| Discovery[1] | |
|---|---|
| Discovered by | M. F. Wolf |
| Discovery site | Heidelberg Obs. |
| Discovery date | 30 October 1918 |
| Designations | |
| (919) Ilsebill | |
Named after | Fairy tale character "Ilsebill" (The Fisherman and his Wife)[2] |
| A918 UD · 1935 JG 1950 RP · 1950 SE 1950 TN · 1972 MA 1918 EQ | |
| main-belt[1][3] · (middle) background[4][5] | |
| Orbital characteristics[3] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 101.19yr (36,960 d) |
| Aphelion | 3.0033AU |
| Perihelion | 2.5408 AU |
| 2.7721 AU | |
| Eccentricity | 0.0834 |
| 4.62 yr (1,686 d) | |
| 14.861° | |
| 0° 12m 48.96s / day | |
| Inclination | 8.1657° |
| 229.83° | |
| 156.02° | |
| Physical characteristics | |
| 5.0325±0.0011 h[9] | |
| 11.4[1][3] | |
919 Ilsebill (prov. designation:A918 UDor1918 EQ) is a darkbackground asteroid from the central region of theasteroid belt. It was discovered on 30 October 1918, by astronomerMax Wolf at theHeidelberg-Königstuhl State Observatory in southwest Germany.[1] The carbonaceousC-type asteroid has a shortrotation period of 5.0 hours and measures approximately 33 kilometers (21 miles) in diameter. It was named after "Ilsebill", a character in the fairy taleThe Fisherman and his Wife by theBrothers Grimm.[2]
Ilsebill is a non-family asteroid of the main belt'sbackground population when applying thehierarchical clustering method to itsproper orbital elements.[4][5] It orbits the Sun in thecentral asteroid belt at a distance of 2.5–3.0 AU once every 4 years and 7 months (1,686 days;semi-major axis of 2.77 AU). Its orbit has aneccentricity of 0.08 and aninclination of 8° with respect to theecliptic.[3] The body'sobservation arc begins atHeidelberg Observatory with its official discovery observation on 30 October 1918.[1]
Thisminor planet was named after the character "Ilsebill" in the fairy taleThe Fisherman and his Wife (German:Von dem Fischer und seiner Frau) by theBrothers Grimm. The asteroid was named likely after the discoverer's death in 1932, upon a proposal made by his widowGisela Wolf, and subsequently published byARI (RI 1013). Thenaming was also mentioned inThe Names of the Minor Planets byPaul Herget in 1955 (H 89).[2]
In the Bus–BinzelSMASS classification and in theSDSS-based taxonomy,Ilsebill is a common, carbonaceousC-type asteroid.[3][5][10]
In October 2010, a rotationallightcurve ofIlsebill was obtained fromphotometric observations by Zachary Pligge, Ben Hall and Richard Ditteon at the U.S.Oakley Observatory (916) in Indiana. Lightcurve analysis gave a well-definedrotation period of5.0325±0.0011 hours with a brightness variation of0.25±0.02magnitude (U=3).[9] In September 2010, a similar, though lower rated period of5.034±0.0010 hours with an amplitude of0.24 was determined by astronomers at thePalomar Transient Factory in California (U=2).[11][12]
A modeled lightcurve using photometric data from theLowell Photometric Database and from theWide-field Infrared Survey Explorer (WISE) was published in 2018. It gave a concurring sidereal period of5.03348±0.00002 hours and includes a partialspin axis at (β1 = −53.0°) inecliptic coordinates (λ, β).[13]
According to the survey carried out by the Infrared Astronomical SatelliteIRAS, the JapaneseAkari satellite, and theNEOWISE mission of NASA'sWISE telescope,Ilsebill measures (27.65±1.7), (33.41±0.49) and (33.500±0.071) kilometers in diameter and its surface has a lowalbedo of (0.0698±0.010), (0.048±0.002) and (0.047±0.010), respectively.[6][7][8] TheCollaborative Asteroid Lightcurve Link derives its estimate from IRAS, that is, an albedo of 0.0638 and a diameter of 27.62 km based on anabsolute magnitude of 11.4.[11] Further published mean-diameters by the WISE team include (29.37±9.40 km), (32.598±7.912 km), (33.17±0.16 km), (34.444±0.254 km) and (38.64±12.97 km) with albedos between (0.027±0.046) and (0.05±0.03).[5][11]
