PublisherThe University of Arizona.
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AbstractFourteen models were constructed and observed in the laboratory for light variation at different orientations of the rotation axis relative to the detector and the light source. In all, 311 lightcurves were obtained for elongated models with fairly uniform surface reflectivities. While there are some lightcurve features that may be used to distinguish between differences in the shape of the models, it is necessary first to know the position of the rotation axis with good precision (up to ± 1° for highly elongated bodies). In general, there is no amplitude- aspect function characteristic of each model, but approximate relations may be used if the phase angles are <20° and if the maximum lightcurve amplitude is ≥ 0 ͫ.4. The model data are compared to the observations of Hektor and Geographos and suggest that Hektor may be a double body, and that Geographos is about three times longer than it is wide. Shifts in the arrival times of the lightcurve maxima of one of the models were used to obtain the orientation of the rotation axis and sidereal period of Geographos. An equation for this time shift, which agrees with most of the model observations, is given and should be used in correcting epochs of maximum light in lightcurves of elongated asteroids.
Degree ProgramGraduate College