Hi Peter and Sebastian, A long time ago Harry Williams and I measured this star for a time. The results are in the attached file - all 14 UBV measures! These tend to suggest that the variation is from 5.0 to 5.8 at least. I did a periodogram of this and found a main period of 98.8 days although the data didn't fit this all too well. I see the GCVS gave 119 days and a range of 6.4-8.6p. I've also appended details of our comparison and check, V,B-V,U-B. I'm uncertain where the check values came from but the comparison would be good. Theta Aps is obviously not a Mira with this type of period and amplitude although the GCVS spectral type of M7III doesn't look much like an SR star. This spectral type is probably incorrect. We concluded that it probably had two periods which beat together. Unfortunately the pe data was not extensive enough to check this. But the departures from a simple curve in what we have are very significant. I'd imagine that Sebastian has measures during an interval when the beat period is low, or has reinforced one or two bright maxima. I didn't see him quote a period and haven't had time to get onto the website. The variable amplitudes quoted by Peter support the idea of dual periods and I would have expected these to show up in a DFT analysis. There's a nice number of measures for sampling there. It also appears that the VSS sequence is not exact but this is not a real problem except when you're trying to compare maxima or amplitudes. I think that this maybe emphasises that the old-fashioned way of describing periods is no longer adequate. A good example of this is L2 Puppis where there are about 4 periods, with the main period of ~140 days beating with a strong secondary period of ~100 days. But there are times also when the amplitude becomes much lower than this simple approach justifies. So a paper about an SR star identifying only one period confuses more than it explains - even if this is what the VSS seems to like. Regards, Stan COMP",14,08.7,-74,51, 6.02,0.58,0.1 CHECK",14,17.1,-77,40.9, 7.7,1.1,1 ----- Original Message ----- From: Peter F Williams <pfwilliams@onaustralia.com.au> To: Sebastian Otero <varsao@fullzero.com.ar>; vsnet-chat <vsnet-chat@kusastro.kyoto-u.ac.jp>; <vsnet-gcvs@kusastro.kyoto-u.ac.jp> Sent: Monday, March 25, 2002 10:40 PM Subject: [vsnet-gcvs 201] Re: theta Apodis > > > Dear Sebastian and All, > > Re Theta Aps, appearing in Publications No24 of the VSS RASNZ (April 2000) > is a paper I prepared based on 553 visual observations between 1959 and > 1999 from the VSS data base. These indicated a mean visual range of 5.6 to > 6.4 and extremes of 5.2 to 6.8. An average period of 115.93 days was > found. Derived elements for maximum are JD 2449558 +/- 115.93 days. > > Reagrds > > Peter Williams > Heathcote NSW > > > > ---------- > From: Sebastian Otero <varsao@fullzero.com.ar> > To: vsnet-chat <vsnet-chat@kusastro.kyoto-u.ac.jp>; > vsnet-gcvs@kusastro.kyoto-u.ac.jp > Subject: [vsnet-gcvs 200] RX Leporis and theta Apodis > Date: Monday, 25 March 2002 2:38 > > RX Leporis period in the GCVS is wrong. The star has shown one of the most > stable periods of my program stars. > This one is close to 97 days. > You can see my lightcurve and data at: > http://ar.geocities.com/varsao/Curva_RX_Lep.htm > > Also theta Apodis is a very regular star in period and also in the > amplitude > of every cycle: the observed range is 5.0 - 6.1 (V). > http://ar.geocities.com/varsao/Curva_The_Aps.htm > > Regards, > Sebastian. > > > --- > Outgoing mail is certified Virus Free. > Checked by AVG anti-virus system (http://vsnet.grisoft.com). > Version: 6.0.325 / Virus Database: 182 - Release Date: 20/02/02
Thetaaps.ubv
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