3682 Welther

3682 Welther, provisional designation A923 NB, is a background asteroid from the central regions of the asteroid belt, approximately 19 kilometers (12 miles) in diameter. It was discovered on 12 July 1923, by German astronomer Karl Reinmuth at the Heidelberg Observatory in southwest Germany.^[1] The asteroid has a rotation period of 3.6 hours.^[7] It was named after Barbara Welther, an American historian of science at CfA.^[1]

3682 Welther

Discovery[1]
Discovered by	K. Reinmuth
Discovery site	Heidelberg Obs.
Discovery date	12 July 1923
Designations
MPC designation	(3682) Welther
Named after	Barbara Welther[1] (American historian of science)
Alternative designations	A923 NB · 1951 YO 1978 NP3 · 1984 AA
Minor planet category	main-belt[1][2] · (middle) background[3]
Orbital characteristics[2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc	94.79 yr (34,621 d)
Aphelion	3.6413 AU
Perihelion	1.8769 AU
Semi-major axis	2.7591 AU
Eccentricity	0.3197
Orbital period (sidereal)	4.58 yr (1,674 d)
Mean anomaly	210.16°
Mean motion	0° 12m 54.36s / day
Inclination	13.579°
Longitude of ascending node	255.47°
Argument of perihelion	113.95°
Physical characteristics
Mean diameter	11.13±3.57 km[4] 16.83±4.95 km[5] 19.087±0.229 km[6] 19.24 km (derived)[7] 19.257±0.110 km[8] 19.32±0.7 km[9] 19.34±0.30 km[10]
Synodic rotation period	3.595±0.003 h[11] 3.597 h[12] 3.5973±0.0001 h[11] 3.5973±0.0003 h[13][a] 3.599±0.003 h[14]
Geometric albedo	0.0997 (derived)[7] 0.1189±0.009[9] 0.1198±0.0132[8] 0.120±0.004[10] 0.133±0.123[5] 0.138±0.016[6] 0.26±0.18[4]
Spectral type	C (assumed)[7]
Absolute magnitude (H)	11.50[8][9][10] 11.68[5] 11.7[2][7] 11.86[4] 12.39±0.52[15]

Orbit and classification

Welther is a non-family asteroid from the main belt's background population.^[3] It orbits the Sun in the central main-belt at a distance of 1.9–3.6 AU once every 4 years and 7 months (1,674 days; semi-major axis of 2.76 AU). Its orbit has an eccentricity of 0.32 and an inclination of 14° with respect to the ecliptic.^[2]

The body's observation arc begins at Heidelber and Vienna Observatory in August 1928, or four weeks after its official discovery observation at Heidelberg.^[1]

Physical characteristics

Welther is an assumed C-type asteroid.^[7]

Rotation period

Several rotational lightcurves of Welther have been obtained from photometric observations since 2001.^{[11][12][13][14]} Analysis of the best-rated lightcurves gave a rotation period of 3.5973 hours with a brightness amplitude of 0.22 and 0.21 magnitude, respectively (U=3-/3).^[11][13][a] The observing French amateur astronomers also suspected the asteroid to be a binary system.^[11]

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 Wide-field Infrared Survey Explorer, Welther measures between 11.13 and 19.34 kilometers in diameter and its surface has an albedo between 0.1189 and 0.26.^{[4][5][6][8][9][10]}

The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0997 and a diameter of 19.24 kilometers based on an absolute magnitude of 11.7.^[7]

Naming

This minor planet was named after American Barbara Welther (born 1938), a historian of science at the Harvard–Smithsonian Center for Astrophysics (CfA).^[1] The official naming citation was proposed by CfA's Planetary Sciences division and published by the Minor Planet Center on 1 September 1993 (M.P.C. 22499).^[16]

Notes

1. Lightcurve plot of 3682 Welther, Palmer Divide Observatory, B. D. Warner (2001); Collaboration with R.D. Stephens (lead), P. Pravec, P. Kusnirak, et al. Only PDO data are shown. Rotation period 3.5973 hours with a brightness amplitude of 0.21±0.01 mag. Also see summary at the LCDB