Dear Berto, Taichi and others, If the oscillation in Nova Cir 1999 are real or not: I just want to note that Nova V1668 Cyg 1978 had a similar behaviour. A periodicity of ~13 hours was discovered in its early stages, and was interpreted as oscillations in the common envelope surrounding the binary system. It is very different from the orbital period of ~3 h discovered later. To my knowledge, it has never been observed in any other novae. 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 Thu, 2 Sep 1999, Berto Monard wrote: > Dear Taichi and readers, > > I would like to comment on the posting from Brian Fraser. > > There is a definite possibility of magnitude estimate off-sets due to > personal differences in red/blue sensitivity and perhaps here and > there some personal bias regarding to what possibly is the expected > magnitude of the nova at that moment. > However I disagree that this should be generalised and that I > therefore wish to state my agreement with Taichi's statement that the > oscillations are a true representation of the nova's past behaviour. I > have no doubt that the nova has been down to (at least) around > magnitude 8.7 on 24/8 (as reported by experienced observers) and that > it re-brightened afterwards and reported 12 hours later at around 8.0 > by experienced observers from other continents. This oscillation has > repeated itself with a diminishing amplitude during the following 24 h > as seen in the lightcurve by experienced observers. > There is no doubt in my mind that a (probably aperiodic) oscillation > in the luminosity of Nova Cir 1999 took place. > > Best regards, > > Berto Monard > Pretoria > > >>> Taichi Kato <tkato@kusastro.kyoto-u.ac.jp> 09/02 10:40 AM >>> > >From brian.fraser@Macsteel.co.za Thu Sep 2 15:25 JST 1999 > From: "brian.fraser" <brian.fraser@Macsteel.co.za> > To: Taichi Kato <tkato@kusastro.kyoto-u.ac.jp> > Subject: RE: [vsnet-chat 2273] Strong oscillation in Nova Cir 1999? > Date: Thu, 2 Sep 1999 08:14:47 +0200 > MIME-Version: 1.0 > Content-Type: text/plain > Content-Length: 1428 > > Hello Taichi, > I was thinking about this topic when I came upon this possible > explanation. > It looks to me as though each observer has his "personal bias" ie when > he is > in doubt he goes for a lower estimate or maybe a higher estimate. > So you are looking at the results from one or two observers in > Australia, > one or two in South America, some in South Africa. If an active > observer in > Australia is consistently over-estimating the magnitude (just by 0.1 > or 0.2) > and an observer in South Africa is consistently under-estimating, it > could > quite easily look as though there was a one day cycle. Maybe this is > what > is happening?? > Just a thought, > regards, > Brian Fraser > > ======================================================= > Trust in God but lock your car. > > Brian Fraser > Tel 27 11 871-0370 > Fax 27 11 871-0226 > email brian.fraser@macsteel.co.za > > > > -----Original Message----- > > From: Taichi Kato [SMTP:tkato@kusastro.kyoto-u.ac.jp] > > Sent: Wednesday, September 01, 1999 4:41 PM > > To: vsnet-chat@kusastro.kyoto-u.ac.jp > > Subject: [vsnet-chat 2273] Strong oscillation in Nova Cir 1999? > > > > Strong oscillation in Nova Cir 1999? > > > > Upon examination of the reported data, I have noticed the nova > may be > > oscillating with a period close to 1 d. On Aug. 24 and 25, the nova > > faded by nearly 1 mag within 12 hours, and recovered (not well > covered > > by observations). Has anyone noticed this phenomenon? > > > > Regards, > > Taichi Kato > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >