SBCR (F_λ1, mag_λ1-mag_λ2) for all possible colour indices combination based on λ₁ = V and λ₂ = G_BP, G, G_RP, J, H, and K (from left to right). The mean error associated with F_V and the colour are indicated by a red cross for each SBCR. The three SBCRs on the left (in grey) are shown for indication but should not be used in the context of the BW method (see text). The red arrows show the effect on the SBCRs of a 0.1 magnitude offset in E(B − V).