |
| Orbital characteristics[1] | |
| Epoch 23 March 2018 (JD 2458200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 28.96 yr (10,576 days) |
| Aphelion | 2.0476AU |
| Perihelion | 1.7727 AU |
| 1.9102 AU | |
| Eccentricity | 0.0720 |
| 2.64yr (964 days) | |
| 174.14° | |
| 0° 22m 23.88s / day | |
| Inclination | 27.521° |
| 141.28° | |
| 208.81° | |
| Knownsatellites | 1(P: 21.78 h; 0.4 Ds/Dp)[6][a] |
| Physical characteristics | |
| 3.62±0.67 km[7] 3.85±0.66 km[8] 4.1±0.5 km[9] 4.728±0.064 km[10] 4.791±0.065 km[11] 4.797 km[12] 4.80 km(taken)[4] | |
| 3.78142±0.0002h[b] 3.78222±0.0001 h[13] 3.7823±0.0002 h[14] 3.7824±0.0001 h[6] 3.7827±0.0002 h[15][c] | |
| 0.1524[12] 0.1939±0.0278[11] 0.198±0.022[10] 0.25±0.10[8] 0.266±0.100[9] 0.44±0.17[7] | |
| S(assumed)[4] | |
| 13.6±0.3(R)[13] · 14.0[1][7][11][15] · 14.00±0.1[9] · 14.15±0.92[16] · 14.21[8] · 14.255±0.13[4][12] | |
5905 Johnson, provisional designation1989 CJ1, is a Hungariaasteroid and synchronousbinary system[a] from the innermost regions of theasteroid belt, approximately 4 kilometers (2.5 miles) in diameter. It was discovered on 11 February 1989, by American astronomerEleanor Helin atPalomar Observatory in California, United States.[3] Itssatellite measures approximately 1.6 km (1 mi) in diameter and orbits its primary every 21.8 hours.[6] It was named after American astronomer and engineerLindley N. Johnson.[2]
Johnson is a stonyS-type asteroid and member of the dynamicalHungaria group, which forms the innermost dense concentration of asteroids in theSolar System.[3][4] It is, however, not a member of collisionalHungaria family, but a non-family asteroid of the main belt'sbackground population when applying thehierarchical clustering method to itsproper orbital elements.[5]
It orbits the Sun in theinner asteroid belt at a distance of 1.8–2.0 AU once every 2 years and 8 months (964 days;semi-major axis of 1.91 AU). Its orbit has aneccentricity of 0.07 and aninclination of 28° with respect to theecliptic.[1] As noprecoveries were taken, and no prior identifications were made, the body'sobservation arc begins at Palomar with its official discovery observation in February 1989.[3]
According to the surveys carried out by NASA's space-basedSpitzer andWISE telescopes, and theNEOWISE mission,Johnson measures between 3.62 and 4.791 kilometers in diameter, and its surface has analbedo between 0.19 and 0.44.[7][8][9][10][11] TheCollaborative Asteroid Lightcurve Link adoptsPetr Pravec's revised WISE-data, that is, an albedo of 0.1524 and a diameter of 4.80 kilometers for an absolute magnitude of 14.255.[4]
Between 1 and 11 April 2005, the first ever rotationallightcurve was obtained from photometric observations taken by astronomersBrian Warner at the Palmer Divide Observatory, Colorado, by Petr Pravec andPeter Kušnirák atOndřejov Observatory, Czech Republic, byAdrián Galád andŠtefan Gajdoš atModra Observatory, Slovakia, and by P. Brown and Z. Krzeminski of the Department of Physics and Astronomy atUWO in Ontario, Canada.[6][a]
These observations revealed, thatJohnson is a synchronousbinary asteroid with amoon orbiting its primary every 21.785 hours. The observed mutualasteroid occultation and eclipsing events had amagnitude of between 0.15 and 0.18 magnitude, suggesting that the satellite's diameter measures40% of that ofJohnson (a secondary-to-primary diameter ratio of 0.4), which translates into amean diameter of 1.4–1.9 kilometer.[6][a]
SinceJohnson's first observation in April 2005, astronomer Brian Warner and Petr Pravec have obtained additional lightcurves.[d][c] They gave a revisedrotation period for the primary of 3.7814 to 3.7824 hours with a brightness variation between 0.10 and 0.20 magnitude (U=3/3/3/3/3). These observations also confirmed thatJohnson is a binary system, giving a concurringorbital period of 21.78 to 21.797 hours for the satellite.[13][14][15][b] For an asteroid of its size,Johnson has a somewhat fast spin rate, but still significantly above those offast rotators. CALL adopts a rotation period of 3.7824 hours with an amplitude of 0.20 magnitude.[4]
Thisminor planet was named after American astronomer and engineer Lindley N. Johnson at NASA'sJet Propulsion Laboratory. A space enthusiast since the age of 12, Johnson has been instrumental for theNear-Earth Asteroid Tracking program, which became operational atGEODSS on Hawaii (Haleakala-NEAT;566) in December 1995.[2] The approved naming citation was published by theMinor Planet Center on 3 May 1996 (M.P.C. 27128).[17]
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