Asteroids' Size Distribution and Colors from HITS

Abstract

We report the observations of solar system objects during the 2015 campaign of the High cadence Transient Survey (HiTS). We found 5740 bodies (mostly Main Belt asteroids), 1203 of which were detected in different nights and in g ' and r '. Objects were linked in the barycenter system and their orbital parameters were computed assuming Keplerian motion. We identified 6 near Earth objects, 1738 Main Belt asteroids and 4 Trans-Neptunian objects. We did not find a g '-r ' color-size correlation for 14 H-g ' < 18 (1 D < 10 km) asteroids. We show asteroids' colors are disturbed by HiTS' 1.6 hr cadence and estimate that observations should be separated by at most 14 minutes to avoid confusion in future wide-field surveys like LSST. The size distribution for the Main Belt objects can be characterized as a simple power law with slope similar to 0.9, steeper than in any other survey, while data from the 2014 HiTS campaign has a distribution consistent with previous ones (slopes similar to 0.68 at the bright end and similar to 0.34 at the faint end). This difference is likely due to the ecliptic distribution of the Main Belt since the 2015 campaign surveyed farther from the ecliptic than did 2014's and most previous surveys.