Let the two tables OBSERVA.tbl and OBSERVB.tbl contain two sets of observations. Each set is stored in the DOUBLE PRECISION columns :TIME, :VALUE and :VAR containing the times of observation, data value and their variances.
CREATE/GRAPHICS ! Create graphics window
SET/CONTEXT TSA ! Enable TSA package
NORMALIZE/TSA OBSERVA :VALUE V ! Normalize variance in both light
NORMALIZE/TSA OBSERVB :VALUE V ! curves to the same value of 1
COVAR/TSA OBSERVA OBSERVA AUTOCOVA 1. 0.1 24 LOG
Compute autocov. of `A'
PLOT/TAB AUTOCOVA :LAG :COVAR ! Plot autocov. function of `A'
COVAR/TSA OBSERVB OBSERVB AUTOCOVB ? ? ? LOG
Compute autocov. of `B'
PLOT/TAB AUTOCOVB :LAG :COVAR ! Plot autocov. function of `B'
COVAR/TSA OBSERVA OBSERVB CROSSCOV ? ? ? LOG
Compute crosscov. of `A' and `B'
PLOT/TAB CROSSCOV :LAG :COVAR ! Plot crosscovariance function
! Now you have to fit a common analytic formula to both autocor-
! relation functions, AUTOCOVA and AUTOCOVBB. The MIDAS FIT package
! or any other suitable tool may be used for this purpose.
! Choose one of the predefined function forms or code your own
! function URi, 0 < i < 10, in FORTRAN. Then, the analysis
! of the delay can proceed:
DELAY/TSA OBSERVA OBSERVB CHI2LAG 0 5 200 EXP 0,1,-0.25
! Do Chi2-time lag analysis
PLOT/TAB CHI2LAG :LAG :CHI2 ! Plot the results
Abramovitz, M. & Stegun, I.A.: 1972, Handbook of Mathematical Functions, Dover, New York.
Acton, F.S.: 1970, Numerical Methods that Work, Harper & Row, New York.
Bloomfield, P.: 1976, Fourier Analysis of Time Series: An Introduction, Wiley, New York.
Brandt, S.: 1970, Statistical and computational methods in data analysis, North Holland, Amsterdam.
Chatfield, C.: 1985, The Analysis of Time Series: An Introduction, Chapman & Hall, London.
Deeming, T.J.: 1975, Astron. Astrophys. Suppl. 36, 137.
Dvoretsky, M.M.: 1983, Mon. Not. R. astr. Soc. 203, 917.
Eadie, W.T., Drijard, D., James, F.E., Roos, M. & Sadoulet, B.: 1971, Statistical methods in experimental physics, NorthHolland, Amsterdam.
Edelson, R.A. & Krolik J.H.: 1988, Astrophys. J. 333, 646.
Gray, D.F. & Desikachary, K.: 1973, Astrophys. J. 181, 523.
Lafler, J. & Kinman, T.D.: 1965, Astrophys. J. Suppl. 11, 216.
Lomb, N.R.: 1976, Astrophys. Space Sci. 39, 447.
MIDAS Users Guide: 1992 November, European Southern Observatory, Garching.
Press, W.H., Flannery, B.P, Teukolsky, S.A. & Vetterling, W.T.: 1986, Numerical Recipes, Cambridge University Press, Cambridge.
Press, W.H. & Rybicki, G.B.: 1989, Astrophys. J. 338, 277.
Press, W.H. et al.: 1992, Astrophys. J. 385, 404.
Renson, P.: 1978, Astron. Astroph. 63, 125.
Roberts, D.H. et al.: 1987, Astron. J. 93, 968.
Scargle, J.H.: 1982, Astrophys. J. 263, 835.
Schwarzenberg-Czerny, A.: 1989, Mon. Not. R. astr. Soc. 241, 153.
Schwarzenberg-Czerny, A.: 1991, Mon. Not. R. astr. Soc. 253, 198.
Schwarzenberg-Czerny, A.: 1996, Astrophys. J. 460, L107.
Stellingwerf, R.F.: 1978, Astrophys. J. 224, 953.
=31 =1 =1993