Multi-colour optical monitoring of the intra-day variable blazar S5 0716+71

We report multi-colour optical monitoring of the intra-day variable blazar S5 0716+71 with a dense temporal coverage over a total duration of 4 weeks in February/March 1994. Four filters (BV Johnson and RI Cousins) were used on a majority of the nights. The light curves of the blazar were derived re lative to two comparison stars present on the CCD frames. Intensity variati ons of greater than or equal to 0.05 mag from night-to-night were observed in half the cases and a good correlation between the light curves in the di fferent passbands was noticed (as also for the observed intra-night variati ons). There seems to be no correlation between flux and optical spectral in dex of the blazar. In all, three prominent events of intra-night variabilit y were detected, each with a rate of greater than or equal to 0.1 mag per h our, lasting for at least 3 hours. Each of these flaring segments of the bl azar light curves can be well fitted with an exponential intensity profile whose rate of variation is essentially the same for all the passbands. No c lear event of ultra-rapid fluctuations of the blazar on time scale less tha n or equal to 1 hour was detected in these multi-colour data. Present obser vations have been carried out during a low brightness level of the blazer a nd they have no large amplitude variable events.