the model fit and stamp images. The results of our SED fitting analysis show that the high-$z$ solution is preferred over the low-$z$ solution, albeit mildly. For the high-z interpretation, because we did not fit bands shortwards of the Ly$\alpha$ line due to the large uncertainty in modeling the IGM attenuation, and because the source is highly contaminated by a nearby bright source in IRAC channels, only four bands (*Y$_{105}$, J$_{125}$, H$_{160}$*, and $K$) were used to constrain the fit, which can be perfectly matched by SPS models with a certain combination of free parameters and nebular emission strengths, yielding $\chi^2_r \sim 0$.

For the low-$z$ interpretation, the non-detection in the deep optical bands[^3] and the strong break between *z$_{850}$* and *Y$_{105}$* of $\sim$1.8 magnitude yield the only possible solution to be a dusty low-mass ($\log(M_*/M_{\odot})= 9.1 \pm 0.1$) starburst galaxy with specific star formation rate (sSFR) of log(sSFR yr$^{-1}$)$= -7.1 \pm 0.2$. While the reduced chi-square of $\chi^2_r \sim 1.6$ for the low-$z$ solution indicates that it is still regarded a “good” fit, this low-$z$ solution is disfavored by non-detections in deep optical bands: as another measure of goodness-of-fit, we compared the distribution of normalized residuals to the standard 