B0.5IV


MK43 standard:        bet Sco A - B0.5IV 
Underhill47 standard: eps Per - B0.5IV-V [from Morgan, priv. comm.]
		      139 Tau - B0.5IV  [from Morgan, priv. comm.]
Garrison67 standard:  eps Per - B0.5IV
Walborn90 standard:   lam Lep - B0.5IV

# Standards

bet Sco A
  B0.5IV: MK43

eps Per
  B0.5IV-V: Underhill47(stan),Garrison67(stan)

139 Tau
  B0.5IV: Underhill47(stan)

lam Lep
  B0.5IV: Walborn90(stan)

# Other Stars

alf Cru = HR 4731 (alf1 Cru + alf2 Cru; 4" binary)
   B0.5IV+B1V: Hiltner69 
   B0.5IV+B0.5Vn HeI wk: Abt84

   Mermilliod91 reports blended photometry of B-V=-0.258+-0.004, and
   U-B=-0.960. Multiple system dominated by bright A (V=1.25) and B
   (V=1.55). logN_HI = 19.60+-0.10 (York76), 19.85+-0.09 (Bohlin83).
   If we adopt logN_HI = 19.73, adopting the Savage & Mathis (1979)
   logNH/E(B-V) = 4.8e21 atoms/cm^2/mag, E(B-V) = 0.011 mag.  Then
   (B-V)o = (B-V) - E(B-V) = -0.258 - 0.011 = -0.269, and (U-B)o =
   (U-B) - E(U-B) = (U-B) - 0.72*E(B-V) = -0.960 - 0.72*0.011 =
   -0.968.