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2014 Pan-STARRS1

Magnitudes, Phase Functions and Spin Statistics of Asteroids from PS1

Presented by: Alan Fitzsimmons  (Queen's University Belfast)
Category: Science Workshops   Duration: 15 minutes   Broadcast date: June 23, 2014
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During the PS1 surveys the IPP+MOPS pipeline has resulted in the identification of more than 7 million moving objects. The vast majority of these were main-belt asteroids. The excellent photometry available has allowed us to calculate absolute magnitudes and phase functions for a subset of ~240,000 asteroids (Veres et al, in preparation), using both the original IAU (H,G) system of Bowell et al. (1989) and the new (H,G12) system of Muinonen et al. (2010). As found by previous authors, the true absolute magnitudes are systematically fainter than current catalogues at H>16. We will present our current understanding of the biases inherent in previous studies relative to the absolute photometry from PS1. The sparse sampling present in the current PS1 catalogue prevents lightcurve solutions for most main-belt asteroids. Therefore we have measured the observed cumulative-frequency distribution of the magnitude differences present within tracklet pairs of observations. We find strong evidence of YORP-induced spin pole alignments at larger diameters. This grows weaker going down towards 1 km radius, which may imply a growing tendency for non-principal axis rotations due to collisions (McNeill et al., in preparation).

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Alan Fitzsimmons' slides PDF document (.pdf)