The rubble-pile model of asteroids deduced from the existence of a spin cutoff is an important paradigm in the interior structure of asteroids as a consequence of their collisional evolution. Many objects with size less than 200 m have been found to be rotating with a spin period less than 2.2 h but seldom so for bigger objects. Thus, as-teroids with rotation periods significantly less than this spin cutoff limit are called super-fast rotators. Most often this picture of spin cutoff and hence the rubble-pile model has been applied to the S-type asteroids. In this study, we report the interesting case of (3599) Basov which is a member of the Themis family of C-class composition. The spin barrier of the Themis family asteroids has been shown to be P = 3 h. What is unusual about (3599) Basov is that its rotation period has been confirmed to be P = 2.157 +/- 0.037 h which is significantly shorter than the critical value for centrifugal breakup. Furthermore, its size of 18 km is much larger than those of the S-class super-fast rotators. The physical property of (3599) Basov might therefore be quite unique.
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