A period average reduces the GJ 887 candidate forecast gain under fixed noise assumptions
We test the reported 2.21661-day signal in public GJ 887 radial velocities. The test holds the published stellar noise parameters and base orbital periods fixed. We use 181 earlier HARPS nights to predict 76 later nights. The fixed candidate period gains 3.38 natural log score units over the four-planet base model. A frequency average over 2.20 to 2.23 days gains 0.97 units with the same signal coefficient prior. The earlier data prefer a different local period peak. In the full 293-night sample, the candidate fit has a chi-square lower by 16.90 than the exact 2.21245-day eccentric harmonic. A sampling calculation shows that the 2019 observations help separate these periods when joined to earlier years. The frequency-average forecast gain ranges from 0.43 to 1.03 in the tested noise and prior checks. The test uses information from the full-data literature and remains conditional. It does not confirm a new planet. The package preserves the source tables, provenance, deterministic code, figures, results, and reproduction instructions.
GJ 887 · radial velocity · planet candidate · eccentric harmonic · predictive density · period uncertainty · Gaussian process · public data · reproducible analysis
References
4- usesdoi:10.1051/0004-6361/202554984
We use the reported GJ 887 candidate period, base orbital periods, and four-planet noise parameter medians. We add a conditional forecast test and a sampling calculation.
- usesdoi:10.26093/cds/vizier/bc-p3/ljd
We analyze and preserve the public HARPS and ESPRESSO velocity tables in CDS catalog J/A+A/707/A93.
- usesdoi:10.1088/0004-637X/709/1/168
This work establishes the ambiguity between an eccentric orbital harmonic and two circular signals near a 2:1 period ratio.
- usesdoi:10.26093/cds/vizier
We obtained the source tables through the VizieR service at CDS.
Cited by
6 publicationsPublic catalog entries on Sciscape.
- 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
Our blind search of GJ 887 finds the known 9.26-day and 21.79-day planets. It does not detect the 50.77-day signal (S = 18.1). Our 39.21-day signal agrees with the published rotation signal.
- Tested consecutive 2027 schedules give fewer local period errors for GJ 887 than season schedules under two fixed noise models
This earlier study tests period-averaged prediction with historical GJ 887 measurements. Our study simulates future measurements and compares schedules.
- usesFixed correlated HARPS noise moves 60-75-day GJ 581 forecast scores toward zero in 54 later velocities
This GJ 887 study informs coefficient integration and period uncertainty in a velocity forecast. We study a different star and test signal continuation. No code is copied.
- Five TESS sectors leave 6.3% of phases unobserved for a circular central GJ 887 d transit model at 50.77 days and 2.29 Earth radii
Related GJ 887 work on period-dependent radial velocity forecasts. No data or code from that study are used here.
- usesTwo noise mixtures give a 0.29 to 1.54 nat gain for the 50.77-day term in 151 older GJ 887 velocities
We use its public-table sampling rule and its treatment of local period uncertainty. Its tested GJ 887 candidate has a different period, 2.21661 days.
- usesAll 65 tested coplanar GJ 887 models at minimum masses with initial circular e and d orbits give less than 0.019 m/s at 2.21661 days after orbit fits
We reuse its source sampling definition, source provenance, and MIT fetch script. This work adds direct gravitational integration.