Lower frequency limit

The frequency where the computation of spectra starts is specified by the keyword lfreq. By default, the lower frequency limit is zero.

Example. The sample project limits illustrates the use of the keyword lfreq. It uses the V photometry of IC4996#89 as input file limits.dat, and the file limits.ini contains the line

lfreq 1

which forces SIGSPEC to perform all computations for frequencies $\ge$ 1 cycle per day. The spectrum limits/s000000.dat is displayed in Fig.7.

Figure 7: Grey: Fourier spectra for the sample project limits. Left: significance spectrum. Right: DFT amplitudes. The significant components are indicated by dots with dashed drop lines (file limits/result.dat). The default sig threshold of 5 is represented by a horizontal dashed line in the left panel. The frequency range is set from 1 to 5 cycles per day using the keywords lfreq and ufreq.