K6III Arguably HR 152 is the best standard following Keenan89 and GrayNstars Keenan89 standards: HR 152 (=HD 3346) - K6IIIa alf Lyn (=HR 3705) - K6III GrayNstars standard: HR 152 (=HD 3346) - K6IIIa (J-H)(K6III) = 0.672 ; smoothed relation from giants in Skiff compendium w/i 15 deg of NGP, 2MASS photometry AAA flags => adopt (J-H)(K6III) = 0.672 [updated 10/30/2020] (H-Ks)(K6III) = 0.180 ; smoothed relation from giants in Skiff compendium w/i 15 deg of NGP, 2MASS photometry AAA flags => adopt (H-Ks)(K6III) = 0.180 [updated 10/30/2020] # No standards MK43, JM53, Landi Dessy & Keenan (1966), Deutsch69, and GrayCorbally10 do not list standards between K5III and M0III # Primary Standard HR 152 = HD 3346 (J0036+4429; V=5.1) K6IIIa: Keenan89(stan),Keenan99,GrayNstars K5III: Adams35,Roman52,Jaschek64(all) K7III: Kirkpatrick91(from KeenanMcNeil76) K5: Cannon,Hossack54 M0III: Henry00 Plx = 5.03+-0.76 mas (ASCC). # Weak standards alf Lyn = HR 3705 = HD 80493 (J0921+3423; V=3.13) K7IIIab: MK73(dagger),Keenan80 K6III: Keenan89(stan),Ginestat94 M0III: Adams26,Bidelman54(Jaschek64,Jaschek78) K5: Cannon K5/M0III: Maury1897 Was a K7IIIab dagger standard in Morgan & Keenan (1973), but then K6III standard in Keenan89.