| Discovery[1] | |
|---|---|
| Discovered by | M. F. Wolf |
| Discovery site | Heidelberg Obs. |
| Discovery date | 16 February 1920 |
| Designations | |
| (927) Ratisbona | |
| Pronunciation | /rætɪsˈboʊnə/ |
Named after | Regensburg (German city)[2] |
| A920 DB · 1920 GO 1958 VD · 1958 XQ | |
| main-belt[1] · (outer)[3] background[4][5] | |
| Orbital characteristics[3] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 99.57yr (36,368 d) |
| Aphelion | 3.5095AU |
| Perihelion | 2.9476 AU |
| 3.2285 AU | |
| Eccentricity | 0.0870 |
| 5.80 yr (2,119 d) | |
| 88.007° | |
| 0° 10m 11.64s / day | |
| Inclination | 14.572° |
| 7.6887° | |
| 171.36° | |
| Physical characteristics | |
| 12.986±0.003 h[9] | |
| 9.3[1][3] | |
927 Ratisbona is a large and darkbackground asteroid, approximately 76 kilometers (47 miles) in diameter, located in the outer region of theasteroid belt. It was discovered on 16 February 1920, by astronomerMax Wolf at theHeidelberg Observatory in southwest Germany.[1] The carbonaceousC-type asteroid (CB) has arotation period of 12.99 hours and is rather spherical in shape. It was named after the Bavarian city ofRegensburg.[2]
Ratisbona 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 theouter asteroid belt at a distance of 2.9–3.5 AU once every 5 years and 10 months (2,119 days;semi-major axis of 3.23 AU). Its orbit has aneccentricity of 0.09 and aninclination of 15° with respect to theecliptic.[3] The body'sobservation arc begins atHeidelberg-Königstuhl State Observatory on 17 February 1920, the night after its official discovery observation.[1]
Thisminor planet was named after theLatin name of the German city ofRegensburg in Bavaria, where astronomerJohannes Kepler died in 1630. Thenaming was mentioned in the astronomical journalAstronomische Nachrichten in 1930 (AN 240, 135).[2]
In theTholen classification,Ratisbona is most similar to a common, carbonaceousC-type asteroid, and somewhat similar to a brighterB-type asteroid, based on a nosy spectrum (CB:).[3][5]
Over the course of seven nights in January 2018, a rotationallightcurve ofRatisbona was obtained fromphotometric observations byTom Polakis at the Command Module Observatory (V02) in Arizona. Lightcurve analysis gave arotation period of12.986±0.003 hours with a low brightness variation of0.15±0.02magnitude, indicative of a regular, spherical shape (U=3-).[11] The result supersedes a period of12.9938±0.0007 hours with an amplitude of0.12±0.01 magnitude determined byRené Roy,Raoul Behrend,Pierre Antonini and Donn Starkey in October 2004 (U=2).[12]
According to the survey carried out by the Infrared Astronomical SatelliteIRAS, theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer (WISE), and the JapaneseAkari satellite,Ratisbona measures (67.57±1.3), (75.892±0.187) and (78.20±1.11) kilometers in diameter and its surface has a very lowalbedo of (0.0591±0.002), (0.046±0.004) and (0.044±0.002), respectively.[6][7][8]
TheCollaborative Asteroid Lightcurve Link adopts the results from IRAS, that is, a albedo of 0.0591 and a diameter of 67.57 km based on anabsolute magnitude of 9.54.[9] Further published mean-diameters and albedos by the WISE team include (73.204±1.485 km) and (84.872±1.352 km) and albedos of (0.050±0.011) and (0.0375±0.0027).[5][9] Anasteroid occultation, observed on 13 September 2014, gave a best-fit ellipse dimension of 78.0 × 78.0 kilometers.[5] These timed observations are taken when the asteroid passes in front of a distant star. However the quality of the measurement is rated poorly.[5]
