Nightly corrections supply 38.5 percent of the fitted GJ 176 difference along its 8.776-day vector

We decompose a known difference between HARPS velocity reductions for GJ 176. In 115 selected visits, the printed nightly corrections supply 0.301 m/s along the fitted 8.776-day difference vector. This is 38.5 percent of its 0.781 m/s length in a fixed seasonal rotation model. Deletion of any one night leaves 0.255 to 0.333 m/s. A separate minus-SA term has vector length 0.010 m/s. Gaussian calibration-only ranges include zero for independent pipeline errors but exclude zero for correlation 0.5. The joint calibration covariance is not supplied. These ranges omit other errors and do not assess planet significance. We identify a contribution in the printed corrections, not a calibration fault or a new planet. Code, aggregate results, a figure, input hashes and external retrieval steps are included. The source database is excluded.

astronomy · GJ 176 · HARPS · nightly zero point · calibration covariance · paired velocities