249 Ilse

249 Ilse is a Main belt asteroid. It has an unusually slow rotation period, about 3.5 days.

DiscoveredbyC. H. F. Peters

Discoverydate16 August 1885

MPCdesignation

(249) Ilse

PronunciationGerman: [ˈɪlzə]^[1]

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249 Ilse

3D model based on lightcurve data
Discovery
Discovered by	C. H. F. Peters
Discovery date	16 August 1885
Designations
MPC designation	(249) Ilse
Pronunciation	German: [ˈɪlzə][1]
Named after	Ilse
Alternative designations	A885 QA, 1973 PB
Minor planet category	Main belt
Orbital characteristics[2]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	130.59 yr (47699 d)
Aphelion	2.89450 AU (433.011 Gm)
Perihelion	1.85992 AU (278.240 Gm)
Semi-major axis	2.37721 AU (355.626 Gm)
Eccentricity	0.21760
Orbital period (sidereal)	3.67 yr (1338.8 d)
Average orbital speed	19.31 km/s
Mean anomaly	223.964°
Mean motion	0° 16m 8.065s / day
Inclination	9.61979°
Longitude of ascending node	334.727°
Argument of perihelion	42.3241°
Physical characteristics
Dimensions	34.83±1.1 km
Synodic rotation period	84.94 h (3.539 d)
Geometric albedo	0.0428±0.003
Temperature	unknown
Absolute magnitude (H)	11.33

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It was discovered by C. H. F. Peters on August 16, 1885, in Clinton, New York and was named after Ilse, a legendary German princess.

Due to the long rotation period, a possible asteroidal satellite of Ilse was proposed by R. P. Binzel in 1987 however no evidence of this has been found.^[3]