In responce to Victor Ruiz's request for info on period determination
methods for variable stars, I compiled my 2 cents worth...

An old but nice introduction and review to the four or five most popular
period finding methods can be found in [1] by Fullerton.  
This includes the various "string-length" methods made popular by 
Lafler and Kinman [2].  This method has been expanded upon by 
Stellingwerf [3] with the PDM method which is now a part of IRAF.  
Most of the people I am associated with use FFT methods as prescibed by 
Horne and Baliunas [4] and can now be found in the Numerical Recipes [5] book.
There is also a DFT method [6] which I am not too familiar with.

I am also interested in anyone else's methods and ideas...

References:
1. The Study of Variable Stars Using Small Telescopes, Fullerton, A.W. 1986,
   ed. J.R. Percy, Cambridge University Press, p 201-218.

2. An RR Lyrae Survey With The Lick 20-inch Astrograph II. The Calculation
   of RR Lyrae Periods By Electronic Computer, Lafler, J. and Kinman, T.D.
   ApJS 11, p 216-222.

3. Period Determination Using Phase Dispersion Minimization (PDM), 
   Stellingwerf, R.F. 1978, ApJ 224, 953-960.

4. A Prescription for Period Analysis of Unevenly Sampled Time Series,
   Horne, J. and Baliunas, S. 1986, ApJ 302, 757-763.

5. Search Algorithm For Weak Periodic Signals In Unevenly Spaced Time-Series,
   Press, W.H. and Teukolsky, S.A., Numerical Recipes, Cambridge Univ. Press.

6. Roberts, 1987, AJ 93, 968
   Grindlay, 1988, ApJ, 334, L25
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	Jeff W. Robertson	       Improvise, Adapt, Overcome...Iterate.
	Indiana University Astronomy
	bigjay@astro.indiana.edu	                   
	http://www.astro.indiana.edu/~bigjay
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