Three SPARC curves fail a shared nondecreasing law in the stated mass box and error ranges for fixed profiles

Can galaxy rotation curves share one nondecreasing acceleration law when each galaxy has one common distance and inclination scale? We test public SPARC data with fixed mass-profile geometry. We use 137 curves that can each pass alone within three listed velocity errors. Gas and stellar masses vary in a stated box. Distance and inclination vary within three listed errors. No isolated pair of rows from different galaxies fails this test. Joint constraints still give a conflict between UGC06667, UGC00128, and NGC0055. Four rows give a cycle product of 0.9778315251, below the required value of one. This proves that the tested common-law model fails. It gives a lower bound of 0.004868 dex on the maximum extra deviation in acceleration. This is not a measure of intrinsic scatter or statistical significance. A wider mass box, a 5 km/s velocity error floor, or either of two sample cuts removes the graph conflict. A consistent graph does not prove that a common law fits. The study is exploratory and does not test changes to mass-profile geometry. The package contains the data, source hashes, code, figures, fit records, and independent checks. A short proof uses only the Python standard library.

SPARC · radial acceleration relation · galaxy rotation curves · difference constraints · monotone functions · reproducible research