UDCT v5.5: Frozen Static Ψ_BD on Official SPARC Q=1 — Baryonic Tully–Fisher Relation Compared with MOND

Locked result: official SPARC Q=1 BTFR, N=83, residual scatter σ=0.248 dex (identical for frozen UDCT and MOND). No last-radius rotmod proxy. This technical note uses SPARC Table 1 (inclination i>30 deg; Vf>0) and the frozen static UDCT scale ξ0 = 1.082×10^−10 m s^−2. Baryonic mass follows Mb = 0.5 L[3.6] + 1.33 MHI. Residual scatter about Vf^4 = G Mb ξ0 and Vf^4 = G Mb a0 is 0.248 dex. The stellar-distance subset (N=36) tightens to 0.182 dex; Hubble-flow distances (N=47) remain at 0.290 dex. The two laws differ only by log10(a0/ξ0)=0.045 dex. LITTLE THINGS RAR is not locked, because the public Oh+2015 table provides Vobs only. Companion code: https://github.com/wspaik5/UDCT_v5.5_SPARC_Q1_BTFR_ReproducibilityRelated: UDCT v5.4 RAR lock, https://doi.org/10.5281/zenodo.22709585