Results of cooperative optical observations of EV Lac in September 1991 are presented. During 50 hours of photoelectric monitoring more than 40 flares were detected, including several events of moderate power and one very strong flare with amplitude {DELTA}U=3.7mag and duration of about half hour. Detailed colour analysis of this strong flare

Not Available

Not Available

Not Available

The magnetic flux tubes that rise across the convection zone to produce active regions are shown to develop a difference in inclination between their preceding and follower sides. This asymmetry is such that the following wing is more vertical (i.e., closer to the radial direction) than the preceding side. An asymmetry of this kind can be obtained

We present the B-band surface photometry of 19 early-type galaxies of the Virgo cluster, and of 28 galaxies of the same morphological type belonging to the Fornax clusters, obtained through the `global mapping' technique which couples CCD and photographic plates. Taking into account 33 galaxies already studied by Caon et al. (1990) with the same