| 词条 | 694 Ekard |
| 释义 |
| minorplanet= yes | image= 694Ekard (Lightcurve Inversion).png | image_size = 265 | caption= A three-dimensional model of 694 Ekard based on its light curve | background= #D6D6D6 | name= 694 Ekard | mpc_name= (694) Ekard | alt_names= 1909 JA | discoverer= Joel Hastings Metcalf | discovered= 7 November 1909 | discovery_site= Taunton, Massachusetts | epoch= 31 July 2016 (JD 2457600.5) | orbit_ref= | eccentricity= 0.32265 | semimajor= {{Convert|2.6743|AU|Gm|abbr=on}} | perihelion= {{Convert|1.8114|AU|Gm|abbr=on}} | aphelion= {{Convert|3.5372|AU|Gm|abbr=on|lk=on}} | period= 4.37 yr (1597.4 d) | inclination= 15.849° | asc_node= 230.116° | arg_peri= 111.400° | mean_anomaly= 201.11° | dimensions= | mean_radius= {{val|45.39|2}} km 45.39 km[3] | rotation= {{Convert|5.925|h|d|abbr=on|lk=on}}[5] | spectral_type= | abs_magnitude= 9.17[3] | albedo= 0.046[3] {{val|0.0460|0.004}} | mean_motion= {{Deg2DMS|0.22537|sup=ms}} / day | observation_arc= 106.44 yr (38878 d) | uncertainty= 0 }} 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.[5] 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.[3]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.[12] 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 {{Val|90|6|u=km}}.[13] References1. ^1 {{citation | title=Occultations by 81 Terpsichore and 694 Ekard in 2009 at Different Rotational Phase Angles | authors=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. | journal=The Minor Planet Bulletin | volume=37 | issue=4 | pages=140−142 | date=October 2010 | bibcode=2010MPBu...37..140T | postscript=. }} [1][2][3][4]2. ^1 2 3 4 {{Citation | last1 = Delbo' | first1 = Marco | last2 = Tanga | first2 = Paolo | title = Thermal inertia of main belt asteroids smaller than 100 km from IRAS data | work = Planetary and Space Science | volume = 57 | issue = 2 | pages = 259–265 |date=February 2009 | doi = 10.1016/j.pss.2008.06.015 | bibcode = 2009P&SS...57..259D | postscript= .|arxiv = 0808.0869 }} 3. ^1 2 {{Citation | last1 = Zeigler | first1 = K. W. | last2 = Florence | first2 = W. B. | title = Photoelectric photometry of asteroids 9 Metis, 18 Melpomene, 60 Echo, 116 Sirona, 230 Athamantis, 694 Ekard, and 1984 KD | work = Icarus | volume = 62 | pages = 512–517 |date=June 1985 | doi = 10.1016/0019-1035(85)90191-5 | bibcode = 1985Icar...62..512Z | postscript= .}} 4. ^1 {{Citation | last1 = Ostro | first1 = S. J. | last2 = Campbell | first2 = D. B. | last3 = Shapiro | first3 = I. I. | display-authors = 1 | title = Mainbelt asteroids - Dual-polarization radar observations | work = Science | volume = 229 | pages = 442–446 |date=August 1985 | doi = 10.1126/science.229.4712.442 | bibcode = 1985Sci...229..442O | postscript= . | pmid=17738665 | issue=4712}} }} External links
5 : Background asteroids|Discoveries by Joel Metcalf|Named minor planets|CP:-type asteroids (Tholen)|Astronomical objects discovered in 1909 |
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