A7III tet^2 Tau is the best A7III standard, and should probably be considered an anchor standard. tet^2 Tau is the best A7III standard accessible from the south: J0428+1552 MK43 standard: gam Boo - A7III JM53 standards: tet^2 Tau - A7III gam Boo - A7III Morgan71 standard: tet^2 Tau (=HR 1412) - A7IIIA MorganAbt72 standards: tet^2 Tau (=HR 1412) - A7III MK73 dagger standard: tet^2 Tau (=HR 1412) - A7III Cowley76 standard: gam Boo - A7III Houk standard: tet^2 Tau (=HR 1412) - A7III MK78 standard: tet^2 Tau (=HR 1412) - A7III HR 4369 - A7:III:kn Sr II GrayGarrison89 standard: tet^2 Tau (=HR 1412) - A7III(low vsini) GrayCorbally10 standard: tet^2 Tau (=HR 1412) - A7III(low vsini) (J-H)(A7III) = 0.055 ; smoothed relation from giants in Skiff compnedium w/i 15 deg of NGP, 2MASS photometry AAA flags => adopt (J-H)(A7III) = 0.055 [updated 10/30/2020] (H-Ks)(A7III) = 0.040 ; smoothed relation from giants in Skiff compnedium w/i 15 deg of NGP, 2MASS photometry AAA flags => adopt (H-Ks)(A7III) = 0.040 [updated 10/30/2020] (B-V)(A7III) = 0.179 ; HIP 20894 A7III 1989AJ.....98.1049G (B-V)(A7III) = 0.234 ; HIP 12832 A7III 1995ApJS...99..135A (B-V)(A7III) = 0.313 ; HIP 81687 A7III 1999A&AS..137..451G (B-V)(A7III) = 0.320 ; HIP 5737 A7IIIn 1995ApJS...99..135A => adopt (A7III) = 0.27 [updated 10/30/2020] Mv(A7III) = 0.08 ; HIP 20894 A7III 1989AJ.....98.1049G Mv(A7III) = 1.97 ; HIP 5737 A7IIIn 1995ApJS...99..135A Mv(A7III) = 2.37 ; HIP 12832 A7III 1995ApJS...99..135A (note: fainter than Mv(A7V)!) Mv(A7III) = 2.81 ; HIP 81687 A7III 1999A&AS..137..451G (note: fainter than Mv(A7V)!) [EEM 10/30/2020: note Mv(A7V) = 2.23] # No standards GrayGarrison89 and GrayCorbally10 list a low vsini A7III standard, but no high vsini A7IIIn standard. While Garrison94 does not list a A7III anchor star (indeed any anchors with temperature types between A3 and F0), it appears that tet^2 Tau (=HR 1412) should qualify as an A7III anchor. # Primary standard theta^2 Tau = HR 1412 (J0428+1552; V=3.4) *A7III: Adams35,JM53,Jaschek64(most),MorganAbt72,MK73(dagger),MK78,Ortega83,Gray89,GrayGarrison89(low vsini stan.),Gray01,GrayNstars,GrayCorbally10 A7V: Maury1897 F0III: Bertaud67 F0: Cannon Only Hyad classified A7IVn by Morgan65. SB? SMARTS 1.5-m spectra in hand (26Ia blue, 47Ib red). # Weak standard gam Boo = HD 127762 = HR 5435 (J1432+3818; V=3.0) A7III: MK43,Cowley76(standard),Abt81 A7IIIn: Palmer68 A7IV+(n): Gray01 A7IV+: GrayGarrison89 A7III-IV: Abt95 A5V: Adams35,Bouw81 Generally good agreement on "A7" temperature type due to use in MK43. However GrayGarrison89 and Gray01 consider the star to be "IV+" luminosity class. I've decided to list this star as a candidate "A7IV+" standard.