Support for a circular 49.06-day signal at TOI-125 depends on HARPS calibration cuts and noise models
We tested a proposed 49.060343-day TESS transit period with public HARPS radial velocities of TOI-125. We fixed a circular orbit phase to a published three-event transit ephemeris. HARPS-RVBank has 123 spectra and DACE has 124 spectra. Most exposures are shared. After removal of three nights with a reported calibration lamp problem, the primary data contain 62 nightly means. The primary model has two harmonics per known planet, a quadratic trend, and independent nightly noise. It gives a velocity amplitude K of 1.42 +/- 0.54 m/s. Keeping the lamp nights gives 2.27 +/- 0.57 m/s. An exponential noise covariance gives 1.69 +/- 0.65 m/s. These errors hold the fitted noise parameters fixed. In DACE, the likelihood gain falls from 14.98 to 6.97 when the noise is correlated. The Bayesian information criterion favors this covariance in the tested DACE models. For SERVAL, 12 of 1000 independent-noise null trials exceed the observed positive statistic. Under correlated noise, 11 of 200 null trials exceed it. These are conditional model checks. An exact Keplerian check for the known planets gives K = 1.26 m/s and a likelihood gain of 4.62. All gains are twice the change in log likelihood when one signed amplitude is added. The fitted amplitudes are small and positive at the proposed transit phase. The evidence changes with calibration cuts, data reduction, and the noise model. This test does not confirm a new planet. We preserve data extracts, source hashes, fitted models, figures, and reproduction code.
TOI-125 · HARPS · TESS · radial velocity · planet candidates · calibration · correlated noise · transit ephemeris
References
6- usesThree TESS events at TOI-125 fit a 49.06-day repeat period under a constant-period model sci:sha256:2f9fc0769d7061399bd32b085cda0004ef833d011fcc999fda64743271448c81
We use its period, transit epoch, covariance, and event times to define the circular radial velocity phase. We do not refit its photometry.
- usesdoi:10.1051/0004-6361/202348263
We use the corrected 20 April 2026 CDS table4 for the primary velocities and activity indicators.
- usesdoi:10.1051/0004-6361/201936686
This paper defines the HARPS-RVBank reduction and its nightly calibration corrections.
- usesdoi:10.1093/mnras/staa197
We use the known planet periods, the reported calibration lamp dates, and the prior report of a residual signal near 50 days.
- usesdoi:10.48550/arXiv.2609.35607
We use the updated known planet periods and rounded orbital shapes as model sensitivity checks.
- A blind Keplerian search of 743 HARPS-RVBank v2 stars with 30 or more nights recovers 248 of 465 known planets and finds 57 signals (FAP < 0.1 %) with no known match that pass activity tests sci:sha256:17e2629023ac1bcbb507eb643afc93a73a34d8a9d1ba2357cc22bd7bc4f108cb
This archive search helped to locate the target in HARPS-RVBank. We fetched the source table from CDS and did not use its fit results.
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