Photometry results of 32 asteroids are reported from only seven observing
nights on only seven fields, consisting of 34.11 cumulative hours of
observations. The data were obtained with a wide-field CCD (40.5'x27.3')
mounted on a small, 46-cm telescope at the Wise Observatory. The fields are
located within 1.5 degrees from the ecliptic plane and include a region within
the main asteroid belt. The observed fields show a projected density of ~23.7
asteroids per square degree to the limit of our observations. 13 of the
lightcurves were successfully analyzed to derive the asteroids' spin periods.
These range from 2.37 up to 20.2 hours with a median value of 3.7 hours. 11 of
these objects have diameters in order of two km and less, a size range that
until recently has not been photometrically studied. The results obtained
during this short observing run emphasize the efficiency of wide-field CCD
photometry of asteroids, which is necessary to improve spin statistics and
understand spin evolution processes. We added our derived spin periods to data
from the literature and compared the spin rate distributions of small main belt
asteroids (5>D>0.15 km) with that of bigger asteroids and of similar-sized
NEAs. We found that the small MBAs do not show the clear Maxwellian-shaped
distribution as large asteroids do; rather they have a spin rate distribution
similar to that of NEAs. This implies that non-Maxwellian spin rate
distribution is controlled by the asteroids' sizes rather than their locations.Comment: 46 pages, 27 figures, 6 tables, accepted for publication in Icaru