335 Roberta

Roberta (minor planet designation: 335 Roberta) is a large main belt asteroid. It was discovered on 1 September 1892, by German astronomer Anton Staus at Heidelberg Observatory.[3] Roberta was the 12th asteroid that was discovered using photography, and the only asteroid discovery made by Staus.[4]

335 Roberta

Orbital diagram
Discovery
Discovered by	Anton Staus
Discovery date	1 September 1892
Designations
MPC designation	(335) Roberta
Named after	Carl Robert Osten-Sacken
Alternative designations	1892 C
Minor planet category	Main belt
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	123.58 yr (45137 d)
Aphelion	2.9014 AU (434.04 Gm)
Perihelion	2.04926 AU (306.565 Gm)
Semi-major axis	2.47530 AU (370.300 Gm)
Eccentricity	0.17212
Orbital period (sidereal)	3.89 yr (1422.5 d)
Average orbital speed	18.93 km/s
Mean anomaly	355.460°
Mean motion	0° 15m 11.095s / day
Inclination	5.1005°
Longitude of ascending node	148.454°
Argument of perihelion	140.006°
Earth MOID	1.03587 AU (154.964 Gm)
Jupiter MOID	2.2733 AU (340.08 Gm)
TJupiter	3.456
Physical characteristics
Dimensions	89.07±2.0 km[1]
Synodic rotation period	12.054 h (0.5023 d)
Geometric albedo	0.0580±0.003[1] 0.058[2]
Spectral type	B–V = 0.624 U–B = 0.235 FP (Tholen) B (SMASS)[1]
Absolute magnitude (H)	8.96[1]

Photometric observations of this asteroid from multiple sites during 2007 gave a light curve with a period of 12.054 ± 0.003 hours and a brightness variation of 0.13 ± 0.02 in magnitude. This agrees with a result reported in 1992, but differs from period estimates of 8.03 hours and 4.349 reported in 1987 and 2001, respectively.[5]

Under the SMASS classification taxonomy, this asteroid is listed as a B-type; a group that combines both the Tholen B and F types. The spectrum of this object suggests the presence of magnetite (Fe₃O₄), which gives it the spectrally-blue coloration that is a characteristic of this SMASS class. The spectrum of this asteroid also displays a band feature near 2.9 μm that indicate the presence of a hydrated mineral. This suggests that the asteroid has undergone significant water-based alteration.[2]

335 Roberta was identified as one of three asteroids that were likely to be a parent body for chondrites along with 449 Hamburga and 304 Olga.[6] All three asteroids were known to have low-albedo (not reflect as much light) and be close to "meteorite producing resonances".[6] Chrondrites are the most common type of meteor found on Earth, accounting for over 80% of all meteors.[7] They are named for the tiny spherical silicate particles that are found inside them (those particles are called chondrules).[7]