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From John Greaves: Taichi Kato wrote : > Do you really think that this classification scheme is still valid? > NA is simply a "fast nova" and NB a "slow nova". The borderline of > classification depends on authors (very subjective!). I don't think > it very meaningful to correlate this classification with parameters > such as T2 or T3. It's inclusion was primarily a consequence of retaining the structure of the Duerbeck list which was used for the vast majority of the pre 1987 data. It's nice to know whether a nova was fast or slow. I think I was even going to see if small regions preferentially provided one type or another at one point, though I never did (some parts of Aquila, for example, have been nova rich). However, a classification based on _eventual_ lightcurve would be much nicer, and more in keeping with other variable classification, and to some extent suprenova classification, schemes. There'd be fast lightcurves, slow lightcurves and oscillating lightcurves at least, I think, possibly not much use for anything extra. I'm a bit rusty on my novae reading, though. Most formal schemes seem to be spectroscopically based. In the case of cataclysmic variables, spectroscopic classifications and lightcurve classifications (in for example 'novalike' CVs) tend to overlap a lot, with GK Per being my favourite example of a multiclassified DN, UG, NC, IP/DQHER, and propably others, object, depending on how you look at it, and this may well be the case in novae too, for all I know. Of course, using a slightly extended lightcurve criterion you could, as Bill Liller suggests, bring NR in easier, and possibly even NX (or however xray novae are annotated) at a pinch. Duerbeck seems to have been of a generation to be still "old school" in his approach to the matter, and his teams' work seems to have taken Cecilia Payne- Gaposchkin's seminal (1905s???) work on novae classification as a guide. Since Duerbeck, spectroscopic appraisal seems to be to the fore, but of course this is no use for past novae. Whether there's a professional around nowadays how could get hold of sufficient data to generate lightcurves, I do not know. Indeed, use of T2 and/or T3 is probably an attempt to get around the sparsity of data for many past novae. Cheers John John Greaves PS re GU Mus and V518 Per and historical reasons: wasn't ROSAT working then? Maybe they called for visual confirmations, thinking they'd detected xray signatures of novae, whilst in effect these were not quite classical novae, at least in optical terms? There certainly appears to have been a window of xray novae discoveries suggesting a connection with a satellite campaign.
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