Symmetric fits to 2023 TESS data show a 29-second spread in scaled eclipse spacing for V1094 Tau

We tested whether public TESS data extend the known change in relative eclipse time for the eccentric binary V1094 Tau. Nine complete eclipses in sectors 70 and 71 give three local primary-secondary-primary phase ratios. We scale each ratio to a fixed period of 8.9885474 days. Symmetric fits to SAP flux give a 29.03-second spread in this scaled spacing. The internal timing errors do not explain the spread. Checks use other flux products, local baselines, profile shapes, exposure integration, and a separate edge-midpoint method. The cause remains unknown. These checks share telescope observations and do not exclude errors from eclipse shape or calibration. We also derive a bound for a common eight-year sine delay with a 200-second semi-amplitude. Under these assumptions, the delay can cause a spread of less than 0.01696 second. It cannot explain the measured spread. The new mean agrees with a forecast from 35 historical eclipse events within one combined standard error, but a steady timing model fits the new season poorly. The data do not give a precise new apsidal rate or establish a companion. The package contains all inputs, exclusions, code, timing tables, figures, and offline reproduction commands.

V1094 Tau · TIC 15940209 · eclipsing binaries · TESS · eclipse timing · apsidal motion · public astronomical data · reproducible research