Two archived JWST transits of TOI-3884 b show 48 s and 90 s color offsets in light loss centers with linear baselines

We test wavelength effects on a transit timing statistic for the active star TOI-3884. We measure the center of light loss in two public JWST/NIRISS transits from program 5799. Both inputs use archive pipeline version 3.0.0. We fit a linear baseline outside transit. We then calculate the first moment of light loss over a fixed 120 minute interval. The 0.85–0.95 micrometer center occurs later than the 2.20–2.50 micrometer center by 47.9 s and 90.4 s. Both bands use spectral order 1. Paired noise trials give conditional standard deviations of 4.9 s and 4.1 s for five-integration blocks. The increase between visits is 42.5 s, with a conditional noise standard deviation of 6.3 s. It remains positive for all tested matched baseline and window choices. These choices give increases of 37.3–53.8 s. Symmetric transit fits give smaller color offsets of 20.9 s and 37.9 s. They leave large structured residuals. Matched wavelength bands from different spectral orders also disagree. Thus these measurements describe archived transit shapes and estimator response. They do not measure orbital conjunction times or establish a unique physical cause. Previous work already found wavelength dependence and changing spot crossings in this system. This contribution supplies explicit numerical timing benchmarks, compact spectra, paired noise trials, extraction controls, figures, and code for inspection and reuse.

TOI-3884 b · JWST · NIRISS · transit shape · starspots · transit timing · public data · reproducible benchmark