Steven Kawaler edited sectionLight_Curve_A.tex  about 10 years ago

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Here, however, we will adopt for our discussion the more precise parameters derived from spectroscopy: \teff\ $= 11{,}270\pm170$ K and \logg\ $= 8.18\pm0.05$ \citep{2011ApJ...743..138G}. The spectroscopy of GD\,1212 is notable in that much of it was collected in order to identify the then-dominant mode at 1160.7\,s, by measuring the pulsation amplitude as a function of wavelength with time-resolved spectroscopy from the Bok 2.3 m Telescope at Kitt Peak National Observatory. However, the identification was inconclusive given the variable, low amplitude of the pulsations \citep{Desgranges08}.  A Fourier transform (FT) of our entire dataset is shown in Figure~\ref{fig:GD1212ft}, which orients us to the dominant frequencies of variability. An FT of our entire dataset finds significant variability ranging from 19.2 \muhz\ $\muhz$\  (14.5\,hr) down to 2703.9 \muhz\ $\muhz$\  (369.8\,s), which is shown in full in the top panel of Figure~\ref{fig:GD1212ft}. The only periodicity detected with marginal significance at longer frequencies occurs at 4531.8 \muhz\ (0.012\% amplitude), which is an instrumental artifact sampling the long-cadence exposures of 29.4\,min that often appears in short-cadence {\em Kepler} data, so we do not include it in our analysis. The highest-amplitude variability in GD\,1212 occurs in the region between $810-1210$\,\muhz\ ($826-1234$\,s). This region bears the evidencing at least 19 independent pulsation modes, which we show in more detail in the bottom panels of Figure~\ref{fig:GD1212ft}. However, the amplitudes of variability in this region are not stable over our 26.7 days of observations, so we additionally display the FT of just our final 9.0-day light curve. We also find a number of nonlinear combination frequencies of these highest-amplitude pulsations, which we discuss further in Section~\ref{sec:nonlinear}.