694 Ekard

694 Ekard
A three-dimensional model of 694 Ekard based on its light curve
Discovery
Discovered byJoel Hastings Metcalf
Discovery siteTaunton, Massachusetts
Discovery date7 November 1909
Designations
(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)
Eccentricity0.32265
4.37 yr (1597.4 d)
201.11°
0° 13m 31.332s / day
Inclination15.849°
230.116°
111.400°
Physical characteristics
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]

694 Ekard is a minor planet orbiting the Sun that was discovered by American astronomer Joel Hastings Metcalf on November 7, 1909. The asteroid's name comes from the reverse spelling of Drake University in Des Moines, Iowa, where Seth Barnes Nicholson and his wife calculated its orbit.

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 Cite error: The named reference JPL was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Delbo2009 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Zeigler1985 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Ostro1985 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Timerson2010 was invoked but never defined (see the help page).