Strömgren Photometry of C/1995 O1 in March 1997. Short-Term Variability

J. L. Ortiz, E. Rodríguez, M. J. López-González, A. Rolland, M. A. Hobart, E. Sánchez-Blanco, P. J. Gutiérrez, J. J. López-Moreno (Instituto de Astrofísica de Andalucía, CSIC)

We present uvby Strömgren photometry of comet C/1995 O1 Hale-Bopp, obtained during nearly three weeks in March 1997. The Fourier transform method has been used to analyse the periodicities present in the light curves. We have found two different periodicities: a long period of 7.19 days and a shorter one of 5.5 hours. The 5.5-hour periodicity may correspond to a full rotation of 11 hours whereas the 7.19-day periodicity could be related to the precession period. We discuss these results in terms of complex rotation of the nucleus.