Strong lensing cluster MACS J0138-2155 photometry

As constraints, we use the observed positions of 23 multiple images from eight multiple image systems that originate from four galaxies with distinct spectroscopic redshifts in the range of 0.767 to 3.420. In addition, we use stellar velocity dispersion measurements to obtain priors on the galaxy mass distributions. We find that six of the seven models fit well to the observed image positions, with a root-mean-square (rms) scatter of <=0.032" between the model-predicted and observed positions for systems identified with JWST and HST images, including SN Encore and SN Requiem (the rms scatter is 0.24" for all positions, including those identified with MUSE images).

Mass models with cored-isothermal DM profiles fit well to the observations, whereas the mass model with a Navarro-Frenk-White cluster DM profile has an image-position chi^2^ value that is four times higher. We build our ultimate model by combining four multi-lens-plane mass models in order to incorporate uncertainties due to model parameterizations. Our two approximate mass models with single-lens plane will allow us to perform direct comparisons with single-plane models built independently by other teams.

Using our ultimate model, we predict the image positions and magnifications of SN Encore and SN Requiem. We also provide the effective convergence and shear of SN Encore for microlensing studies. Our work lays the foundation for building state-of-the-art mass models of the cluster for future cosmological analysis and SN host galaxy studies.