801 Helwerthia

801 Helwerthia is a C-type asteroid orbiting in the Main belt near the Eunomia family. However, it is not a family member but an un-related interloper in the region because its composition is inconsistent with membership. Its diameter is about 33 km, its albedo around 0.038.^[2] An international team of astronomers observed this minor planet photometrically in 2012, determining a rotation period of 23.93±0.01 h with an amplitude of 0.15±0.03 in magnitude.^[3]

801 Helwerthia

Discovery
Discovered by	Max Wolf
Discovery site	Heidelberg Observatory
Discovery date	20 March 1915
Designations
MPC designation	(801) Helwerthia
Alternative designations	1915 WQ; A924 OD; 1925 RG; 1970 GS1
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	101.08 yr (36918 d)
Aphelion	2.8087 AU (420.18 Gm)
Perihelion	2.4007 AU (359.14 Gm)
Semi-major axis	2.6047 AU (389.66 Gm)
Eccentricity	0.078337
Orbital period (sidereal)	4.20 yr (1535.4 d)
Mean anomaly	47.6362°
Mean motion	0° 14m 4.056s / day
Inclination	14.130°
Longitude of ascending node	185.973°
Argument of perihelion	335.076°
Earth MOID	1.41172 AU (211.190 Gm)
Jupiter MOID	2.17333 AU (325.126 Gm)
TJupiter	3.366
Physical characteristics
Mean radius	16.615±1.25 km
Synodic rotation period	23.93 h (0.997 d)
Geometric albedo	0.0384±0.007
Absolute magnitude (H)	11.55