THE ROTATION PERIOD OF C 1995 O1 (HALE-BOPP)

C/1995 O1 (Hale-Bopp) was observed in daylight on 16 days between 1997 April 1 and 1997 April 28, five of which had long time sequences (up to 10 hr of data), using the near infrared CAIN camera on the 1.5 m Ca rlos Sanchez Telescope at Teide Observatory (Tenerife, Canary Islands, Spain). Three spiral dust jet structures were observed for several al most complete rotations. A nucleus rotation period of 11.34 +/- 0.02 h r was determined from two different methods. No variations of the rota tion period with time due to precessional effects were found in our da ta. However, the time sampling of the observations, similar to the sug gested spin precession period, prevents us from ascertaining whether s uch variations exist. We note, though, that the good agreement of our results with the rotation periods at different epochs reported by othe r groups suggests that if they exist, these variations must be small, hence the rotation cannot be very complex.