Lens modeling results for the 1.2 mm dust continuum emission and spectral lines in HerBS-89a (identified in the right most panels). In each row, from left to right: observed image (with the synthesized beam shown in the lower left corner) and critical curve (red line); reconstructed model image convolved with the PSF; residuals; reconstructed model image at full angular resolution; and (separated and with a different angular scale) reconstructed source-plane image and caustic. The residuals are within ±2.5σ, showing that the model agrees well with the data. The cross shows the coordinates of the phase center of NOEMA observations (RA 13:16:11.52 and Dec +28:12:17.7 in J2000). The OH⁺ absorption lines have been inverted to allow for a positive normalization of the Sérsic profile reconstruction.