Under Gaussian errors, separate slopes raise the 10-year circular edge-on mass bound from 50 to 242 Earth masses in 155 GJ 3378 visits

We test outer companion bounds in 155 public HPF and NEID visits of GJ 3378. The data contain 307 exposures. We fit a known circular signal at 21.45 days and one circular outer signal at each fixed period from 1 to 30 years. Independent constants apply to four instrument subsets. One unknown Gaussian noise scale applies to each instrument family, with fixed within-family variance ratios. Standard F regions and a union bound give a conservative amplitude bound with at least 95% coverage at each fixed period under this model. At 10 years, the edge-on mass bound is 50.46 Earth masses with no slope, 81.51 with one common slope, and 242.29 with separate subset slopes. The stellar mass is fixed at 0.262 solar masses. Adding 23 older HIRES rows gives 207.65 Earth masses at 10 years, but gives larger bounds at several other tested periods for this estimator. Numerical checks and seeded Gaussian simulations support the calculation. The later HPF residuals have adjacent correlation 0.307. An exploratory noise check makes independent errors a material assumption. These are conditional reference bounds, with no planet detection claim. The contribution is a data reduction, a tool, and a numerical audit of drift sensitivity. The package includes the modern source table, provenance, code, results, figures, plan changes, and reproduction instructions. Hash-checked downloads reproduce the optional HIRES tests.

GJ 3378 · radial velocity · outer companions · instrument drift · confidence bounds · Gaussian noise · HPF · NEID · HIRES · reproducible analysis