THE TIME SCALES OF THE OPTICAL VARIABILITY OF BLAZARS .4. OI 090.4

Optical photometric observations of the blazar OI 090.4 are presented as part of an ongoing study of variations in blazars occurring on time scales of minutes to hours, which has been termed microvariability. T he observations presented here reveal the existence of such variabilit y for this blazar and provide further evidence of the class-wide natur e of this phenomenon. Time scales as short as these provide important clues about the nature of blazars, and a discussion of the types of po ssible mechanisms responsible for producing these variations is given. (C) 1997 American Astronomical Society.