1397 Umtata

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1397 Umtata
Discovery [1]
Discovered by C. Jackson
Discovery site Johannesburg Obs.
Discovery date 9 August 1936
MPC designation (1397) Umtata
Named after
(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)
0° 13m 28.56s / day
Inclination 3.5109°
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]
0.10 (assumed)[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]

Orbit and classification[edit]

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]

Physical characteristics[edit]

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[edit]

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[edit]

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 before November 1977 (M.P.C. 909).[10]


  1. ^ Asteroid Lightcurve Data Base (LCDB) – 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.


  1. ^ a b c d e f "JPL Small-Body Database Browser: 1397 Umtata (1936 PG)" (2017-10-01 last obs.). Jet Propulsion Laboratory. Retrieved 17 October 2017. 
  2. ^ a b c Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (1397) Umtata. Springer Berlin Heidelberg. p. 113. ISBN 978-3-540-00238-3. Retrieved 17 October 2017. 
  3. ^ a b c d e f g h "LCDB Data for (1397) Umtata". Asteroid Lightcurve Database (LCDB). Retrieved 17 October 2017. 
  4. ^ a b "Small Bodies Data Ferret". Nesvorny HCM Asteroid Families V3.0. Retrieved 17 October 2017. 
  5. ^ a b c d Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. Retrieved 17 October 2017. 
  6. ^ a b c Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645Freely accessible. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121. Retrieved 17 October 2017. 
  7. ^ a b c d Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results" (PDF). The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407Freely accessible. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. Retrieved 17 October 2017. 
  8. ^ a b c Binzel, R. P. (October 1987). "A photoelectric survey of 130 asteroids". Icarus: 135–208. Bibcode:1987Icar...72..135B. doi:10.1016/0019-1035(87)90125-4. ISSN 0019-1035. Retrieved 17 October 2017. 
  9. ^ a b "1397 Umtata (1936 PG)". Minor Planet Center. Retrieved 17 October 2017. 
  10. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 17 October 2017. 

External links[edit]