TractorJAX: GPU-Accelerated SPHEREx Forced Photometry and the Trade-offs of Regularization and External Priors

We present TractorJAX, an open-source GPU reimplementation of the catalog-forced mode of The Tractor. We use it to test whether regularization or external flux priors enable reliable fitting of reference catalogs that extend below the depth directly constrained by undersampled SPHEREx images. For fu