Dear readers, This is very interesting! Nova Sgr 1998 is most probably a permanent superhump system (Lipkin, personal communication). Thus, it cannot have dwarf nova outbursts. Short-term outbursts have been observed in a few systems (TV Col, AM CVn, and even once in Nova V705 Cas 1993). To explain this behaviour, I prefer the idea of Hellier and Buckley (1993), who suggested that these mini-outbursts are mass transfer events. However, other explanations are possible (e.g. magnetic activities as in our sun...). I, therefore, suspect that the nova will return back to its 'quiescence' state (the level before this event, not the nova event) very fast. If I am wrong, though, and this would be a long dwarf nova like outburst, it should pose serious difficulties to the Disc-Instability model. Observers are encouraged to confirm this result, and to check the current magnitude of the nova. Regards, Alon ------------------------------------------------------------------------- Dr. Alon Retter Tel. (work) +44-(0)1782-58-3493 Physics Dept. Fax (work) +44-(0)1782-711093 Keele University ----------------------------------- Staffordshire 'As a scientist I don't believe myself, so ST5 5BG, U.K. why should I believe you?' (A.R. 1965-2085) ------------------------------------------------------------------------- On Mon, 13 Sep 1999, Taichi Kato wrote: > Nova Sgr 1998 brightening! > > T. Watanabe reports a considerable brightening of Nova Sgr 1998. > > YYMMDD(UT) mag observer > 990818.517 14.04Rc (S. Kiyota) > 990818.521 13.53V (S. Kiyota) > 990818.528 14.16B (S. Kiyota) > 990828.719 132 (B. Monard) > 990831.531 139 (T. Watanabe) > 990905.497 14.18Rc (S. Kiyota) > 990905.500 15.32V (S. Kiyota) > 990912.507 130 (T. Watanabe) > >