1429 Pemba

1429 Pemba, provisional designation 1937 NH, is a stony background asteroid from the central regions of the asteroid belt, approximately 10 kilometers in diameter. It was discovered on 2 July 1937, by South African astronomer Cyril Jackson at the Union Observatory in Johannesburg.^[11] The asteroid was named for the Pemba Island off the coast of Tanzania.^[2]

1429 Pemba

Discovery[1]
Discovered by	C. Jackson
Discovery site	Johannesburg Obs.
Discovery date	2 July 1937
Designations
MPC designation	(1429) Pemba
Named after	Pemba Island[2] (African East coast)
Alternative designations	1937 NH · 1949 JK
Minor planet category	main-belt · (inner)[3] background[4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	79.93 yr (29,193 days)
Aphelion	3.4109 AU
Perihelion	1.7004 AU
Semi-major axis	2.5557 AU
Eccentricity	0.3347
Orbital period (sidereal)	4.09 yr (1,492 days)
Mean anomaly	207.67°
Mean motion	0° 14m 28.32s / day
Inclination	7.7492°
Longitude of ascending node	47.700°
Argument of perihelion	297.82°
Physical characteristics
Dimensions	8.71±1.86 km[5] 9.874±0.051 km[6] 10.37 km (taken)[3] 10.371 km[7] 10.531±0.041 km[8] 10.75±0.67 km[9]
Synodic rotation period	20 h[10]
Geometric albedo	0.1316[3][7] 0.154±0.021[9] 0.1598±0.0235[8] 0.19±0.11[5] 0.196±0.022[6]
Spectral type	S (assumed)[3]
Absolute magnitude (H)	12.4[1] · 12.50[8][9] · 12.74[3][5] · 12.74±0.2[7][10]

Orbit and classification

Pemba is a non-family asteroid from the main belt's background population.^[4] It orbits the Sun in the central main-belt at a distance of 1.7–3.4 AU once every 4 years and 1 month (1,492 days). Its orbit has an eccentricity of 0.33 and an inclination of 8° with respect to the ecliptic.^[1] The body's observation arc begins with its official discovery observation at Johannesburg.^[11]

Physical characteristics

Pemba is an assumed stony S-type asteroid.^[3]

Rotation period

In September 1982, a rotational lightcurve of Pemba was obtained from photometric observations. Analysis of the fragmentary lightcurve gave a rotation period of 20 hours with a brightness amplitude of 0.3 magnitude (U=1).^[10] As of 2017, no secure period has been determined.^[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, Pemba measures between 8.71 and 10.75 kilometers in diameter and its surface has an albedo between 0.1316 and 0.196.^{[5][6][7][8][9]}

The Collaborative Asteroid Lightcurve Link adopts Petr Pravec's revised WISE results, that is, an albedo of 0.1316 and a diameter of 10.37 kilometers based on an absolute magnitude of 12.74.^[3][7]

Naming

This minor planet was named for the Pemba Island, Tanzania, part of the Zanzibar Archipelago, which was once under the rule of the Sultan of Zanzibar.^[2] It is located off the East Coast of Africa in the Indian Ocean. The official naming citation was published by the Minor Planet Center in April 1953 (M.P.C. 909).^[12]