AOV/TSA                                   15-SEPT-1992 A. Schwarzenberg-Czerny
    
Purpose:  
           Compute analysis-of-variance periodogramme. The expected value of 
           the periodogramme for pure noise is 1, for uncorrelated 
           observations and 'ncorr', for correlated observations,
           where 'ncorr' is an average number of correlated observations. The
           the periodogramme divided by its expected value has Fisher-Snedecor 
           probability distribution F(order-1,nobs/ncorr-1), where 'nobs' is
           number of observations and 'order' is defined below.
           For reference see M.N.R.A.S. 241, 153.
Syntax: 
           AOV/TSA intab outima start step nsteps [order] [cover]
           intab  = name of input table, it must contain columns :TIME and 
                    :VALUE in DOUBLE PRECISION. For numerical reasons it is 
                    advisable to subtract mean from :VALUE.
           outima = name of output image; its first row contains the AOV 
                    periodogramme, the second row contains quality flags 
                    indicating the quality of phase coverage for a given 
                    frequency. Meaning of the flags:
                    0 - all phases covered,
                    1 - underfilled phase bins occurred,
                    2 - empty bins occurred
                    Statistics of bad bins is listed onto terminal.
           start  = start frequency of the periodogramme, in inverse
                    units of :TIME 
           step   = frequency step of the periodogramme, in inverse
                    units of :TIME 
           nsteps = number of frequencies of the periodogramme
           order  = number of phase bins to be employed, 1 < order < 101.
           cover  = number of overlapping bin covers to be employed. Each
                    consecutive cover is shifted by 1/(order*cover) in phase.
                    0 < cover; default cover = 2.
See also:
           SHOW/TSA, DFT/TSA, SCARGLE/TSA
Note: 
           By default 'intab', 'outima', 'start', 'step', 'nsteps' and 'order' 
           retain their values from the last use of TSA commands, unless  
           explicitly specified. See SET/TSA for details of this feature.
           For smooth light curves use low 'order', e.g. 4 or 3 for best
           sensitivity. 
           For many observations and light curves with sharp
           features (e.g. pulses, eclipses) use phase bins of width 
           comparable to that of these features. This will boost
           sensitivity above that attainable with the Scargle method.
           Note that phase coverage at and near 0 frequency is notoriously
           poor for any observations. Hence underpopulated or empty
           bins may occurre. The summary statistics
           is printed onto the terminal and for details see the outima quality
           row. 
Examples:
           AOV/TSA LCURVE PERIODG 0.01 0.01 100 4
           AOV/TSA ? ? 0.2 0.0001
           This second command may be used after the first example
           to inspect the frequency interval from 0.2 till 0.21 at higher
           resolution.