694 Ekard
694 Ekard is a minor planet orbiting the Sun that was discovered by American astronomer Joel Hastings Metcalf on November 7, 1909.
.png.webp) A three-dimensional model of 694 Ekard based on its light curve | |
| Discovery | |
|---|---|
| Discovered by | Joel Hastings Metcalf |
| Discovery site | Taunton, Massachusetts |
| Discovery date | 7 November 1909 |
| Designations | |
| (694) Ekard | |
| 1909 JA | |
| Orbital characteristics[1] | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 106.44 yr (38878 d) |
| Aphelion | 3.5372 AU (529.16 Gm) |
| Perihelion | 1.8114 AU (270.98 Gm) |
| 2.6743 AU (400.07 Gm) | |
| Eccentricity | 0.32265 |
| 4.37 yr (1597.4 d) | |
| 201.11° | |
| 0° 13m 31.332s / day | |
| Inclination | 15.849° |
| 230.116° | |
| 111.400° | |
| Physical characteristics | |
Mean radius | 45.39±2 km[1] 45.39 km[2] |
| 5.925 h (0.2469 d)[1][3] | |
| 0.046[2] 0.0460±0.004[1] | |
| 9.17[1][2] | |
Photometric observations of this asteroid gave a light curve with a period of 5.925 hours and a brightness variation of 0.50 in magnitude.[3] Measurements of the thermal inertia of 694 Ekard give a value of around 100–140 J m−2 K−1 s−1/2, compared to 50 for lunar regolith and 400 for coarse sand in an atmosphere.[2]
13-cm radar observations of this asteroid from the Arecibo Observatory between 1980 and 1985 were used to produce a diameter estimate of 101 km.[4] Four separate stellar occultation events involving this asteroid were observed from multiple sites in 2009. The resulting chords matched a least squares equivalent diameter of 90±6 km.[5]
References
- Yeomans, Donald K., "694 Ekard", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 7 May 2016.
- Delbo', Marco; Tanga, Paolo (February 2009), "Thermal inertia of main belt asteroids smaller than 100 km from IRAS data", Planetary and Space Science, vol. 57, no. 2, pp. 259–265, arXiv:0808.0869, Bibcode:2009P&SS...57..259D, doi:10.1016/j.pss.2008.06.015.
- Zeigler, K. W.; Florence, W. B. (June 1985), "Photoelectric photometry of asteroids 9 Metis, 18 Melpomene, 60 Echo, 116 Sirona, 230 Athamantis, 694 Ekard, and 1984 KD", Icarus, vol. 62, pp. 512–517, Bibcode:1985Icar...62..512Z, doi:10.1016/0019-1035(85)90191-5.
- Ostro, S. J.; et al. (August 1985), "Mainbelt asteroids - Dual-polarization radar observations", Science, vol. 229, no. 4712, pp. 442–446, Bibcode:1985Sci...229..442O, doi:10.1126/science.229.4712.442, PMID 17738665.
- Timerson, Brad; Durech, J.; Pilcher, F.; et al. (October 2010), "Occultations by 81 Terpsichore and 694 Ekard in 2009 at Different Rotational Phase Angles", The Minor Planet Bulletin, 37 (4): 140−142, Bibcode:2010MPBu...37..140T.
External links
- 694 Ekard at AstDyS-2, Asteroids—Dynamic Site
- 694 Ekard at the JPL Small-Body Database