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J. L. Elliot, S. D. Kern (MIT)
Large KBOs can be probed for atmospheres and nearby companions through observation of targeted stellar occultations. Their diameters can also be measured with this technique with multiple chords, or a single chord in conjunction with accurate astrometry. By ``targeted stellar occultations," we mean those events that can be predicted in advance for specific KBOs of interest, from knowledge of their orbits and coordinates of the stars that lie near their projected path. Prediction of these occultations will be difficult, but within demonstrated capabilities. For example, the radius of a 600-km diameter KBO at a distance of 40 AU subtends an angle of 0.01 arcsec, and occultation predictions of this accuracy have been routinely achieved in recent years for Chiron, Triton, and Pluto (http://occult.mit.edu). In the past, three strategies have been used for observation of occultations by small bodies, and each can be used for KBOs: (i) a network of portable telescopes (0.36 m), (ii) an airborne telescope (2.5 m for SOFIA), and (iii) large, fixed telescopes (6.5-10 m) that happen to lie within the occultation path. Each of these strategies has a limiting magnitude for events of sufficiently high S/N to achieve the observational objectives. For a sample of 29 KBOs (2003, March) with diameters larger than 600 km (based on an albedo of 0.04), we have estimated the annual rates of observable events (Earth, Moon, and Planets, in press) to be ~6 for portable telescopes, ~200 for SOFIA, and ~4 for Magellan. These rates will increase as more large KBOs are discovered. A comprehensive targeted occultation program will require a cooperative effort from the community to generate the predictions and carry out the observations. This work was supported, in part, by NASA Grant NAG5-10444.
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.