Note that [180] claimed to measure a slope of 3 for the BTFR, but they relied on unresolved line-widths from single dish
21 cm observations to estimate rotation velocity rather than measuring
from resolved rotation curves. Line-widths give a
systematically different estimate of the slope of the BTFR than
, even for the same galaxies [277, 340, 475], and they
cannot be related at all to the circular velocity of the potential at the virial radius, nor to the prediction of MOND (Section 5
and 6).