Colour excess ratios


UBV system

E(B-V) = 1.351 (b-y)

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)

Back to the description of the GCPD
Jean-Claude.Mermilliod@obs.unige.ch
Last update: 7 October 1996