_Neckar.png) Shape model ofNeckar from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | K. Reinmuth |
| Discovery site | Heidelberg Obs. |
| Discovery date | 6 October 1931 |
| Designations | |
| (1223) Neckar | |
Named after | Neckar[2](Germanriver) |
| 1931 TG · 1930 MN 1931 TA1 · 1953 FC A907 VD · A909 BD A917 XC · A917 YA | |
| main-belt[1][3] · (outer) Koronis[4][5][6][7] | |
| Orbital characteristics[3] | |
| Epoch 23 March 2018 (JD 2458200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 109.58yr (40,025 d) |
| Aphelion | 3.0395AU |
| Perihelion | 2.6977 AU |
| 2.8686 AU | |
| Eccentricity | 0.0596 |
| 4.86 yr (1,775 d) | |
| 235.10° | |
| 0° 12m 10.44s / day | |
| Inclination | 2.5448° |
| 40.812° | |
| 15.444° | |
| Physical characteristics | |
| 22.783±0.213 km[8] 23.06±0.56 km[9] 24.68±0.55 km[10] 25.736±0.261 km[11] 26.07±0.86 km[12] 27.96 km(derived)[4] | |
| 7.763 h[13] 7.80±0.06 h[14] 7.81 h[6] 7.82124 h[7] 7.82401±0.00005 h[15] 7.827±0.0036 h[16] 8.6 h(wrong)[a] 8.78 h(wrong)[17] | |
| 0.123[18] 0.1461±0.0271[11] 0.152±0.025[12] 0.170±0.012[10] 0.201±0.011[9] | |
| Tholen =S[3][4] · S[19] B–V = 0.840[3] U–B = 0.405[3] | |
| 10.16±0.10(R)[14] 10.304±0.002(R)[16] 10.51±0.28[19] 10.58[3][9][12][10] 10.66[4][11][17] | |
1223 Neckar, provisional designation1931 TG, is a stony Koronianasteroid from the outer region of theasteroid belt, approximately 25 kilometers (16 miles) in diameter. Discovered byKarl Reinmuth atHeidelberg Observatory in 1931, the asteroid was named for the German riverNeckar. TheS-type asteroid has arotation period of 7.8 hours.[4]
Neckar was discovered on 6 October 1931, by German astronomerKarl Reinmuth atHeidelberg Observatory in southwest Germany.[1] Five nights later, it was independently discovered byFernand Rigaux atUccle in Belgium.[2] TheMinor Planet Center only acknowledges the first discoverer.[1] The asteroid was observed asA907 VD at Heidelberg in November 1907, extending itsobservation arc by 24 years prior to its official discovery observation.[1]
Neckar is a core member of theKoronis family (605),[5] a very large outerasteroid family with nearly co-planar ecliptical orbits. The family, named after158 Koronis, is thought to have been formed at least two billion years ago in a catastrophic collision between two larger bodies. It orbits the Sun in theouter main-belt at a distance of 2.7–3.0 AU once every 4 years and 10 months (1,775 days;semi-major axis of 2.87 AU). Its orbit has aneccentricity of 0.06 and aninclination of 3° with respect to theecliptic.[3]
In theTholen classification,Neckar is a common stonyS-type asteroid.[3] It has also been characterized as an S-type byPan-STARRS.[19]
Best rated rotationallightcurve ofNeckar gave arotation period of 7.763 and 7.81 hours with a brightness variation of 0.18 and 0.45magnitude, respectively (U=3/3).[6][13]Photometric observations taken byRichard Binzel andEd Tedesco in the 1970s and 1980s, however, gave a longer period and are now considered incorrect (U=0/0).[4][17][a]
Two lightcurves in the R-band with a period of 7.80 and 7.8273 hours (Δ0.21/0.28 mag) were also obtained at thePalomar Transient Factory in 2010 and 2014, respectively (U=2/2).[14][16]Neckar's spin axes has been determined several times. The best rated result, from a group led by Polish astronomers, gave twopoles at (70.0°, 45.0°) and (225.0°, 42.0°) inecliptic coordinates.[13]
According to the surveys carried out by the JapaneseAkari satellite and NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission,Neckar measures between 22.783 and 26.07 kilometers in diameter, and its surface has analbedo between 0.146 and 0.201.[8][9][10][11][12] TheCollaborative Asteroid Lightcurve Link adopts an albedo of 0.123 obtained by Morrison in the 1970s,[18] and derives a diameter of 27.96 kilometers using anabsolute magnitude of 10.66.[4]
Thisminor planet was named after the riverNeckar, running through the southwestern parts of Germany and in particular through the city of Heidelberg, location of the discovering observatory. The river origins in the Black Forrest and flows into the Rhine river. Naming citation was first mentioned inThe Names of the Minor Planets byPaul Herget in 1955 (H 113).[2]
