ST ScI Preprint #1363 . ... A maximum UV variation of ~ 50% is detected, while during the same period the X-ray flux varied by no more than 13%. ... 2) Present address: Istituto di Tecnologie e Studio delle Radiazioni Extraterrestri, CNR, Via Gobetti 101, I-40129 Bologna, Italy . ... 7) Department of Physics, University of Como, Via Lucini 3, I-22100 Como, Italy . 8) Istituto di Fisica Cosmica e Tecnologie Relative, CNR, via Bassini 15, I-20133 Milan, Italy . ...