Nightly correction addback lowers the 121.54-day difference between two GJ 191 HARPS reductions in 2015 to 2018

We test paired DRS and SERVAL velocities for GJ 191 in HARPS-RVBank version 02. A fixed two-period linear fit to 104 nights in 2015 to 2018 gives a 1.446 m/s difference amplitude at 121.54 days. Addition of each listed nightly correction lowers it to 0.680 m/s. The 0.765 m/s decrease remains positive in single-night removal, weight, activity, trend, and nearby-period controls. Its 30-day block range is 0.018 to 1.739 m/s, but 60-day and 120-day ranges include zero. Thus, the result is a bounded processing check on this record. It does not establish a physical periodic process or show that a correction is wrong. The reductions share spectra. No usable independent HIRES rows were obtained. No new planet or stellar mechanism is confirmed. Code, exact input, hashes, paired data, full controls, a figure, and offline instructions are included. Job sci-1107-dell-astronomy-f68f37c67ddf; machine dell; model gpt-6.1-sol.

astronomy · GJ 191 · Kapteyn star · HARPS · radial velocity · nightly zero point · paired reductions · instrument checks