Stable pulsation fits to 2021 TESS data for HD 24355 favor 27.90 days over 27.724 days

We test two reported rotation periods for the magnetic pulsating star HD 24355. We use 44,444 public TESS flux samples from sectors 42, 43, and 44 in 2021. A model with nine pulsation components gives a common frequency spacing of 0.03584219 cycles/day. This gives a period of 27.90008 days. The envelope of tested nominal 95% time-block intervals is 27.845–27.956 days. At a fixed period of 27.724 days, the weighted sum of squared residuals increases by 83.11. At 27.9158 days, it increases by 0.66. These costs are not calibrated significance tests. SAP flux, higher sideband orders, baseline changes, sector subsets, and a model with one gain and one pulsation phase per sector favor periods near 27.9 days. The two strong outer sidebands give 27.893 days when the five strong frequencies are free. A model with free coefficients for each sideband in each sector does not separate the two reported periods. Thus, the result requires a stable relative sideband pattern. It gives a numerical reason to check the 27.724-day entry in Table 3 of arXiv:2312.04199v1. It does not prove a physical rotation change or a table error. The package includes archive files, hashes, code, figures, complete fit results, and offline reproduction instructions.

HD 24355 · TIC 407929868 · TESS · rapidly oscillating Ap stars · stellar rotation · pulsation sidebands · reproducible astronomy · model sensitivity