[Previous] | [Session 16] | [Next]
D. L. Rabinowitz, M. D. Hicks (JPL/Caltech)
Since August of 1996, we have used the 24" telescope at Table Mountain Observatory (Wrightwood CA) to make photometric observations (B, V, R, and I filters + CCD) of more than 100 near-Earth and Mars-crossing asteroids [1]. Owing to frequent access to the telescope (5 to 10 nights per month), we have observed most of our targets close to their discovery dates, when they have been their brightest. Such opportunities have also increased in frequency owing to several new search programs (JPL's NEAT program [2] and MIT/Lincoln Labs LINEAR program) that have broad sky coverage (> 500 sq. deg. per night) and bright limiting magnitudes (V<19). About half of our targets have sizes in the range 10 m to 1 km, significantly smaller than the targets of previous surveys [3,4]. Ongoing analysis of the reflectance colors of these objects support our previous conclusion that the colors are size dependent. This has also been confirmed by recent spectroscopic observations of larger NEOs and main-belt asteroids [5].
[1] Rabinowitz, D. L. 1998. Size and orbit dependent trends in the reflectance colors of Earth-approaching asteroids. Icarus, in press; [2] Helin et al. 1998. Results of the JPL near-Earth asteroid tracking (NEAT) program. This proceedings; [3] Binzel, et al. 1996. Spectral properties of near-Earth asteroids: evidence for sources of ordinary chondrite meteorites. Science 273, 946; [4] Hicks, M. et al. 1998. The unusual spectra of 15 near-Earth asteroids and extinct comet candidates. Icarus 133, 69; [5] Binzel, et al. 1998. Size dependence of asteroid spectral properties: SMASS results for near-Earth and main-belt asteroids. LPSC 29.