1302 Werra

1302 Werra, provisional designation 1924 SV, is a Themistian asteroid from the outer regions of the asteroid belt, approximately 30 kilometers in diameter. It was discovered on 28 September 1924, by German astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory.^[11] The asteroid was named for the river Werra in central Germany.^[2]

1302 Werra

Discovery[1]
Discovered by	K. Reinmuth
Discovery site	Heidelberg Obs.
Discovery date	28 September 1924
Designations
MPC designation	(1302) Werra
Named after	Werra[2] (river in central Germany)
Alternative designations	1924 SV · 1930 WD
Minor planet category	main-belt · (outer) Themis[3][4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	93.10 yr (34,003 days)
Aphelion	3.6580 AU
Perihelion	2.5677 AU
Semi-major axis	3.1128 AU
Eccentricity	0.1751
Orbital period (sidereal)	5.49 yr (2,006 days)
Mean anomaly	251.95°
Mean motion	0° 10m 46.2s / day
Inclination	2.5958°
Longitude of ascending node	90.142°
Argument of perihelion	354.64°
Physical characteristics
Dimensions	24.35±6.54 km[5] 31.04 km (calculated)[3] 32.18±0.50 km[6] 34.542±0.258 km[7] 35.041±0.114 km[8]
Synodic rotation period	48 h (retracted)[9]
Geometric albedo	0.0710±0.0158[7] 0.076±0.006[8] 0.08 (assumed)[3] 0.10±0.07[5] 0.102±0.004[6]
Spectral type	C (assumed)[3]
Absolute magnitude (H)	10.60[6] · 10.8[7] · 10.90[1][3][5] · 10.99±0.27[10]

Orbit and classification

Werra is a Themistian asteroid that belongs to the Themis family (602),^[3][4] a very large family of carbonaceous asteroids, named after its parent body 24 Themis.^[12]

It orbits the Sun in the outer main-belt at a distance of 2.6–3.7 AU once every 5 years and 6 months (2,006 days; semi-major axis of 3.11 AU). Its orbit has an eccentricity of 0.18 and an inclination of 3° with respect to the ecliptic.^[1] The body's observation arc begins at Heidelberg with its official discovery observation in September 1924.^[11]

Physical characteristics

Werra is an assumed carbonaceous C-type asteroid,^[3] which is the overall spectral type for members of the Themis family.^[12]: 23

Rotation period

In March 2009, a fragmentary lightcurve of Werra was obtained from photometric observations by French amateur astronomer Pierre Antonini. Lightcurve analysis gave a poorly constraint rotation period of 2 days with a brightness amplitude of less than 0.1 magnitude.^[9] The result was later retracted at the Lightcurve Data Base (U=n.a.). As of 2017, no secure period has been obtained.^[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, Werra measures between 24.35 and 35.041 kilometers in diameter and its surface has an albedo between 0.0710 and 0.102.^[5][6][7][8]

The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.08 and calculates a diameter of 31.04 kilometers based on an absolute magnitude of 10.9.^[3]

Naming

This minor planet was named after the river Werra in central Germany. It merges the Fulda in Hannoversch-Münden, Lower Saxony, to form the river Weser. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 119).^[2]