b-y, m1, c1, Hbeta  ->  E(b-y), Mv 
Crawford, 1979, AJ 84, 1858
Empirical calibrations of the uvby, beta systems III. The A-type stars

delta(m1,beta) = m1(standard,beta) - m1(observed)
delta(c1,beta) = c1(observed) - c1(standard,beta)

m1(standard,beta) via beta from table
c1(standard,beta) via beta from table
Mv(ZAMS,beta)     via beta from table

Reddening:

(b-y)0 = 2.946 - beta - 0.1*delta(c1,beta) - 0.25*delta(m1,beta)  for delta(m1,beta) < 0
(b-y)0 = 2.946 - beta - 0.1*delta(c1,beta)                        for delta(m1,beta) > 0

E(b-y) = (b-y)(observed) - (b-y)0

Calibration:

Valid for:
  2.72 < beta < 2.88

Mv(beta) = Mv(ZAMS,beta) - 9*delta(c1,beta)

standard error for one star: 0.30mag