1175 Margo

1175 Margo, provisional designation 1930 UD, is a stony background asteroid from the outermost regions of the asteroid belt, approximately 24 kilometers in diameter. It was discovered on 17 October 1930, by astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory in southwest Germany.^[15] The meaning of the asteroids's name is unknown.^[2]

1175 Margo

Modelled shape of Margo from its lightcurve
Discovery[1]
Discovered by	K. Reinmuth
Discovery site	Heidelberg Obs.
Discovery date	17 October 1930
Designations
MPC designation	(1175) Margo
Named after	unknown[2]
Alternative designations	1930 UD · 1953 VK 1957 KU · A907 VA
Minor planet category	main-belt · (outer)[1][3] background[4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	109.91 yr (40,146 days)
Aphelion	3.4345 AU
Perihelion	2.9979 AU
Semi-major axis	3.2162 AU
Eccentricity	0.0679
Orbital period (sidereal)	5.77 yr (2,107 days)
Mean anomaly	61.257°
Mean motion	0° 10m 15.24s / day
Inclination	16.307°
Longitude of ascending node	237.19°
Argument of perihelion	102.79°
Physical characteristics
Dimensions	22.99±0.85 km[5] 24.266±0.276 km[6] 25.394±0.250 km[7] 58.29 km (calculated)[3]
Synodic rotation period	6.01±0.02 h[8] 6.01±0.03 h[9] 6.0136±0.0002 h[9] 6.01375±0.00005 h[10] 6.015±0.001 h[11] 6.017±0.001 h[12] 11.99±0.03 h[13]
Geometric albedo	0.057 (assumed)[3] 0.2409±0.0329[7] 0.249±0.042[6] 0.302±0.026[5]
Spectral type	S[14] · C (assumed)[3]
Absolute magnitude (H)	9.9[3] · 10.0[1] · 10.06±0.23[14] · 10.20[5][7]

Orbit and classification

Margo is a non-family asteroid from the main belt's background population.^[4] It orbits the Sun in the outermost asteroid belt at a distance of 3.0–3.4 AU once every 5 years and 9 months (2,107 days; semi-major axis of 3.22 AU). Its orbit has an eccentricity of 0.07 and an inclination of 16° with respect to the ecliptic.^[1]

The body's observation arc begins with its first identification as A907 VA at Heidelberg in November 1907, almost 23 years prior to its official discovery observation.^[15]

Physical characteristics

Margo has been characterized as a stony S-type asteroid by Pan-STARRS photometric survey.^[14] Conversely, the Collaborative Asteroid Lightcurve Link (CALL) assumes it to be a carbonaceous C-type.^[3]

Rotation period and poles

In November 2005, a rotational lightcurve of Margo was obtained from photometric observations by astronomers Raymond Poncy (177), Gino Farroni, Pierre Antonini, Donn Starkey (H63) and Raoul Behrend. Lightcurve analysis gave a well-defined rotation period of 6.0136 hours with a brightness amplitude of 0.31 magnitude (U=3).^[9] Since then, several other, lower-rated lightcurves have been published (U=3-/2+/2+/2/2).^{[8][9][11][12][13]}

In 2016, the asteroid lightcurve has also been modeled using photometric data from various sources. It gave a concurring period of 6.01375 hours and two spin axis in ecliptic coordinates of (184.0°, −43.0°) and (353.0°, −17.0°).^[10]

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, Margo measures between 22.99 and 25.394 kilometers in diameter and its surface has an albedo between 0.2409 and 0.302.^[5][6][7] CALL assumes a standard albedo for carbonaceous asteroids of 0.057 and consequently calculates a much larger diameter of 58.29 kilometers based on an absolute magnitude of 9.9.^[3]

Naming

This minor planet was named by the discoverer Karl Reinmuth. Any reference of its name to a person or occurrence is unknown.^[2]

Unknown meaning

Among the many thousands of named minor planets, Margo is one of 120 asteroids, for which no official naming citation has been published. All of these low-numbered asteroids have numbers between 164 Eva and 1514 Ricouxa and were discovered between 1876 and the 1930s, predominantly by astronomers Auguste Charlois, Johann Palisa, Max Wolf and Karl Reinmuth.^[16]