One-minute season offsets do not remove the HD 191939 timing mass discrepancy in a six-planet model

We test whether season-wide timing errors explain the low fitted mass of HD 191939 c. We reuse 102 published transit times and refit a coplanar six-planet model with Gaussian offsets for each c and d observing season. At a one-minute offset standard deviation, fixing c at eight Earth masses still costs 46.6 chi-square units, compared with 46.5 without offsets. We also examine 75 published injected control transits. Their 12 season means favor zero added scatter and give an upper likelihood reference of 0.85 minutes under independent groups. Thus offsets near the control scale do not explain the mass discrepancy. Across six tested offset scales from zero to 16 minutes, the penalty for fixing c remains 46.5 to 56.9 chi-square units. Large offsets push the free mass toward its imposed lower bound; this is not a precise mass estimate. These results are conditional on the orbital model, selected measurements, covariance and local search. We do not give a new planet mass or a calibrated significance. Code, measured inputs, provenance, fit parameters, figures and reproduction instructions are included.

HD 191939 · transit timing · planet mass · correlated errors · season offsets · injected controls