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Abstract: We present the results of our Thousand Asteroid Light Curve Survey TALCSconducted with the Canada-France-Hawaii Telescope in September 2006. Ouruntargeted survey detected 828 Main Belt asteroids to a limiting magnitude ofg-~22.5 corresponding to a diameter range of 0.4 km <= D <= 10 km. Of these,278 objects had photometry of sufficient quality to perform rotation periodfits. We debiased the observations and light curve fitting process to determinethe true distribution of rotation periods and light curve amplitudes of MainBelt asteroids. We confirm a previously reported excess in the fraction of fastrotators but find a much larger excess of slow rotating asteroids ~15% of oursample. A few percent of objects in the TALCS size range have large lightcurve amplitudes of ~1 mag. Fits to the debiased distribution of light curveamplitudes indicate that the distribution of triaxial ellipsoid asteroid shapesis proportional to the square of the axis-ratio, b-a^2, and may be bi-modal.Finally, we find six objects with rotation periods that may be less than 2hours with diameters between 400 m and 1.5 km, well above the break-up limitfor a gravitationally-bound aggregate. Our debiased data indicate that thispopulation represents <4% of the Main Belt in the 1-10 km size range.

Author: Joseph Masiero IfA, Hawaii, Robert Jedicke IfA, Hawaii, Josef Durech Ast. Inst., Charles Univ., Prague, Stephen Gwyn CADC, Larry


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