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Other than collisional, YORP is the only effect that will dampen an asteroids spin rate. Current thinking is that YORP affects asteroids on the inverse square of their size and the inverse square of their semi major axis. The 1332 hr target is not less than 83km (spectrally a C type but measured albedo is considered too high for a C type so the diameter measurement is a limiting minimum) and an outer main belt asteroid and as a slow rotator "challenges" the current paradym!
Given the current understanding of the formation of asteroids, significant non uniform distribution is unlikely, even in a contact binary case.
If the objects spin rate was artificially reduced by collision, one would expect tumbling as a result. However, for an object large enough to cause the spin rate to reduce significantly one would expect a large impact crater and with a large crater one would also expect a large amplitude in the lightcurve. This target has only shown amplitudes of 0.02 to 0.14mag in 5 sets of observations since 2000 by 4 different observers. Previous observations were less than complete generating periods from 6 to 48 hrs with low reliability.
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