Time to Perform the Physical Observations of Asteroids |
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Authors: | Gao Jian Zhu Jin |
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Institution: | (1) Department of Astronomy, Beijing Normal University, Beijing, 100875, P. R. China;(2) National Astronomical Observatories, CAS, Beijing, 100012, P. R. China |
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Abstract: | The astrometric observations of asteroids are often performednear their opposition, where they have faster apparent motions andbrighter visual magnitudes. However, the physical observations ofasteroids (photometric and spectral) often require longer exposuretimes as well as brighter magnitudes for better signal-to-noiseratio, which are combined effects of both apparent moving speedsand visual magnitudes. We derive the equations of the apparentmotion of asteroid in geocentric ecliptic coordinates. Comparisonof the apparent magnitudes of asteroid at opposition and atstationary shows that the magnitude differences in the two casesare around 1 magnitude in average for most main belt asteroids,but are much larger for Near Earth Asteroids. Combining withcomparison of asteroid apparent motion, the proper time forasteroid physical observation in different cases are discussed. |
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Keywords: | Apparent motion asteroid asteroid physical observation |
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