A6III

# No standards

GrayGarrison89 does not list a A6III standards (the only "A6" standard
of any luminosity class that they list is a II standard: omi Sco).

They list only on A6III variant star: HD 81157 (A6III-IVs; line widths
peculiar).

MK43, JM53 and Houk does not list a A6III standard. 

(J-H)(A6III)   = 0.046 ; smoothed relation from giants in Skiff compnedium w/i 15 deg of NGP, 2MASS photometry AAA flags
=> adopt (J-H)(A6III) = 0.046 [updated 10/30/2020]

(H-Ks)(A6III)  = 0.036 ; smoothed relation from giants in Skiff compnedium w/i 15 deg of NGP, 2MASS photometry AAA flags
=> adopt (J-H)(A6III) = 0.036 [updated 10/30/2020]