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] B–V = 0.690 [1] U–B = 0.210 [1] | |
11.47 [1] [5] · 11.57 [3] [7] [8] | |
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]
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 2.0–3.4 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]
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]
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]
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 – a compromise value between the stony (0.20) and carbonaceous asteroid's, both abundant in the main belt's central region – and derives a diameter of 20.40 kilometers based on an absolute magnitude of 11.57. [3]
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]