The transit timing and transmission spectrum of hot Jupiter WASP-43 b from a decade of multiband transit follow-up observations

We present a new set of 35 transit light curves of the hot Jupiter WASP-43 b, obtained through the SPEARNET network. These datasets were analyzed together with previously published ground-based observations, as well as space-based data from TESS, Hubble Space Telescope (HST), and JWST, to refine the planetary parameters of WASP-43 b. A total of 188 midtransit times, measured with TransitFit, were analyzed for potential timing variations. The transit timing variations do not show any significant evidence of orbital decay. Atmospheric retrievals using HST/WFC3 G141 transmission spectra suggest that higher-temperature solutions are associated with higher water abundances. However, when these data are combined with observations from ground-based telescopes, TESS, and JWST, the increased modeling complexity across the broad wavelength baseline presents significant challenges for atmospheric characterization. These results highlight that high-precision, multi-instrument datasets will be necessary to break existing degeneracies in the atmospheric modeling of this target in the future.