OBSERVATION OF SMALL FLARES AND A LONG-LASTING PREFLARE DIP ON V-1054-OPHIUCHI

We report on the observations and analysis of two small flares and of an exceptionally long pre-flare dip observed on V 1054 Oph by a twin-b eam UBV photometer that permit to reach high photometric precision, Th e monitoring of V 1054 Oph has been carried out as part of a project m ainly devoted to the detection of low amplitude optical variability an d microflares in very active red dwarf flare stars. We discuss our res ults in the framework of present theories on stellar flares and pre-fl are dips, including the particularly severe constraints that the prese nt results - and previous observations of pre-flare dips on FF And - p ose on the most relevant flare models.