Fourier relative amplitude spectra of V2027 Cyg and the reference star with data taken on May 24, 2010, June 17, 2012, and June 18, 2012. The dashed lines mark the 3-σ level. For the data of June 17 and June 18, 2012, the reference star has lower relative amplitudes (lower middle and lower right panels) because of a larger measured flux. One prominent feature appears at 2.5852 Hz in the upper right panel. It does not have a corresponding feature in the lower right panel, in which a seemingly close peak at about the 3-σ significance level is actually at 2.5954 Hz. The frequency resolution in this analysis is about 1.5 × 10^-4 Hz.