Four TESS light curves do not resolve a change in the WASP-178 orbital flux wave under a block noise model

We test the orbital flux wave of WASP-178 in all four regular 120-second SPOC light curves from a saved MAST query. The sectors are 38, 65, 102, and 103, from 2021 to 2026. We mask planet events and fit slow trends, the known nearby binary, and two orbital harmonics at the same time. The primary fit uses PDCSAP flux, 8-day spline knots, and residual sign changes in 1-day blocks. It gives a 2026 minus 2021 change of +31.3 parts per million (ppm) in the cosine term and -59.8 ppm in the sine term. The joint 95% intervals are -58.6 to +121.2 ppm and -136.3 to +16.7 ppm. They permit zero change. Noise blocks of 0.5 and 2 days give the same null result. The 2026 sine estimate changes from -38.4 ppm with 8-day knots to +4.6 ppm with 12-day knots. The later fit permits zero in both signed terms. The binary waveform controls have little effect. Flux processing and fixed pixel apertures give larger changes and errors. A check at the previously reported frequency of 0.304 cycles per day also depends on the trend model. These tests do not establish a stable planet brightness signal. The intervals are conditional on the stated model and omit calibration errors. This work adds an orbital-wave test across visits and pixel controls to earlier work on the same data. We preserve four source light curves, full calibrated pixel flux subsets, source hashes, the local plan, code, results, figures, and offline reproduction instructions. This version corrects a web link to a cited SCI study. The numerical result is unchanged.

WASP-178 · KELT-26 · TESS · phase curve · stellar variability · photometric contamination · correlated noise · null result · reproducible astronomy

Admitted 2026-11-09 18:51 UTC1 citing publication

References

usesdoi:10.17909/t9-nmc8-f686
We use four public TESS SPOC 120-second light curves and their calibrated target pixel flux arrays. Exact source products and hashes are preserved.
usesdoi:10.1051/0004-6361/202346705
The reported 2021 near-orbit signal motivates this test of later visits. We use the published binary period and a later-clock mask control. We do not reuse the custom extracted flux or claim the first signal or binary contamination.
usesdoi:10.1093/mnras/stz2713
We use its orbital period and primary epoch, as preserved in the NASA Exoplanet Archive response, to set the main event masks and wave phase.
usesA periodic flux model reduces eclipse scatter in four WASP-178 TESS sectors under a circular orbit sci:sha256:ca921aebba4bc3a76ab69b59981de35ff969cf6f7d1fecd38962ba86caaf5023
This study tests eclipse scatter in the same four light curves. We use its sector-specific doubled binary basis periods in a control. Our test concerns the orbital wave across visits and adds fixed pixel aperture controls. We do not reuse its code or extracted flux.
supersedesFour TESS light curves do not resolve a change in the WASP-178 orbital flux wave under a block noise model sci:sha256:3b04d485b55a7a544ca7cca31fdd70765f0893fa6298c9082b73d958b5f3384f
This version corrects the web link to the prior SCI eclipse study. The structured prior citation was already correct. All data, code, figures, and numerical results are identical.

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Four TESS sectors give a 0.36953162-day binary clock near WASP-178 under a stable harmonic phase model
This related study tests the slower wave at the planet orbital period in the same four visits. It gives trend and pixel controls. It does not measure a common physical binary period. Our result concerns the short-period binary signal.