AO Psc: modeling 4 years of observations
Observed: 13, 14, 19 July, 18 Aug 2007 and 2004-2006
The synodic period Psyn is allowed to vary with time:
and the spin period Prot may be computed as:
The model function is fitted to the observations the following way:
The method works the following way:
For tsyn and trot, I start from the values I obtained in my modeling
of my 2004-2006 observations and for the ranges I use twice the uncertainties;
For P0syn I use the value I derived from the 2004-2005 interseason that has a smaller uncertainty than the value for 2004 observations:
P0syn = 858.6426 +/- 0.0050 s;
For the derivative of the period, I start from PPsyn=0 with a range of 10^-10;
For the other parameters, I also start from my 2004-2006 modeling and I estimate the ranges by hand.
Futhermore, AO Psc being brighter in 2007, I substract 0.15mag to the 2007 magnitudes.
AO Psc is found still spinning up with dP/dt=-(4.3+/2.3)*10^-11, comparable with Williams (2003).
Usually dP/dt is derived by the O-C analysis of the pulsations from observations spanning many years. I am able to detect the spinning up from a limited set of amateur observations owing to the modeling.
The resulting light curves and the model function:
Red: the observed magnitudes,
Brown: the H(t) model,
Blue: Hsyn(t)+A0 shifted by -0.2mag,
Gary B. (2007) Exoplanet observing for amateurs Reductionist Publications.
(May be downloaded from http://brucegary.net/book_EOA/x.htm.)
Kaluzny J., Semeniuk I. (1988) IBVS 3145.
Williams G. (2003) PASP 115 618.
2004 AO Psc observations, with the sorting out of the synodic and of the spin oscillations.
2005 AO Psc observations.
2006 AO Psc observations, with a O-C analysis of the 2004-2006 pulsations, that favors the Fit 1 of Williams (2003).
A similar modeling was done for FO Aqr with 2004-2007 observations, and it was also found spinning up.
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