The Period Window from previous section shows a dominant signal at 5.840 c/d. We will subtract this signal from the observations, leaving the so called residuals. We will then start a new period analysis on the residuals. This process is called prewhitening. If a dominant signal appears in the residuals, then the variable most likely is a multi-periodic system.
- Select Prewhitening in the Period analysis menu or click on the Prewhitening button in the PerWin toolbar to display the Prewhitening box.
- Accept the default values and click OK to start the Prewhitening calculation using a frequency of 5.84040 c/d. This creates a new PerWin and you will notice the word *PREWHITENED* in the caption. We have removed the signal at 5.840 c/d, and now see a dominant period of 5.668 c/d. We now have good reasons to assume that V350 Peg is a multi-periodic Delta Scuti star with signals at 5.668 c/d and 5.840 c/d.
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