| Discovery[1] | |
|---|---|
| Discovered by | C. Jackson |
| Discovery site | Johannesburg Obs. |
| Discovery date | 19 March 1934 |
| Designations | |
| (1319) Disa | |
| Pronunciation | /ˈdaɪsə/[2] |
Named after | Disa(orchid –flowering plant)[3] |
| 1934 FO · 1929 GE 1970 FM · A908 EA | |
| main-belt · (outer)[4] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 109.20 yr (39,885 days) |
| Aphelion | 3.6026AU |
| Perihelion | 2.3684 AU |
| 2.9855 AU | |
| Eccentricity | 0.2067 |
| 5.16yr (1,884 days) | |
| 41.069° | |
| 0° 11m 27.96s / day | |
| Inclination | 2.8007° |
| 256.10° | |
| 316.25° | |
| Physical characteristics | |
| Dimensions | 16.88±1.12 km[5] 24.00±0.37 km[6] 25.651±0.321 km[7] 25.894±0.180 km[8] 40.33 km(calculated)[4] |
| 7.080±0.003h[9][a] 7.082±0.001 h[10] 7.0820±0.0077 h[11] | |
| 0.057(assumed)[4] 0.0959±0.0034[8] 0.097±0.012[7] 0.116±0.004[6] 0.391±0.038[5] | |
| P[8] · C[4] | |
| 10.391±0.002(R)[11] · 10.50[5] · 10.7[1][4] · 11.1[6][8] | |
1319 Disa, provisional designation1934 FO, is a carbonaceousasteroid from the outer region of theasteroid belt, approximately 25 kilometers in diameter. It was discovered on 19 March 1934, by English-born, South African astronomerCyril Jackson atJohannesburg Observatory in South Africa.[12] It is named for the orchidDisa.[3]
Disa orbits the Sun in theouter main-belt at a distance of 2.4–3.6 AU once every 5 years and 2 months (1,884 days). Its orbit has aneccentricity of 0.21 and aninclination of 3° with respect to theecliptic.[1] It was first identified asA908 EA atHeidelberg Observatory in 1908. The body'sobservation arc begins in 1929, when it was identified as1929 GE at the discovering observatory, 6 years prior to its official discovery observation.[12]
A rotationallightcurve ofDisa was obtained by American astronomerBrian D. Warner at his Palmer Divide Observatory in March 2006, and by French amateur astronomerPierre Antonini in February 2011, respectively. Analysis of both lightcurves gave a well-definedrotation period of 7.08 hours with a brightness variation of 0.26 and 0.27magnitude (U=3/3).[9][10][a]
In September 2013, photometric observations in the R-band at thePalomar Transient Factory gave a concurring lightcurve of 7.082 hours and an amplitude of 0.24 magnitude (U=2).[11]
According to the surveys carried out by the JapaneseAkari satellite, and the 2014-results by NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission,Disa measures 24.00 and 25.65 kilometers in diameter, and its surface has analbedo of 0.116 and 0.097, respectively.[6]
TheCollaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceousC-type asteroids of 0.057 and calculates a diameter of 40.33 kilometers with anabsolute magnitude of 10.7.[4] Preliminary results by NEOWISE also characterized the body as a dark and reddishP-type asteroid.[8]
Thisminor planet was named afterDisa, also known as "African weed-orchid", a large genus of more than a hundred tropicalorchids, common in southern Africa.[3] In 1955, this naming citation was also published byPaul Herget inThe Names of the Minor Planets (H 120).[3]
