The optical behaviour of ON 231 (W Comae) during and after the great outburst of spring 1998 G. Tosti, E. Massaro, R. Nesci, S. Ciprini, G. Nucciarelli, M. Maesano, F. Montagni, C. M. Raiteri, M. Villata, L. Lanteri and L. Ostorero A&A, 395 1 (2002) 11-15 Published online: 29 October 2002 DOI: 10.1051/0004-6361:20021209