Super-fast rotators (SFRs; P < 2.2 hr) are of great importance in asteroid studies; yet, many reported detections suffer from aliasing caused by an insufficient observation cadence. We present dense CCD photometry for 15 SFRs candidates (14 after excluding 11219 Benbohn, whose published period already exceeds the spin barrier) observed from 2023 Aug 11 to 2024 Aug 11 with the 1.5 m Sierra Nevada and 1.4 m AS Vidojevica telescopes. Our dataset comprises approximately 2,400 calibrated data points, with per-measurement formal errors of 0.02-0.04 mag and total on-target coverage of 2-13 hr per object. We have reliably determined periods for 9 targets. In terms of spin rate, we have confirmed four SFRs with periods of 1.06-1.84 hr and peak-to-peak amplitudes of 0.054-0.685 mag. Three candidates remain ambiguous, while the rest are reclassified, showing the best solutions with periods greater than 2.5 hr. By extrapolating from our confirmation rate (4/14) to the 3.9 percent occurrence rate found in the Light Curve Database (LCDB) yields a central SFR fraction of 1.1 percent, with a one-sigma lower bound of 0.6 percent among kilometre-scale asteroids.
Novaković et al. (Mon,) studied this question.