be $z=1.94$. Its photometric redshift, $z_{\rm phot}=1.87^{+0.07}_{-0.08}$ [@dahlen13], is in excellent agreement with the inferred [\[O[ii]{}\]]{} redshift, thus we conclude that the detected line is the [\[O[ii]{}\]]{} doublet. This [\[O[ii]{}\]]{} doublet strengthens the possibility that the detected emission in z7\_GSD\_3811 is Ly$\alpha$ and not an *unresolved* [\[O[ii]{}\]]{} doublet. The left panel of Figure \[fig:serendi\] shows that the doublet in this object is spectrally well-resolved both in the 1D and 2D spectra, yet the observed wavelength and S/N are similar to those of z7\_GSD\_3811.

The second object (R.A. = 3:32:50.48, decl. = $-$27:46:56.0 (J2000)) shows a prominent emission at $\lambda_{\rm obs}=$ 10398 Å, which we identified as an [\[O[iii]{}\]]{}$\lambda$5007 line (right panel of Figure \[fig:serendi\]). The other line of the doublet ([\[O[iii]{}\]]{}$\lambda$4959) is behind a sky line but still visible, and H$\beta$ is detected at 5.6$\sigma$. Upon close inspection, we noted that the emission has an offset of 4–5 pixels along the spatial axis from our original target, which corresponds to 07–09. We identified a galaxy in proximity of our original target at this distance, thus we concluded that the emission is not from our target but from a foreground galaxy at $z=1.08$.

Stellar Population Modeling and Stacking Analysis {#sec:sedfit}
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