F9III

The only quoted F9III standard (psi^3 Psc by Keenan) is considered
G0IIIa by most other authors.

Keenan89 standard: psi^3 Psc (=HD 6903) - F9IIIa

(J-H)(F9III) = 0.296 ; smoothed relation from giants in Skiff compendium w/i 15 deg of NGP, 2MASS photometry AAA flags
=> adopt (J-H)(F9III) = 0.296 [updated 10/30/2020]

(H-Ks)(F9III) = 0.081 ; smoothed relation from giants in Skiff compendium w/i 15 deg of NGP, 2MASS photometry AAA flags
=> adopt (H-Ks)(F9III) = 0.081 [updated 10/30/2020]

# No standard

MK43, JM53, MorganAbt72, Houk, MK78, GrayNstars, and GrayCorbally10 do
not list a F9III standard.

None of the stars in Skiff's (2010) compiled catalog of spectral types
lists a star with "F9III" type from multiple references. None of
Gray's papers lists any "F9III" stars.

# Weak standard 

psi^3 Psc = 81 Psc = HR 339
  G0III: Harlan69,MorganAbt72(stan),MK73(dagger),Gray89,GrayNstars,GrayCorbally10
  G0IIIa: Gray01
  F9IIIa: Keenan89(stan)
  F5III: Adams35

  Considered "G0III" by nearly everyone, but F9III by Keenan89. Part
  of the nebulous F9/G0 boundary between Morgan and Keenan's
  works. I'd stick with Morgan/Gray/Corbally on "G0IIIa"
  vs. Keenan's "F9IIIa". Arguably, 31 Com has a stronger pedigree at
  "G0III" than 81 Psc. 

# Non-Standards

HD 74868 (J0844-4432; V=6.6)
   F9III-IV: Keenan89(non-standard)