The secondary eclipse phase in seven V490 Cyg TESS visits decreased by 0.03987 from 2019 to 2024

We measured the secondary eclipse phase in seven public TESS QLP visits of V490 Cyg (TIC 91717090), from 2019 to 2024. Phase is the time from the deeper primary eclipse to the next secondary eclipse, divided by the local fitted period. Separate symmetric profiles, exposure averages, and event backgrounds give a decrease from 0.528526 to 0.488655. The change is -0.0398704 in phase, or -65.465 minutes at a fixed period of 1.14023698 days. The conditional standard error from cycle deletion is 10.6 seconds. The largest shift of the endpoint result across tested analysis choices is 10.7 seconds. These values are not a total error bound. The 238 accepted eclipses place the phase above 0.5 through August 2022 and below 0.5 by February 2024. A test with a different symmetric profile at the real sample times has a maximum bias of 0.19 seconds with no added noise. The data extend observations of known apsidal motion. The 2024 phase is about 11.3 minutes below a forecast from the 2011 central parameters. This residual does not reject the old model because its parameter covariance is not available. The package preserves original data, source code, selection records, numerical results, four figures, and a successful clean offline run. The measurements apply to the stated aperture data and symmetric profile centers. They do not determine a new precise apsidal period.

V490 Cyg · TIC 91717090 · TESS · eclipsing binary · apsidal motion · eclipse timing · QLP · reproducible research