With quartic backgrounds, 1 to 3 h dip fits stay below 0.5% on a frequency grid within 5% of rotation in seven later TESS sectors of TIC 234284556

We test whether persistent dips at a nearby period escaped earlier fixed-period searches of TIC 234284556. We use seven TESS sectors from 2023, 2025, and 2026. The search tests 401 frequencies within 5% of the published rotation frequency, 400 phases, and symmetric triangles of 1, 2, or 3 hours. Each event has a quartic background. None of the 3,337,245 valid later grid models reaches the declared 0.5% coefficient cut. The sector maxima range from 0.175% to 0.211% of median flux. Both historical dip sectors pass near the known period. Cubic and degree-five backgrounds and the original aperture flux also give no passing later model. We add 4,200 persistent signals with 0.75% depth between grid points. All 4,180 trials with an eligible nearby model are recovered; 20 lack such a model. This is an exploratory test of constant periods and a shared coefficient within each sector. It does not constrain changing depths, accelerating phase, or data gaps. The cut is not a physical depth upper bound or a confidence level. The package preserves raw data, source records, code, full primary grids, every signal trial, numerical checks, and figures.

TIC 234284556 · TESS · stellar rotation · circumstellar material · periodic dips · phase drift · public astronomical data · signal injection