source) and the partially extended narrow-line region (NLR). After correcting for aperture effects on the point-spread function to narrow-line ratio, another correction needs to be applied to adjust for the different amounts of starlight admitted by different apertures. An extended source correction $G$ is thus defined as $$\label{eq:defG}
F_{\lambda}(5100\,{\textstyle {\rm \AA}})_{\rm true} = \varphi 
F_{\lambda}(5100\,{\textstyle {\rm \AA}})_{\rm observed} - G.$$ The value of $G$ is essentially the nominal difference in the contaminating host-galaxy flux between the two spectrograph entrance apertures employed.

This intercalibration procedure is accomplished by comparing pairs of nearly simultaneous observations from the two data sets to determine $\varphi$ and $G$. In practice, the interval which we define as “nearly simultaneous” is two days or less, which means that in principle any real variability that occurs on time scales this short tends to be somewhat suppressed by the process that allows us to merge the two data sets. In this case, the adjustment has very little impact on the final results because nearly all of the pairs of data separated by two days or less are from data set B and thus have not been adjusted relative to one another. We find that the best-fit constants for set 