A5III

HD 73210 is the best A5III standard (southernly accessible too). 

MK43 standards:		 bet Tri - A5III
			 alf Oph - A5III
JM53 standards:          bet Tri - A5III
			 alf Oph - A5III
Cowley69 standards:	 bet Tri - A5III
			 alf Oph - A5III
MK78 standard:           del Cas (=HD 8538) - A5III-IV
GrayGarrison89 standard: HD 73210 - A5III(low vsini) 
GrayNstars standard:     HD 73210 - A5III

(J-H)(A5III)  = 0.065 (+-0.037 sem, +-0.075 stdev) ; N=6 A5III from Skiff compendium w/i 15deg of NGP, 2MASS photometry AAA flags
(J-H)(A5III)  = 0.039 ; smoothed relation from giants in Skiff compnedium w/i 15 deg of NGP, 2MASS photometry AAA flags
=> adopt (J-H)(A5III) = 0.039 [updated 10/30/2020]

(H-Ks)(A5III) = 0.020 (+-0.014 sem, +-0.029 stdev) ; N=6 A5III from Skiff compendium w/i 15deg of NGP, 2MASS photometry AAA flags
(H-Ks)(A5III) = 0.032 ; smoothed relation from giants in Skiff compnedium w/i 15 deg of NGP, 2MASS photometry AAA flags
=> adopt (H-Ks)(A5III) = 0.032 [updated 10/30/2020]

(B-V)(A5III) = 0.140 ; HIP 10064 A5III 1995ApJS...99..135A
=> adopt (B-V)(A5III) = 0.14 [updated 10/30/2020]

Mv(A5III) = 0.05 ; HIP 10064 A5III 1995ApJS...99..135A
[EEM 10/30/2020: note Mv(A5V) = 2.01]

# No standard

GrayGarrison89 list a low vsini standard, but no high vsini standard.

Morgan65 and Houk do not list a A5III standard.

# Standard

HD 73210 = HIP 42327 = Cl* NGC 2632 S 26 (J0837+1916; V=6.7)
  *A5III: GrayGarrison89(low vsini stan.),Abt04,GrayNstars
   A5V: Jaschek64,Reiberot66,Jaschek78(Bidelman56)
   A5: Cannon,Ramberg50
   A6V: Adams35
   A7IV: Wilson50,Abt86
   A3: Ljungren61

   Bright member of Praesepe cluster (Robichon et
   al. 1999). Spectroscopic binary: Abt99 lists K1=20.7 km/s and
   K2=64.5 km/s, period = 12.0 days.  Approximately 1.8 magnitudes
   above MS (Mv = 0.14). SMARTS 1.5-m spectra in hand 
   (26Ia blue, 47Ib red).


# Weak standard

del Cas = HD 8538 = 37 Cas = HR 403 = HIP 6686
  A5V: Cannon(A5),MK53,JM53,Jaschek64,Morgan65,Cowley69(stan),Jaschek78,Kennedy83,
  A5III-IV: Garcia89,Hoffleit91
  A5III/IV: MK78
  A5IV: GrayGarrison89,Gray01 

  Morgan65 lists del Cas as a "fundamental A5 classification standard" w/ bet Ari
  *Everyone* calls this A5-something
  par(HIP)=32.8+-1.5 mas, D~30pc (Local Bubble), B-V=0.160, dMv=-1.6mag (near turnoff)
  Probably should be considered excellent "A5IV" standard
 
bet Tri = HD 13161 (J0209+3459; V=3.0)
  A5IV: GrayGarrison89,Gray01
  A5III: MK43,JM53(SB:), Jaschek64(all)
  A5: Cannon(stan),Olson69

  *All* agree on A5 subtype (indeed it is the HD standard, Cannon
  1918).  B-V = 0.140, HIP2 => Mv=0.05, 1.71 mag above MS. Skiff lists
  Maury & Pickering (1897) listing "A5IV". It is situated right at the
  end of the main sequence on the HR diagram. I adopt Gray's "A5IV" types.