Five TRAPPIST-1 f order-1 spectra have low residual scatter under independent Gaussian errors

We tested five released JWST/NIRISS transit spectra of TRAPPIST-1 f. We used 49 order-1 channels per visit. We fitted unrestricted common channel values and a separate offset and wavelength slope for each visit. We treated the mean released error widths as independent Gaussian standard deviations. The residual statistic is 112.882 for 188 degrees of freedom. The lower-tail probability is 3.05e-6; the two-sided probability is 6.10e-6. A common error scale is 0.775, with a conditional central 95% interval of 0.704 to 0.862. Removing the five suspect red channels of Visit 1 strengthens the low-scatter result. A specified adjacent-channel error correlation of 0.50 gives a two-sided probability of 0.202. We did not measure that correlation. The result tests an independent Gaussian use of the released error summaries. It does not justify reducing the errors or set a physical limit on stellar variability. We provide the source spectra, provenance, code, figures, and offline reproduction instructions.

TRAPPIST-1 f · JWST · NIRISS · transit spectra · error covariance · repeatability · public data