[vsnet-chat 3765] RE: Delta Cep period analysis of visual observations

["Eric Broens" <Eric.Broens@advalvas.be>]

Dear Taichi,

I can confirm your findings.
a few years ago I analysed the raw visual observations of BL Her made by
observers of the Belgian VVS variable star section during the 80's. BL Her
is a CWB star varying between magnitude 9.7V and 10.62V. In the literature I
found periods ranging from 1.307443 d - 1.3074604 d.
The phase diagram of the raw data looked really bad, but using PDM, I found
a period of 1.307454! I didn't clean up the dataset for bad observations. I
don't have all the details of the analysis at hand (just a slide summarising
the result), but I remember the analysis was done on a few hundred
observations spanning years, but with quite long interuptions in between.
The nice thing besides the very well matched period was that all alias
periods one can expect were shown and the periodogram showed very clearly
1.00273 c/d, the 23h56m4s sidereal rotation period!

If one has a sufficient number of observations over a long time, one can get
extremely good results, even if the observations are not that accurate!

Best Regards,
Eric


************************************
VVS Werkgroep Veranderlijke Sterren

Eric Broens
Wateringstraat 143
B-2400 Mol
BELGIUM

e-mail: Eric.Broens@advalvas.be
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