K3IV Keenan89 does not list a K3IV standard. MK43 standard: del And - K3 III-IV Stromberg30(1930ApJ....71..175S) first noted the existence of subgiants, and commented that while there appear to be K0-K2 subgiants, an analogous K3-K9 subgiant and M subgiant population didn't seem to exist ("Among stars of spectral class K3-K9 subgiants do not seem to occur.". So the apparent edge of the subgiant population around K2/K3 was obvious even around 1930. In recent years, luminosity class "IV" - often used for MK classifications of subgiants, has also been used for some pre-MS stars whose gravities and absolute magnitudes appear to be intermediate between dwarfs and giants - even if they don't correspond to the classic post-MS subgiant population for the stars hotter than ~K3. Gray03 lists 1 K3IV star (HIP 21482 = HD 283750; K3IVke) and 3 K3IV-V stars, and Gray06 lists one K3IV star (HIP 69972 = HD 125072). Unfortunately, both HD 283750 and HD 125072 are consistent with being dwarfs on the HRD. HR 4252 (HD 94386) is the only star classified K3IV in the Bright Star Catalog 5th ed. (Hoffleit91). Classification seems to come from Evans64. There are three "K3IV" in the Hipparcos catalog within 75 pc, but remarkably all have absolute magnitudes consistent with being main sequence stars with Mv ~ 6-7. Among Gray03 and Gray06 stars within 40 pc (only HIP 21482 & 69972): B-V(K3IV) = 1.060 (+- 0.044 sem, +- 0.062 stdev; N=2) V-I(G0IV) = 1.100 (+- 0.080 sem, +- 0.113 stdev; N=2) # Non-standards HD 283750 = HIP 21482 = K3IVke: Gray03 K2.5Ve: Keenan89 K2: Nestorov95 DC white dwarf 124" away. B-V = 1.104, Mv=6.83, star is 0.17 mag above MS, so its a dwarf. HD 125072 = HIP 69972 = K3V: Evans57,Schade53(K3),Houk75,Jaschek64(all) K3IV: Gray06 K0: Cannon K3-K5: Loden76 B-V=1.016, revised HIP => Mv=6.30, only 0.36 mag above MS. Clearly a dwarf. But possibly a good candidate K3V standard?