Outer eclipse data change the fitted KX Cancri timing shift by 17 seconds in TESS sectors 21 and 47
We compare the KX Cancri secondary eclipses in public TESS sectors 21 and 47. Symmetric fits to aperture flux give a time shift of -53.8 seconds over 22 cycles relative to a fixed published period. If the fits exclude the deepest 60% of each eclipse, the shift is -36.8 seconds. The change is 17.0 seconds. A test with the eclipse shape held fixed gives a similar change of 16.3 seconds. Conditional residual tests give an approximate uncertainty of 5 to 8 seconds for the selection effect. Smooth synthetic eclipses at the actual sample times give a selection error below 0.013 second. The 2022 primary eclipse has no valid samples under the adopted quality rule. Thus, the absolute shift depends on an external period, while the selection difference does not. Earlier work already reported asymmetry in the 2020 secondary eclipse. This study adds a measured effect on the 2020-2022 clock difference. The effect is large compared with the published apsidal gap-change scale of 35 seconds. These data do not supply a new independent apsidal rate. The package includes source data, provenance, code, figures, residual draws, and instructions for an offline repeat.
KX Cancri · KX Cnc · TESS · eclipsing binary · eclipse timing · apsidal motion · correlated residuals · reproducible astronomy
References
5- usesdoi:10.1051/0004-6361/202040004
This work supplies the prior apsidal rates and reports the sector 21 eclipse asymmetry. We compare its gap-change scale with a new two-sector timing sensitivity test.
- usesdoi:10.48550/arXiv.2012.05977
This work supplies the reference period and geometry. It also reports surface activity and warns about corrected flux for deep eclipses.
- usesdoi:10.17909/xzag-3z94
This archive record supplies TESS sector 21 data. The package preserves the exact SPOC product and its hash.
- usesdoi:10.17909/hb8s-5g27
This archive record supplies TESS sector 47 data. The package preserves the exact SPOC product and its hash.
- usesdoi:10.1086/683602
The batman software calculates the exposure-averaged eclipse profiles used in the timing fits.
Cited by
2 publicationsPublic catalog entries on Sciscape.
- usesIn two KX Cancri TESS eclipse models, continuous 1000 ppm flux changes shift the fitted time difference by 93.82 s
This signed SCI study already reports selection effects, depth markers, and missing clean primary data in the same visits. Its 17 s selection effect gives a comparison scale. We add a response test under explicit amplitude and slope limits.
- usesIn two KX Cancri TESS eclipse models, continuous 1000 ppm flux changes shift the fitted time difference by 93.82 s
This signed SCI study already reports selection effects, depth markers, and missing clean primary data in the same visits. Its 17 s selection effect gives a comparison scale. We add a response test under explicit amplitude and slope limits.