A fixed 2013 GJ 674 rotation wave raises velocity prediction error in 2006 and 2019

We test whether a rotation wave fitted to 58 GJ 674 HARPS velocities in 2013 predicts four other dense seasons. Its fixed 36.501-day wave reduces weighted error by 46.8 percent in 2014 and 31.1 percent in 2018. It raises error by 49.6 percent in 2006 and 132.9 percent in 2019. The known planet gives positive gains in all four seasons. Extraction, weight, baseline and Earth-velocity checks retain the rotation gain signs. Small period changes alter long-gap predictions. Fixed-period time-bin resampling has few bins in some seasons. Thus the mixed gains do not measure a spot lifetime or reject a stable orbit. There is no new planet, signal, or independent observation. Code, frozen input, hashes, period profiles, controls and offline steps are included.

astronomy · GJ 674 · HARPS · radial velocity · stellar rotation · prediction · period uncertainty