1397 Umtata
Main-belt asteroid
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1397 Umtata, provisional designation 1936 PG, is an asteroid from the background population of the asteroid belt's central region, approximately 21 kilometers in diameter. It was discovered by South-African astronomer Cyril Jackson at the Union Observatory in Johannesburg on 9 August 1936.[9] The asteroid was named after the South-African town of Mthatha, formerly known as Umtata.[2]
| Discovery[1] | |
|---|---|
| Discovered by | C. Jackson |
| Discovery site | Johannesburg Obs. |
| Discovery date | 9 August 1936 |
| Designations | |
| (1397) Umtata | |
Named after | Mthatha[2] (South-African town) |
| 1936 PG · 1931 GK 1945 QF · 1945 RC 1948 EB1 | |
| main-belt · (middle)[3] background[4] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 81.14 yr (29,638 days) |
| Aphelion | 3.3646 AU |
| Perihelion | 1.9967 AU |
| 2.6806 AU | |
| Eccentricity | 0.2551 |
| 4.39 yr (1,603 days) | |
| 173.37° | |
| 0° 13m 28.56s / day | |
| Inclination | 3.5109° |
| 77.437° | |
| 206.53° | |
| Physical characteristics | |
| Dimensions | 20.35±0.30 km[5] 20.40 km (derived)[3] 20.798±0.292 km[6] 22.895±0.285 km[7] |
| 30 h[8] | |
| 0.0794±0.0140[7] 0.084±0.046[6] 0.10 (assumed)[3] 0.112±0.004[5] | |
| S/C[3] BâV = 0.690[1] UâB = 0.210[1] | |
| 11.47[1][5] · 11.57[3][7][8] | |
Orbit and classification
Umtata is a non-family asteroid of the main belt's background population.[4] It orbits the Sun in the central asteroid belt at a distance of 2.0â3.4 AU once every 4 years and 5 months (1,603 days). Its orbit has an eccentricity of 0.26 and an inclination of 4° with respect to the ecliptic.[1]
The asteroid was first identified as 1931 GK at the Lowell Observatory in April 1931. The body's observation arc begins with its official discovery observation at Johannesburg.[9]
Physical characteristics
The asteroid's spectral type is unknown. The Lightcurve Data Base assumes an S- or C-type to be equally likely, using an average albedo of 0.10 (see below).[3][a]
Rotation period
In May 1984, a rotational lightcurve of Umtata was obtained from photometric observations by American astronomer Richard Binzel. Analysis of the fragmentary lightcurve gave a rotation period of 30 hours with a brightness amplitude of 0.13 magnitude (U=1).[8] As of 2017, no secure period has been obtained.[3]
Diameter and albedo
According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Umtata measures between 20.35 and 22.895 kilometers in diameter and its surface has an albedo between 0.0794 and 0.112.[5][6][7]
The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.10 â a compromise value between the stony (0.20) and carbonaceous asteroid's, both abundant in the main belt's central region â and derives a diameter of 20.40 kilometers based on an absolute magnitude of 11.57.[3]
Naming
This minor planet was named after South-African town of Mthatha, formerly known as Umtata. It is the capital town of the OR Tambo District Municipality and the King Sabata Dalindyebo Local Municipality.[2] The official naming citation was published by the Minor Planet Center in April 1953 (M.P.C. 909).[10]
Notes
- Asteroid Lightcurve Data Base (LCDB) â 2. Taxonomic Class, orbital class, and albedo. The LCDB generically assumes a S/C-type with an albedo of 0.10 for non-family main belt asteroids with a semi-major axis between 2.6 and 2.7.
