Tested sine models show over 96 percent reduction of the 7.5-day amplitude in final QLP data for TIC 12189121 in TESS sector 92

We test how public QLP flux products retain a known brightness wave in TIC 12189121, or Gaia DR3 6772575122655104640. We select this source after an audit of nine QLP light curves for four Gaia binary candidates. Sector 92 version 01 supplies 9,307 common valid points over 25.34 days. A quadratic trend and sine terms at P and P/2 give P = 7.5033 days. The fitted fundamental amplitude falls from 52.164 parts per thousand in SYS_RM_FLUX to 0.342 in DET_FLUX. This is a reduction of 99.34 percent. Twenty-four tests of short-cycle periods and trends give reductions above 99 percent. The star was already in the ATLAS MSINE catalog with a master period of 14.917523 days. Four-harmonic fits at that master period describe alternate cycles better. In these fits, the near 7.5-day second harmonic falls by 96.11 to 96.62 percent. Thus, the exact reduction depends on the waveform model. Independent Gaia epoch data have strong period peaks near 7.4636 days, with sparse sampling aliases. Two background-corrected TESS pixel apertures give periods near 7.48 and 7.49 days. The approximate wave centers lie near the target, but close stars remain unresolved. This case shows that final QLP detrending can hide a large known brightness component. We do not establish a planet, a new variable, a physical mode, or an error in the Gaia short-period velocity orbit. The package contains source data, hashes, requests, analysis code, figures, and repeat instructions.

TESS · QLP · Gaia DR3 · stellar variability · detrending · ATLAS · light curves · reproducible astronomy