parameter set to 0.5) and no tapering. The final maps have 0.02$\times$ 0.02 arcsec resolution (corresponding to $\sim65$pc on the lensed galaxy plane).

The continuum peak was detected to $>20\sigma$ (see fig. \[fig:alma\_continuum\]). The CO(6-5) image cube was generated with a 70km/s spectral resolution (see fig. \[fig:alma\_CO\]) to increase sensitivity on the line tail. The peak of the spectrum was offset with respect to the expected position, and with an asymmetrical tail towards higher frequencies. The peak estimated over a region that includes the whole galaxy corresponds to a redshift 1.5753$\pm0.0003$, assuming the FWHM of the tail on the higher redshift, that has a Gaussian profile as an estimation of the error, consistent with the past estimates (1.577$\pm0.008$), but evaluated now to a better accuracy. The value of 1.5747$\pm$0.0002 reported by Wong et al. (2017) is well within the line size, but we caveat that both ours and their quoted accuracy values do not take in consideration the asymmetric tail of the line that extends more than $250\ $MHz (half width at half maximum), corresponding to a $\Delta z \sim 0.0024$, improving the accuracy quoted by Bussmann et al. (2013).

While the overall distribution of continuum and CO brightness overlap 