1337 Gerarda

1337 Gerarda, provisional designation 1934 RA₁, is a dark background asteroid from the outer regions of the asteroid belt, approximately 40 kilometers in diameter. It was discovered on 9 September 1934, by Dutch astronomer Hendrik van Gent at the Union Observatory in Johannesburg, South Africa.^[15] The asteroid was named after Gerarda Prins, the wife of an orbit computer at Leiden Observatory.^[2]

1337 Gerarda

Modelled shape of Gerarda from its lightcurve
Discovery[1]
Discovered by	H. van Gent
Discovery site	Johannesburg Obs.
Discovery date	9 September 1934
Designations
MPC designation	(1337) Gerarda
Named after	Gerarda Prins[2] (wife of astronomer)
Alternative designations	1934 RA1 · 1942 EE1
Minor planet category	main-belt · (outer)[3] background[4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	83.06 yr (30,337 days)
Aphelion	3.1978 AU
Perihelion	2.6247 AU
Semi-major axis	2.9113 AU
Eccentricity	0.0984
Orbital period (sidereal)	4.97 yr (1,814 days)
Mean anomaly	257.78°
Mean motion	0° 11m 54.24s / day
Inclination	17.979°
Longitude of ascending node	160.29°
Argument of perihelion	201.86°
Physical characteristics
Dimensions	35.56±11.35 km[5] 38.84 km (derived)[3] 38.86±3.6 km[6] 40.875±0.305 km[7] 40.91±0.49 km[8] 41.53±0.48 km[9] 43.22±12.45 km[10] 46.464±0.379 km[11]
Synodic rotation period	12.462±0.0145 h[12] 12.52 h[13]
Geometric albedo	0.0297±0.0042[11] 0.03±0.02[10] 0.034±0.007[9] 0.04±0.04[5] 0.042±0.001[8] 0.0425 (derived)[3] 0.0441±0.010[6]
Spectral type	P[11] · X[14] C (assumed)[3]
Absolute magnitude (H)	10.88±0.45[14] · 10.970±0.001 (R)[12] · 11.06[6][8] · 11.10[3][11][13] · 11.20[1][9][10] · 11.29[5]

Orbit and classification

Gerarda is a non-family asteroid from the main belt's background population.^[4] It orbits the Sun in the outer main-belt at a distance of 2.6–3.2 AU once every 4 years and 12 months (1,814 days; semi-major axis of 2.91 AU). Its orbit has an eccentricity of 0.10 and an inclination of 18° with respect to the ecliptic.^[1]

The body's observation arc begins with its official discovery observation at Johannesburg.^[15]

Physical characteristics

Gerarda has been characterized as a dark and primitive P-type asteroid by the Wide-field Infrared Survey Explorer (WISE).^[11] It has also been classified as an X-type asteroid by Pan-STARRS photometric survey,^[14] while the Collaborative Asteroid Lightcurve Link (CALL) assumes it to be a carbonaceous C-type asteroid.^[3]

Rotation period

In November 1984, a first rotational lightcurve of Gerarda was obtained from photometric observations by American astronomer Richard Binzel. Lightcurve analysis gave a rotation period of 12.52 hours with a brightness variation of 0.23 magnitude (U=2).^[13] A similar period of 12.462 with an identical amplitude of 0.23 was measured by astronomers at the Palomar Transient Factory in June 2012 (U=2).^[12]

Diameter and albedo

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's WISE telescope, Gerarda measures between 35.56 and 46.464 kilometers in diameter and its surface has an albedo between 0.0297 and 0.0441.^{[5][6][7][8][9][10][11]}

CALL derives an albedo of 0.0425 and a diameter of 38.84 kilometers based on an absolute magnitude of 11.10.^[3]

Naming

This minor planet was named by Dutch astronomer Gerrit Pels, who computed this asteroid's orbit. It was named after Gerarda Prins, the wife of G. Prins, an orbit computer at Leiden Observatory.^[2] The author of the Dictionary of Minor Planet Names, Lutz Schmadel, learned about the naming circumstances from Ingrid van Houten-Groeneveld, who was herself a long-time staff member at the Leiden Observatory.^[2]