TREMENDOUS OUTBURST AMPLITUDE DWARF NOVAE

For many years, observers have noted the existence of a number of trem endous outburst amplitude dwarf novae. We present a summary of the kno wn observational parameters for these exceptional systems. They show o utburst amplitudes of 6-10 mag, have rare outbursts (interoutburst tim es being months to decades), and only seem to exist in dwarf novae wit h short orbital periods. We calculate new accretion disk models which can reproduce their outburst behavior very well. It appears that these dwarf novae have low mass transfer rates at minimum, and the viscosit y during quiescence is about 10 times smaller than for other dwarf nov ae. Their relation to SU UMa stars is discussed.