_Tombaugh.png) Shape model ofTombaugh from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | C. O. Lampland |
| Discovery site | Lowell Obs. |
| Discovery date | 24 March 1931 |
| Designations | |
| (1604) Tombaugh | |
Named after | Clyde Tombaugh (astronomer)[2] |
| 1931 FH · 1930 DX 1933 SA1 · 1936 FA 1937 JH · 1941 CF 1943 OE · 1948 ME 1949 ST1 · A920 EC | |
| main-belt · Eos[3] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 96.51 yr (35,252 days) |
| Aphelion | 3.3309AU |
| Perihelion | 2.7161 AU |
| 3.0235 AU | |
| Eccentricity | 0.1017 |
| 5.26yr (1,920 days) | |
| 359.39° | |
| 0° 11m 15s / day | |
| Inclination | 9.3941° |
| 309.10° | |
| 38.199° | |
| Physical characteristics | |
| Dimensions | 28.78±0.53 km[4] 32.25 km(derived)[3] 32.33±2.2 km(IRAS:3)[5] |
| 6.15h(dated)[6] 7.04 h(dated)[7] 7.047±0.004 h[8] 7.056±0.001 h[9] 8.2 h(dated)[10] | |
| 0.0933(derived)[3] 0.1038±0.016(IRAS:3)[5] 0.138±0.006[4] | |
| B–V = 0.751[1] U–B = 0.373[1] XSCU(Tholen)[1] · Xc(SMASS)[1] · X[3] | |
| 10.4[1] · 10.53[5][4] · 10.65[3][7] · 10.93±0.15[11] | |
1604 Tombaugh, provisional designation1931 FH, is a rare-typeEos asteroid from the outer region of theasteroid belt, approximately 32 kilometers in diameter. It was discovered on 24 March 1931, by American astronomerCarl Otto Lampland atLowell Observatory in Flagstaff, Arizona, in the United States.[12] It was named after the discoverer of Pluto,Clyde Tombaugh.[2]
Tombaugh is a member of theEos family that orbits the Sun in theouter main-belt at a distance of 2.7–3.3 AU once every 5 years and 3 months (1,920 days). Its orbit has aneccentricity of 0.10 and aninclination of 9° with respect to theecliptic.[1] Itsobservation arc begins at Flagstaff, one year prior to its official discovery observation at Lowell Observatory. It had been previously identified atHeidelberg asA920 EC in 1920, and as1930 DX in 1930.[12]
Tombaugh is classified as anX-type asteroid. It is also classified as a rare XSCU type in theTholen, and as a transitional Xc type in theSMASS taxonomy.[1]
In April 2010 and November 2012, rotationallightcurves ofTombaugh were obtained from photometric observations at Oakley Southern Sky Observatory, Australia, and atBassano Bresciano Observatory, Italy. Lightcurve analysis gave arotation period of 7.047 and 7.056 hours with a brightness variation of 0.16 and 0.35magnitude, respectively (U=2+/2+).[8][9]
These periods supersede previous results obtained by astronomersClaes-Ingvar Lagerkvist (1975),Richard P. Binzel (1984) andKrisztián Sárneczky (U=1/2/2).[6][7][10]
According to the surveys carried out by the Infrared Astronomical SatelliteIRAS and the JapaneseAkari satellite,Tombaugh measures 28.78 and 32.33 kilometers in diameter, and its surface has analbedo of 0.138 and 0.104, respectively.[4][5] TheCollaborative Asteroid Lightcurve Link derives an albedo of 0.0933 and a diameter of 32.25 kilometers with anabsolute magnitude of 10.65.[3]
Thisminor planet was named for American astronomerClyde Tombaugh (1906–1997), famous for his discovery ofPluto in 1930. The discovering Lowell Observatory named this asteroid on the occasion of a symposium on Pluto, held in 1980. When Tombaugh examined the photographic plates during the trans-Saturnian search program at the Lowell Observatory, he also marked over 4,000 minor planets on these plates.[2] The approved naming citation was published by theMinor Planet Center on 1 April 1980 (M.P.C. 5280).[13]
