Colour excess ratios

UBV system

uvby system

with UBV

E(b-y) = 0.741 E(B-V)

with Walraven

E(b-y) = 1.653 E(V-B)

Walraven system

with himself

E(B-U) = 0.64 E(V-B)

E(B-L) = 0.43 E(V-B)

E(U-W) = 0.45 E(V-B)

Washington system

With UBV

E(C-M) = 1.066 E(B-V)

E(M-T1) + 0.90 E(B-V)

E(C-T1) = 1.966 E(B-V)

E(T1-T2) = 0.692 E(B-V)

E(M-T2) = 1.592 E(B-V)

E(M-51) = 0.03 E(B-V)

E(T1) = 2.22 E(B-V)

Thuan, Gunn

with himself

E(u-v) = 0.574 E(v-g)

E(v-g) = 0.797 E(g-r)

with UBV

E(v-g) = 0.89 E(B-V)