The True Minimum Distance of Some Narrow-Sense BCH-Codes of Length 255

Using equivalent codes it is shown that the BCH-bound of the following narrow-sense BCH-codes already yields the true minimum distance: 255,87,53, 255,107,45, 255,115,43, 255,123,39, 255,131,37, 255,147,29, 255,163,25, 255,179,21. For the remaining two narrow-sense BCH-codes of length 255 in the book of F.J. MacWilliams and N.J.A. Sloane The theory of error-correcting codes (1977) page 261, figure 9.1, whose true minimum distance is still unknown, upper bounds for the minimum distance are given which differ by at most two from the corresponding BCH-bounds