[vsnet-chat 122] Determining times of minima or maxima

[Roland.Boninsegna@gate71.be (Roland Boninsegna)]

Dear observers of periodical stars,


Concerning the determination of the eclipsing binaries minima, I would like
to add that several kinds of software are used in our group GEOS. Some are
based on least square methods, some other on cubic spline functions, some
others developped by Adriano Gaspani on neural network or stochastic
optimization. Almost all these softwares worked properly IF used properly.
Do never forget to stay open-minded and to let your eyes be the referee of
your reduction, not the computer.

One good method for these reductions is the so called "tracing paper
method", which applied by several people for each minimum yield a secure
time of minimum, not less accurate than computers offer. I always recommend
that method for new observers: it is important that they can reduce their
own observation by themselves.

For assymetric eclipsing curves (quite rare) or maxima of pulsating stars,
the cubic spline functions work well also and let you with some freedom to
adjust your curve as  you prefer. The success of the Pogson method will
strongly be dependant of the quality of your observation. Some time a simple
determination "by eye" will be
faster and not so bad.

Best regards                                    Roland

Roland Boninsegna				Asteroidal Occultations (EAON)
Rue de Mariembourg, 35		Observations of Suspected Variable Stars (GEOS)	
B  5670  Dourbes				Astronomy teaching (EAAE)
Tel: + 32 60 399925			E-mail: roland.boninsegna@gate71.be

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