Re: GSC 748-1618 period

[BARTHOLDI Paul <Paul.Bartholdi@obs.unige.ch>]

Dear Michael,

I guess your problem comes from the following. Your recent data come from a
small interval, and the frequency, even the "best" is not so precise. 
When you "extrapolate" you fit to data taken around 350 days earlier, that 
is around 450 period earlier, any small error in frequency make a significant
error in phase.

One other point could be important, during your computations, use times
to which t[0] has been first substracted. Rounding errors get soon very large
if you use the data as in the .txt file.

My best estimate, using Deeming fourier transform, gives f=0.777363 .
Though their is quite a lot of noise in the data, I can't see any significant 
not in phase ones.

Tonight, I will try my program with multiharmonics fitting and send you the 
results if they give any thing new.

Best regards,     Paul

    ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    +  Paul Bartholdi                 Paul.Bartholdi@obs.unige.ch  +
    +  Observatoire de Geneve    tel  +41 22 755 2611              +
    +  CH-1290 Sauverny          fax  +41 22 755 3983              +
    +  Switzerland               www  http://obswww.unige.ch/      +
    ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++