we need to correct for the differences in the host galaxy contamination. Based on the two-dimensional decomposition of [the]{} [*HST*]{} host galaxy image of Ark 120 by [@Bentz2009], we estimate the relative difference of the host galaxy contribution to 5100 [Å]{} fluxes though the apertures used in our observations and in [@Peterson1998] [to be]{} $\Delta F_{\rm gal}=-(0.9\pm0.3)\times10^{-15}~\rm erg~s^{-1}~cm^{-2}~{\text{\AA}^{-1}}$.

![image](Miller_lc.pdf){width="95.00000%"}

Light Curves of 5100 [Å]{} Continuum and H$\beta$ Fluxes {#sec_data}
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Table \[tab\_lc\] summarizes the photometric and spectroscopic datasets [published]{} to date for Ark 120 in the literature. These datasets [use]{} various apertures and different flux standards of \[\] $\lambda5007$ for absolute spectral calibrations. Intercalibration is needed to correct for these differences.

For spectroscopic data, we select the dataset of [@Peterson1998] as a reference and scale the other datasets [to]{} a common absolute flux of \[\] $\lambda5007$, $F([\text{\ion{O}{3}}])=0.91\times10^{-13}{\rm~erg~s^{-1}~cm^{-2}}$ as the reference dataset used[^2]. To account for the different aperture sizes, we apply a scale factor $\varphi$ and a flux modulation $G$ to the 5100 [Å]{} flux densities and H$\beta$ fluxes of each dataset with respect to the reference [using]{} (e.g., @Peterson1995 [@Li2014]) $$F_{\lambda}(5100\text{\AA}) = \varphi F_{\lambda}(5100\text{\AA})_{\rm obs} + G,$$ and $$F({\rm H\beta}) = \varphi F({\rm H\beta})_{\rm obs}.$$ The values of $\varphi$ 