Lessons Learned Using JWST Transit Spectroscopy to Test Stellar Limb Darkening Models

We use legacy-quality JWST observations including data from the JWST Telescope Scientist GTO program to illustrate the challenge of distinguishing between data analysis issues, errors in models of stellar limb darkening, and actual exoplanet atmosphere signals. Potential issues include: fitting a light curve not that does not sample disk center, fitting unbinned noisy data, using an approximate limb-darkening laws, biased parameterization (e.g., q1 and q2), strong parameter covariance (e.g., u1 and u2), using 1D atmosphere models, and the impact of stellar magnetic fields. Once issues like these are resolved, JWST transit light curves will provide strong constraints on stellar limb-darkening in spectroscopic bins from 0.6 to 12 µm.