• Mcneill, Andrew
• Lilly, Eva
• Trilling, David E.
• Consortium, Members Of The Pan-Starrs Science
• Fitzsimmons, Alan
• Jedicke, Robert
• Lacerda, Pedro

Abstract

Using sparse photometry of main belt asteroids obtained in the first 1.5years of the Pan-STARRS 1 survey we identified a list of potential'extreme lightcurve asteroids', defined as objects witheither rotation period P <2.2 h or light curve amplitude A ≥ 1.0mag. Follow-up observations were made of 22 asteroids using the 2.5 mIsaac Newton Telescope, the 3.5m ESO New Technology Telescope and theUniversity of Hawaii 2.2 m Telescope. 9 of these objects were found tohave light curve amplitudes A > 1.0 mag, with no objects with P <2.2 h being observed. From lightcurve analysis we determine that 5 maybe single rubble pile ellipsoids with significant cohesive strength allowing them to resist mass shedding even at their highly elongatedshapes. It was not possible to analytically find unique shape solutionsfor the remaining objects with the available data. Two asteroids wereobserved at a number of orbital geometries allowing for shape and spinpole models to be determined through light curve inversion. (45864) 2000UO97 was determined to have retrograde rotation with spin pole latitudeand longitude β=82 ± 5⊙, λ=218± 10⊙ and asteroid (206167) 2002 TS242 was foundto have spin pole axes β=-67 ± 5⊙,λ= 57 ± 5⊙. Using serendipitousobservations, an additional asteroid not initially measured with A >1.0 mag, (49257) 1998 TJ31, was determined to have a shape modelsuggesting a higher amplitude than that measured from its sparsephotometry light curve (A = 0.8 mag). Its spin pole axes were found tobe β=6 ± 5⊙, λ=112 ±6⊙. The high obliquity of this object could explain howwe initially failed to identify this body as high amplitude from itslight curve alone, when its shape solution suggests otherwise. Since theinitial generation of our target list, the number of asteroid detectionsby Pan-STARRS has increased dramatically. Using the same criteria forthe generation of this initial target list but utilising all of the dataavailable we now have a list of 110 potential high amplitude objectswhich we are continuing to observe.

Topics

• strength