  A class of asteroids, called large super-fast rotators (large SFRs), have
rotation periods shorter than 2 hours and diameters larger than ~ 0.3 km. They
pose challenges to the usual interior rubble-pile structure unless a relatively
high bulk density is assumed. So far, only six large SFRs have been found.
Therefore, we present a survey of asteroid rotation period using Pan-STARRS 1
telescopes during 2016 October 26 to 31 to search more large SFRs and study
their properties. A total of 876 reliable rotation periods are measured, among
which seven are large SFRs, thereby increasing the inventory of known large
SFRs. These seven newly discovered large SFRs have diverse colors and locations
in the main asteroid belt, suggesting that the taxonomic tendency and the
location preference in the inner main belt of the six perviously known large
SFRs could be a bias due to various observational limits. Interestingly, five
out of the seven newly discovered large SFRs are mid main-belt asteroids.
Considering the rare discovery rates of large SFR in the previously similar
surveys (Chang et al., 2015, 2016) and the survey condition in this work, the
chance of detecting a large SFR in the inner main belt seems to be relatively
low. This probably suggests that the inner main belt harbors less large SFRs
than the mid main belt. From our survey, we also found the drop in number
appearing at f > 5 rev/day on the spin-rate distribution for the outer
main-belt asteroids of D < 3 km, which was reported for the inner and mid main
belt by (Chang et al., 2015, 2016).
