694 Ekard

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694 Ekard
694Ekard (Lightcurve Inversion).png
A three-dimensional model of 694 Ekard based on its light curve
Discovered byJoel Hastings Metcalf
Discovery siteTaunton, Massachusetts
Discovery date7 November 1909
MPC designation(694) Ekard
1909 JA
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc106.44 yr (38878 d)
Aphelion3.5372 AU (529.16 Gm)
Perihelion1.8114 AU (270.98 Gm)
2.6743 AU (400.07 Gm)
4.37 yr (1597.4 d)
0° 13m 31.332s / day
Physical characteristics
Mean radius
45.39±2 km[1]
45.39 km[2]
5.925 h (0.2469 d)[1][3]

694 Ekard is a minor planet orbiting the Sun that was discovered by American astronomer Joel Hastings Metcalf on November 7, 1909.

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]


  1. ^ a b c d e Yeomans, Donald K., "694 Ekard", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 7 May 2016.
  2. ^ a b c d Delbo', Marco; Tanga, Paolo (February 2009), "Thermal inertia of main belt asteroids smaller than 100 km from IRAS data", Planetary and Space Science, 57 (2), pp. 259–265, arXiv:0808.0869, Bibcode:2009P&SS...57..259D, doi:10.1016/j.pss.2008.06.015.
  3. ^ a b 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, 62, pp. 512–517, Bibcode:1985Icar...62..512Z, doi:10.1016/0019-1035(85)90191-5.
  4. ^ Ostro, S. J.; et al. (August 1985), "Mainbelt asteroids - Dual-polarization radar observations", Science, 229 (4712), pp. 442–446, Bibcode:1985Sci...229..442O, doi:10.1126/science.229.4712.442, PMID 17738665.
  5. ^ Timerson, Brad; Durech, J.; Pilcher, F.; Albers, J.; Beard, T.; Berger, B.; Berman, B.; Breit, D.; Case, T.; Collier, D.; Dantowitz, R.; Davies, T.; Desmarais, V.; Dunham, D.; Dunham, J.; Garlitz, J.; Garrett, L.; George, T.; Hill, M.; Hughes, Z.; Jacobson, G.; Kozubal, M.; Liu, Y.; Maley, P.; Morgan, W.; Morris, P.; Mroz, G.; Pool, S.; Preston, S.; Shelton, R.; Welch, S.; Westfall, J.; Whitman, A.; Wiggins, P. (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.CS1 maint: uses authors parameter (link)

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