Mode parameters of δ Scuti stars V830 Her and HD 163032 with four-year data from the Taiwan Automated Telescope Network

We study two δ Scuti stars, V830 Her and HD 163032, using four-year asteroseismic photometric data taken with the Taiwan Automated Telescope Network. We check the consistency of the pulsational frequencies obtained from data of different years and sites with three different methods to remove the artificial frequencies. Fourteen frequencies are detected for V830 Her. Among them, eight are independent modes, one is a harmonic frequency, and five are combination frequencies. Four frequencies are detected for HD 163032. Three are independent frequencies and one is a harmonic frequency. We study the temporal variability of mode frequency, amplitude, and phase. No pattern is found in the temporal variations of the mode parameters for all modes in the period under study. Furthermore, the year-to-year variations of the mode parameters from each site are similar to the differences between two sites. This suggests that the observed variations of mode parameters among different years and different sites are random. We treat the standard deviation of these variations as an estimate of the measurement errors. For the main mode of V830 Her, the estimated error is 0:00004 cd^-1 for frequency, 0.7 mmag for amplitude, and 0.01 cycle for phase.