Symmetric fits to five TESS sectors show that QX Car's eclipse gap decreased by 11.4 minutes from 2021 to 2025

We measure 50 eclipse times of QX Car in five public two-minute TESS light curves from 2021, 2023, and 2025. Symmetric spline fits and local event clocks give a normalized primary-to-secondary gap of 1.47956989 days in 2021 and 1.47167636 days in 2025. The later gap is 682.0 seconds shorter. Its standard error from event scatter is 9.9 seconds. A conditional 95 percent interval for the change is -702.5 to -661.5 seconds. An independent ingress-egress midpoint method gives -681.7 seconds. The tested flux and spline choices give changes from -682.1 to -679.0 seconds. Absolute visit gaps can shift by tens of seconds under these choices. A fixed-ellipse conjunction model shows strong eccentricity dependence. The published apsidal rate of 0.01222 degrees per cycle fits the three gaps at eccentricity 0.27399, about 1.34 published standard errors below 0.278. Thus the measured trend does not require a new physical anomaly. The contribution is a timing data set through 2025 and a test of the orbit assumptions. The scatter errors do not include all eclipse-shape or processing errors. The package preserves source FITS files, provenance, code, timing tables, controls, figures, and repeat instructions.

QX Car · TESS · eclipsing binary · eclipse timing · apsidal motion · eccentricity · public data