check our flux calibration, we compared our calibration array with the total MOSFIRE $Y$-band throughput curve.[^1] We also utilized two bright continuum sources which were serendipitously included in our mask, to further verify our absolute flux calibration. Taking a similar approach to that of @kriek15, we first convolved [*HST*]{}/[*Y$_{105}$*]{} images of the two sources and the slit star with a Gaussian kernel with width ${\rm FWHM}_{\rm kernel}^2={\rm FWHM}_{\rm seeing}^2-{\rm FWHM}_{\rm {\it H}_{160}}^2$, to generate the $Y$-band image under the seeing of our spectroscopic observations. Then, we calculated the fraction of light of the two sources that are within our MOSFIRE slit layout. Comparing them to the fraction of light of the star within the slit (on which our absolute flux calibration is based), we calculated the expected flux ratio between our spectroscopic data and the broadband flux (i.e., [*HST*]{}/[*Y$_{105}$*]{}) for the two sources due to the difference in the slit loss. This comparison shows that our absolute calibration (which affects our measurements of line flux and equivalent width, but not the significance of the detection) is accurate within 20%–25%. We thus conservatively add a 30% systematic uncertainty in calibration in our error budget. The systematic uncertainties are indicated in Table 