SHORT-TERM VARIABILITY IN COMET C 1995 O1 HALE-BOPP/

Simultaneous uvby Stromgren photometric observations of the comet Hale -Bopp have been collected during nearly three weeks. The Fourier trans form method has been used to analyse the periodicities in luminosity p resent in this comet. Two different periodicities have been found: a l ong period of 7.19 days and a shorter one of 5.5 hours. The 5.5-hour p eriodicity may correspond to a full rotation of 11 hours whereas the 7 .19-day periodicity could be related with the precession period. Other possibilities are discussed.