KK2V 

Garrison94 lists eps Eri (= HD 22049) as the K2V anchor standard,
but MK73 does not list a K2V dagger standard.

Oddly, all the standards and best examplars appear to be subsolar ([Fe/H] ~ -0.4 to -0.04),
which needs to be accounted for when estimating typical properties for solar composition stars. 

eps Eri and HD 109011 appear to be the best standards.

MK43 standards:       eps Eri (=HD 22049) & S222 (HR 222?) - K2V
JM53 standards:       eps Eri (=HD 22049) - K2V 
                      HD 109011 - K2V
Wilson62 standards:   eps Eri (=HD 22049) - K2V [from JM53]
	              HD 109011 - K2V [from JM53]
Morgan65 standard:    eps Eri (=HD 22049) - K2V
Houk75 standard:      HD 166620 - K2V (see discussion below; listed alf Ser, but probable typo)
KeenanMcNeil76 stan.: eps Eri - K2V
Keenan80 standard:    eps Eri (=HD 22049) - K2V
                      HD 109011 - K2V
Keenan83 standard:    eps Eri (=HD 22049) - K2V
                      HD 109011 - K2V
		      HD 184467 - K2-V 
Turnshek85 standard:  eps Eri (=HD 22049) - K2V
Keenan85 standard:    eps Eri (=HD 22049) - K2V
	 	      HD 109011 - K2V
		      HD 184467 - K2-V
Keenan88 standard:    HD 109011 - K2V
                      HD 184467 - K2V
Keenan89 standards:   eps Eri (=HD 22049) - K2V
                      HD 109011 - K2V
                      HD 184467 - K2V
Strassmeier90 stan:   HD 166620 (=HR 6806) - K2V
Keenan99 standard:    eps Eri (=HD 22049) - K2V
GrayNstars standards: eps Eri (=HD 22049) - K2V
                      HD 166620 (=HR 6806) - K2V
                      HD 184467 - K2V
Pecaut13 standard:    eps Eri (=HD 22049) - K2V

Skiff08 flags three stars as K2V MK standards, all from Keenan89: HD
109011 (K2Ve), HD 184467 (K2V), & HD 22049 (K2V).

(B-V)(K2V) = 0.941 ; sec. stan. NO UMa = HD 109011
<B-V>(K2V) = 0.928 ; 174 HIP d<75pc S/N>8 (+-0.006 sem, +-0.057 stdev)
<B-V>(K2V) =  0.92  ; Fitzgerald70
(B-V)(K2V) =  0.92  ; Johnson66
(B-V)(K2V) = 0.916 ; median SIMBAD K2V d<25pc (N=38)
(B-V)(K2V) =  0.91  ; SchmidtKaler82
<B-V>(K2V) = 0.910 [+-0.012 sem,+-0.051 stdev]; med. for 36 K2V stars ARICNS
(B-V)(K2V) = 0.895 ; Koen10 d<25pc median K2V
<B-V>(K2V) = 0.89  ; Hyades; Wilson62(N=11)
(B-V)(K2V) = 0.890 ; tert. stan. HD 4628
(B-V)(K2V) =  0.89  ; KenyonHartmann95
(B-V)(K2V) = 0.887 ; exemplar HD 68475
(B-V)(K2V) = 0.881 ; prim. stan. eps Eri
<B-V>(K2V) =  0.88  ; Bessell79
<B-V>(K2V) = 0.878 ; 69 Gray 01/03/06 (+-0.006 sem, +-0.033 stdev)
(B-V)(K2V) = 0.876 ; ter. stan. HR 6806/HD 166620
(B-V)(K2V) = 0.87  ; CATSUP d<30pc median (Hinkel17)
(B-V)(K2V) = 0.870 ; exemplar HD 13808
(B-V)(K2V) =  0.87 ; Strassmeier90
(B-V)(K2V) = 0.861 ; exemplar HD 170657
(B-V)(K2V) = 0.854 ; exemplar HD 3222
=> adopt (B-V)(K2V)  = 0.884 *** [updated 8/29/2019] 
=> adopt (U-B)(K2V)  = 0.581 
=> adopt (V-I)(K2V)  = 0.937
=> adopt (V-R)(K2V)  = 0.492
=> adopt (R-I)(K2V)  = 0.445 
=> adopt (V-J)(K2V)  = 1.606
=> adopt (V-H)(K2V)  = 2.034
=> adopt (V-Ks)(K2V) = 2.132
=> adopt (H-Ks)(K2V) = 0.098
=> adopt (J-H)(K2V)  = 0.427
=> adopt (V-Hp)(K2V) = -0.144
=> adopt (W1-W3)(K2V)= -0.037
=> adopt (W1-W4)(K2V)= -0.009
=> adopt (Bp-G)(K2V) = 0.497

(Ks-W1)(K2V) = 0.073 ; EEM trend for d<30pc for B-V=0.884
=> adopt (Ks-W1)(K2V) = 0.073 [updated 12/29/2019]

(G-V)(K2V) =  -0.375 ; HD 115404A PM* K2V
(G-V)(K2V) =  -0.357 ; GJ_144
(G-V)(K2V) =  -0.349 ; GJ_1160
(G-V)(K2V) = -0.323  ; sec. stan. HD 109011
(G-V)(K2V) =  -0.321 ; HD 183870 PM* K2V
(G-V)(K2V) =  -0.304 ; HD 23189 PM* K2V
(G-V)(K2V) =  -0.301 ; HR_222  
(G-V)(K2V) =  -0.285 ; HR_6806
(G-V)(K2V) =  -0.282 ; HD 3765 PM* K2V
(G-V)(K2V) =  -0.280 ; HD 166620 PM* K2V
(G-V)(K2V) =  -0.276 ; HD 23356 PM* K2V
(G-V)(K2V) =  -0.272 ; HD 144628 PM* K2V
(G-V)(K2V) = -0.271  ; smoothed fit f(SpT) G9V-M0V
(G-V)(K2V) =  -0.265 ; HD 220339 PM* K2V
(G-V)(K2V) = -0.263  ; trend d<20pc for V-Ks=2.132
(G-V)(K2V) =  -0.262 ; HD 170657 PM* K2V
(G-V)(K2V) =  -0.261 ; HD 116443 PM* K2V
(G-V)(K2V) =  -0.261 ; HD 23484 PM* K2V
(G-V)(K2V) = -0.254  ; color fit for B-V=0.884
(G-V)(K2V) =  -0.253 ; HD 30876 PM* K2V
(G-V)(K2V) = -0.249  ; pri. stan. eps Eri (corrected)
(G-V)(K2V) =  -0.246 ; * 36 Oph K2V
(G-V)(K2V) =  -0.244 ; HD 67199 PM* K2Vk:
(G-V)(K2V) =  -0.236 ; HD 73667 PM* K2V
(G-V)(K2V) =  -0.181 ; * p Eri A K2V
(G-V)(K2V) =  -0.174 ; * p Eri B K2V
=> adopt (G-V)(K2V) = -0.27 [updated 9/21/2021]

(Bp-Rp)(K2V)=1.0575  ; *_p_Eri_A  K2V
(Bp-Rp)(K2V)=1.079   ; fit for V-Ks=2.132
(Bp-Rp)(K2V)=1.0931  ; *_p_Eri_B  K2V
(Bp-Rp)(K2V)=1.1101  ; HD_4628    K2V
(Bp-Rp)(K2V)=1.1962  ; *_eps_Eri  K2V(k)
=> adopt (Bp-Rp)(K2V) = 1.10 [last updated 3/1/2019]

(G-Rp)(K2V)= 0.581   ; fit for V-Ks=2.132
(G-Rp)(K2V)= 0.5859  ; *_p_Eri_A  K2V
(G-Rp)(K2V)= 0.6051  ; *_p_Eri_B  K2V
(G-Rp)(K2V)= 0.6191  ; HD_4628    K2V
(G-Rp)(K2V)= 0.6707  ; *_eps_Eri  K2V(k)
=> adopt (G-Rp)(K2V) = 0.62 [last updated 3/1/2019]
=> adopt (Bp-G)(K2V) = 0.48 [last updated 3/1/2019; Bp-Rp=1.10, G-Rp=0.62]

<V-Ic>(K2V) = 0.923 (+-0.005 sem, +-0.039 stdev; N=69)
<V-Ic>(K2V) = 0.93 ; Bessell79
<V-Ic>(K2V) = 0.972 (+-0.007 sem, +-0.060 stdev; HIP d<75pc S/N>8 N=174)

<R-Ic>(K2V) = 0.43 ; Bessell79

<V-J>(K2V)   = 1.669 (+-0.009 sem, +-0.108 stdev; HIP d<75pc S/N>8 N=174)
<V-H>(K2V)   = 2.116 (+-0.011 sem, +-0.144 stdev; HIP d<75pc S/N>8 N=174)
<V-Ks>(K2V)  = 2.234 (+-0.011 sem, +-0.150 stdev; HIP d<75pc S/N>8 N=174)
<J-H>(K2V)   = 0.453 (+-0.004 sem, +-0.046 stdev; HIP d<75pc S/N>8 N=174)
<H-K>(K2V)   = 0.114 (+-0.002 sem, +-0.030 stdev; HIP d<75pc S/N>8 N=174)
<Bt-Vt>(K2V) = 1.094 (+-0.008 sem, +-0.093 stdev; HIP d<75pc S/N>8 N=171)
<V-Vt>(K2V)  =-0.097 (+-0.003 sem, +-0.035 stdev; HIP d<75pc S/N>8 N=174) 
<B-K>(K2V)   = 3.163 (+-0.015 sem, +-0.198 stdev; HIP d<75pc S/N>8 N=174)

(U-B)(K2V)   = 0.645 ; HIP d<75pc S/N>8 K2V N=138 (Mermilliod91 photometry)
(U-B)(K2V)   = 0.68  ; Johnson66

(g-r)(K2V) = 0.681 ; Jordi06 pop I (V-R)=>(g-r) for V-R=0.492
(g-r)(K2V) = 0.742 ; Bilir05 (B-V)=>(g-r) for B-V=0.884
(g-r)(K2V) = 0.78  ; Covey07
=> adopt (g-r)(K2V) = 0.74 [updated 10/10/2020]

Teff(K2V) =   4900 K ; Schmidt-Kaler82
Teff(K2V) =   4940 K ; GrayCorbally09
Teff(K2V) =  4950 K ; ter. stan. HD 4628
Teff(K2V) =  4999 K ; exemplar HD 3222
Teff(K2V) =   5000 K ; Bessell79
Teff(K2V) =   5010 K ; GrayCorbally94
Teff(K2V) =  5010 K ; smoothed Teff(SpT) trend
Teff(K2V) =  5012 K ; ter. stan. HD 166620 (see below)
Teff(K2V) =   5013 +- 14 K ; Boyajian12b (N=2)
Teff(K2V) =   5020 K ; EB V2154 Cyg B (BrightTorres17) [Fe/H]=-0.17, 2.2Gyr
Teff(K2V) =  5022 K ; exemplar HD 68475
Teff(K2V) =  5035 K ; mean photometric Teff
Teff(K2V) =  5043 K ; EEM N=269 Teffs
Teff(K2V) =  5060 K ; CATSUP d<30pc median (Hinkel17; N=32)
Teff(K2V) =  5078 K ; exemplar HD 13808 
Teff(K2V) =  5086 K ; pri. stan. eps Eri (see below)
Teff(K2V) = 5100 K ; Teff for d<30pc [Fe/H]=+-0.1 dex dwarfs from Hinkel17 for B-V=0.884
Teff(K2V) = 5107 K ; Teff trend extrapolated to [Fe/H]=0.0 for standards and exemplars
Teff(K2V) =  5108 K ; exemplar HD 170657
Teff(K2V) =  5207 K ; sec. stan. HD 109011/NO UMa (see below, single value)
=> adopt Teff(K2V) = 5100 K (logT = 3.708) [updated 9/4/2020]
[Note: all the standards and exemplars (thus far) are subsolar metallicities ranging
from [Fe/H] ~ -0.4 to -0.04, so the Teff estimates for these are biased to one side

BCv(K2V) = -0.296 mag ; EEM fit to Casagrande06/08/10 (Teff=5080K)
BCv(K2V) =  -0.290 mag ; Schmidt-Kaler82(BCv=-0.42 + 0.13 offset)
BCv(K2V) = -0.276 mag ; Flower96(Teff=5080K)
BCv(K2V) = -0.269 +- 0.018 mag ; pri. stan. Eps Eri (Pecaut13)
BCv(K2V) = -0.267 mag ; Masana06(Teff=5080K)
BCv(K2V) = -0.259 mag ; Bessell98(ATLAS9,logg=4.5,Teff=5080K)
BCv(K2V) = -0.252 mag ; Casagrande18(Teff=5080K,logg=4.5)
BCv(K2V) = -0.222 mag ; Bertone04(ATLAS,Teff=5080K)
BCv(K2V) = -0.221 mag ; pri. stan. HD 22049 = eps Eri (calc using Rains20)
=> adopt BCv(K2V) = -0.26 mag [last updated 8/29/2019 adjusted so that BCv(5772K)=-0.085]

Mv(K2V)  =    6.4  mag ; Schmidt-Kaler82
Mv(K2V)  =   6.39  mag ; exemplar HD 10360 = p Eri B 
Mv(K2V)  =   6.38  mag ; ter. stan. HD 4628
Mv(K2V)  =    6.3  mag ; GrayCorbally09
Mv(K2V)  =   6.25  mag ; median SIMBAD K2V d<25pc (N=38)
Mv(K2V)  =   6.24  mag ; exemplar HD 10361 = p Eri A
Mv(K2V)  =   6.22  mag ; exemplar HD 3222 
Mv(K2V)  =   6.217 mag ; M_Ks=4.085 (d<25pc K2V); V-Ks=2.132
Mv(K2V)  =   6.20  mag ; V-K=2.132 => EEM fit to Reid CNS3 data
Mv(K2V)  =   6.20  mag ; exemplar HD 170657
Mv(K2V)  =   6.18  mag ; pri. stan. eps Eri
Mv(K2V)  =   6.17  mag ; ter. stan. HD 166620
Mv(K2V)  =  6.17  mag ; SIMBAD d<20pc trend for Kdwarfs for V-Ks=2.132 (M_Ks=4.04)
Mv(K2V)  =  6.16  mag ; V-K=2.132 => EEM fit to Jao16
Mv(K2V)  =  6.16  mag ; median Mv K2V d<20pc XHIP
Mv(K2V)  =   6.13  mag ; exemplar HD 68475
Mv(K2V)  =  6.11  mag ; extrapolate for [Fe/H]=0.0 using Mv for standards & exemplars
Mv(K2V)  =  6.09  mag ; B-V=0.884 => Mv(Wright05)
Mv(K2V)  =    6.09 mag ; Wegner07
Mv(K2V)  =   6.08  mag ; sec. stan. HD 109011
Mv(K2V)  = 6.07 mag   ; CATSUP -0.1<[Fe/H]<0.1 d<30pc for B-V=0.884
Mv(K2V)  = 6.07 mag ; Gray01/03/06 dwarfs, xHIP B-V/Mv, Gaspar16 |[Fe/H]|<0.05 "solar": fit for B-V=0.884
Mv(K2V)  =   6.07  mag ; exemplar HD 13808
Mv(K2V)  =  6.05  mag ; Koen10 d<25pc median K2V 
Mv(K2V)  =  6.05  mag ; B-V=0.884 => EEM fit to SIMBAD dwarfs d<25pc 
Mv(K2V)  =    5.9  mag ; Reid04
=> adopt Mv(K2V)   = 6.07  mag [updated 12/15/2020] 
=> adopt M_G(K2V)  = 5.80  mag [updated 12/15/2020] (Mv=6.07, G-V=-0.27)
=> adopt M_Ks(K2V) = 3.938 mag [updated 12/15/2020] (Mv=6.07, V-Ks=2.132)

M_G(K2V) = 5.943 ; SIMBAD d<20pc trend for V-Ks=2.132

M_Ks(K2V) = 4.08 ; median K2V d<25pc (N=24)

logL(K2V) = -0.278+-0.065 ; ecl. binary ASAS_J045304-0700.4A (Helminiak11)
logL(K2V) = -0.310+-0.053 ; ecl. binary EPIC 219511354A in Ruprecht147 [Fe/H]=+0.07+-0.03 (Torres21)
logL(K2V) = -0.428 dex ; Mv=6.07, BCv=-0.26 => Mbol = 5.810
logL(K2V) = -0.49  dex ; pri. stan. HD 22049 = eps Eri (young <1 Gyr star)
=> adopt logL(K2V) = -0.428 dex [updated 9/26/2020]
=> adopt Mbol(K2V) =  5.810 mag [updated 9/26/2020]

Mass(K2V) = 0.912+-0.013 Msun ; ecl. binary EPIC 219511354A in Ruprecht147 [Fe/H]=+0.07+-0.03 (Torres21)
Mass(K2V) = 0.847 Msun ; EEM Mv vs. Mass fit for binaries (Mv=6.17)
Mass(K2V) = 0.834 Msun ; NO UMa (UMa member, dynamical mass, Kiefer18)
Mass(K2V) = 0.8338+-0.0036 Msun ; ecl. binary ASAS_J045304-0700.4A (Helminiak11)
Mass(K2V) = 0.831 Msun ; Eker18 calibration for logL=-0.468
Mass(K2V) = 0.813 Msun ; EEM logL vs. Mass fit for binaries (logL=-0.468)
Mass(K2V) = 0.810 Msun ; Eker15 calibration for logL=-0.468
Mass(K2V) = 0.7542+-0.0059 Msun ; ecl. binary V2154 Cyg B (BrightTorres17) [Fe/H]=-0.17, 2.2Gyr
Mass(K2V) = 0.748 Msun ; Mann18 calib for M_Ks=4.058 
=> adopt Mass(K2V) = 0.82 Msun [updated 10/23/2019]

Rad(K2V) =  0.694 Rsun ; ter. stan. HD 4628 = HR 222
Rad(K2V) =  0.695 +- 0.004 Rsun ; ter. stan. HD 4628 (Yee17)
Rad(K2V) =  0.7152 +- 0.0006 Rsun ; Boyajian12b (N=2)
Rad(K2V) =  0.7232+-0.0091 Rsun ; V2154 Cyg B (BrightTorres17) [Fe/H]=-0.17, 2.2Gyr
Rad(K2V) =  0.738 +- 0.003 Rsun ; pri. stan. eps Eri (Rains20)
Rad(K2V) =  0.749 +- 0.049 Rsun ; ter. stan. HD 4628 (Stassun19)
Rad(K2V) =  0.755 +- 0.038 Rsun ; pri. stan. eps Eri (Stassun19)
Rad(K2V) =  0.760 +- 0.040 Rsun ; exemplar HD 170657 (Yee17)
Rad(K2V) =  0.764 +- 0.056 Rsun ; exemplar HD 170657 (Stassun19)
Rad(K2V) =  0.769 +- 0.052 Rsun ; exemplar HD 3222 (Stassun19) 
Rad(K2V) =  0.771 +- 0.043 Rsun ; sec. stan. HD 109011 (Stassun19)
Rad(K2V) = 0.783 Rsun ; Teff=5100K, logL=-0.428
Rad(K2V) =  0.787 +- 0.041 Rsun ; exemplar HD 13808 (Stassun19)
Rad(K2V) =  0.791 +- 0.045 Rsun ; exemplar HD 68475 (Stassun19)
Rad(K2V) =  0.813 +- 0.044 Rsun ; ter. stan. HD 166620 (Stassun19)
Rad(K2V) =  0.848 +- 0.005 Rsun ; ecl. binary ASAS_J045304-0700.4A (Helminiak11)
Rad(K2V) =  0.920 +- 0.016 Rsun ; EPIC 219511354A in Ruprecht147 [Fe/H]=+0.07+-0.03 (Torres21)
=> adopt Rad(K2V) = 0.783 Rsun [updated 9/26/2020]
(note: most of the standards have slightly smaller radii than the mean likely
due to their subsolar metallicities)

# No standard

Corbally86 does not list a K2V standard. 

# Primary Standards

HD 22049 = eps Eri = GJ 144 = HIP 16537 = 18 Eri = Ran (J0332-0927; V=3.72)
 *K2V: MK43,JM53,Wilson62(stan,JM53),Jaschek64(all),Morgan65,Cowley67,KeenanMcNeil76(stan),Keenan85,Keenan89,Garrison94,Keenan99,Gray03(K2V(k))
  K0: Cannon

  V=3.726+-0.010(Mermilliod91), B-V=0.882+-0.007(Mermilliod91),
  B-V=0.881(HIP), U-B=0.583+-0.013(Mermilliod91).  mbol =
  3.457+-0.016(Pecaut13), hence BCv = mbol - V = 3.457 - 3.726 =
  -0.269.  Teffs: 5097+-19K (Pecaut13), 5077+-35K(Boyajian12).  PASTEL
  (Soubiran10) lists 29 Teffs for eps Eri, median Teff = 5086 K,
  median logg=4.53, median [Fe/H] = -0.09. plx = 312.2191+-0.4673 mas
  (GaiaDR2).  Mv=6.198+-0.011. Gaia DR2 photometry, G and Rp need
  corrected via Evans18: G(corr)= 3.477, Bp(corr)= 4.003, Rp(corr)=
  2.806, (Bp-Rp)(corr)= 1.196, (Bp-G)(corr)= 0.525, (G-Rp)(corr)=
  0.671. G-V=-0.249+-0.011(corr). Rad=0.735+-0.005Rsun(Yee17).
  Rains20 reports values from diameter measurement:
  tetLD=2.144+-0.011mas, Rad=0.738+-0.003 Rsun, fbol=(99.8+-2.5)e-8
  erg/s/cm2 (=>mbol = 3.505+-0.027 IAU2015 scale), Teff=5052+-33K,
  L=0.32+-0.01Lsun (=> logL = -0.49+-0.01). BCv = V - mbol = 3.505 -
  3.726 = -0.221.

# Secondary Standards

HD 109011 = NO UMa = GJ 1160
  K0: Cannon
  K1V: Yoss61
 *K2V: Roman49,JM53,Wilson62(stan,JM53),Abt68,Jaschek78,Levato78,Keenan80,Keenan85,Keenan88,Keenan89(K2Ve)

  Member of ~0.5 Gyr-old Ursa Major cluster. Abt68 uses as their K2V
  standard. B-V=0.941+-0.001(HIP), V=8.08(HIP), V=8.10(Tycho),
  V=8.125+-0.026(Mermilliod91).  PASTEL shows only one published set
  of spectroscopic parameters: Teff=5207+-72K(Gaidos02),
  logg=4.48+-0.12(Gaidos02), [Fe/H]=-0.20+-0.06(Gaidos02).  plx =
  39.4502 +- 0.2049mas(GaiaDR2). GaiaDR2 photometry, none of the bands
  need to be corrected following Evans18: G= 7.777, Bp= 8.317, Rp=
  7.123, (Bp-Rp)= 1.193, (Bp-G)= 0.540, (G-Rp)= 0.653.
  G-V=8.10(+-0.02) - 7.777 =
  -0.323+-0.02. Mv=6.08+-0.01(V=8.10,GaiaDR2). Dynamical mass from
  orbit: 0.834+-0.017 Msun(Kiefer18). 
  
# Tertiary Standards

HD 166620 = HR 6806
 *K2V: 1927MeUpp..28....1L,Adams35,Keenan41,JM53,Wilson62,Cowley67,Hoffleit82(BSC),Houk(stan? see below),Bidelman85(K2),Gray03
  K0: Cannon

  Not officially considered a standard (in JM53, but not as a
  standard), but *all* 8 Skiff compendium references say "K2V". There
  appears to be a typo in Houk75 list of primary standards. Houk75
  lists primary standards of alf Ser as "K2V" followed by HD 166620
  (MK73 dagger) as "K2 III CN 1.5" (from JM53). However these stars
  and their types appear to be switched.  I think Houk75 meant to list
  HD 166620 (K2V) (from JM53) and alf Ser (K2 III CN 1.5) (from MK73
  dagger). So I would argue that this star was indeed probably used as
  a "K2V" standard by Houk75. B-V=0.876+-0.007(HIP),
  V=6.38(HIP). PASTEL median values: <Teff> = 5012K(N=18),
  <[Fe/H]>=-0.19(N=10). Mv=6.17. 

HD 4628 = HR 222 = GJ 33 = BD+04 123 = LHS 121
  K1V: Houk99
 *K2V: MK43(stan),Nassau47,Wilson62,Cowley67,Harlan74,Gray03
  K2.5V: Gray06

  According to Skiff's compilation, "S 222" in MK43 is actually "HR
  222". Jaschek78 agrees.  Wilson62 comment "Balmer & CN weak". Houk
  says "HR 222; UNDETECTED VISUAL DOUBLE p=353°d=2.7arcsec MAG 5.8;
  LHS 121; µ=1.367". V=5.74(HIP), B-V=0.890+-0.008(HIP).  PASTEL
  compendium: <Teff> = 4950K(N=17), logg~4.6, [Fe/H]~-0.3.  Mv=6.38.
  Boyajian13 reports limb-darkened diameter 0.868+-0.004mas,
  plx=134.4990+-0.0890mas(GaiaDR2) => R=0.694Rsun.
  R=0.695+-0.004Rsun(Yee17).
  

# Deprecated standards

HD 45088 = OU Gem = GJ 233A
  K0: Cannon
  K2V HK em: Keenan89,Keenan99(non-stan)
  K2/3Ve: Bopp80
  K3Vk: Gray03

  Similar to HD 3765 - where Keenan's last compilation considered it
  K2V but Gray classified it later (K3V).  In Keenan's later lists,
  but not flagged as one of the standards.  It is a BY Dra variable,
  and the Keenan and Gray types disagree. So probably not the best
  choice of standard.

HD 140573 = HR 5854 = alf Ser
  K2V: HoukStandard
  
  note, this is a V=2.6mag with par=44.5mas. The predicted MS distance
  to a K2V would be 1.2 pc for this magnitude.  Hence, it is not a
  dwarf, let alone a dwarf standard

HD 184467 = GJ 762.1 = Cin 20 1157
  K0V: Bartaya83
  K1V: Roman55,Jaschek64(all),Jaschek78(Roman55),Houk(sec.stand.)
  K2-V: Keenan83,Keenan85
 *K2V: Wilson62,Garcia89,Keenan89,Gray03
  K4V: Keenan88
  K5V: Joy35
  
  Very poor agreement among authors on type.

# Exemplars

HD 13808 = HIP 10301 = UPG 29
  *K2V: Upgren72, Houk75, Gray06

   All Skiff compendium types are K2V. V=8.36(HIP),
   B-V=0.870+-0.000(G,HIP). PASTEL compendium: <Teff> = 5078K(N=4),
   logg=4.38(N=2), [Fe/H]=-0.21(N=2). Mv=6.07. 

HD 3222 = HIP 2743 
   K0V: Przybylski65
  *K2V: Upgren72, Houk75,Gray06
   K3V: Evans65

   V=8.55(HIP), B-V=0.854+-0.006(HIP), V-Ic=0.90+-0.01(HIP). PASTEL
   compendium: <Teff> = 4991K(N=3), logg=4.57+-0.12(Bensby14),
   [Fe/H]=-0.41+-0.07. Mv=6.22. 

HD 68475 = HIP 40051
  *K2V: Upgren72,Houk78,Gray06

   All 3 types in Skiff MK compendium agree.  V=8.78(HIP),
   B-V=0.887+-0.025(HIP), V-Ic=0.93+-0.02(HIP).  PASTEL compendium:
   <Teff> = 5022K(N=2). [Fe/H]=-0.04+-0.05(Gaspar16,N=5). Mv=6.13. 

HD 170657 = HIP 90790
   K0V: Adams35
   K1: 1932LicOB..16...53H
  *K2V: Munch44,Feast57,Bidelman85(K2),Gray06
   K3V: Wallerstein57

   V=6.81(HIP), B-V=0.861+-0.007(HIP).  PASTEL compendium: <Teff> =
   5108K(N=9), logg~4.5-4.6, [Fe/H]=-0.16(N=9). Mv=6.20. 
  
# Other Stars

Morgan65 lists four stars as K2V Hyads: HD 27990, 28878, 28977, & 284414.

RECONS list shows Eps Eri (GJ 144; J0332-0927) as the nearest K2V star.

HD 3765 = GJ 28 = G 132-15 = Cin 20 44
  K2V: Stebbins56,Keenan99(non-stan)
  K2.5V: Gray03
  K5V: Adams35

  Star appeared in Keenan's last (posthumous) MK classification
  compilation
  (https://www.astronomy.ohio-state.edu/MKCool/mkcat.html), who
  considered it K2V (non-standard) but Gray classified it later
  (K2.5V).

HD 148653
   K1V: Bidelman85(K1),Abt81
   K2V: Adam35,Cowley67,Gray03

HD 10360 = HR 486 = p Eri B
   K0V: Evans57
   K1: Houk75
   K1.5V: Corbally84
  *K2V: Gray06
   K3V: Corbally80
   K5V: Stocke91

  "B" component with HR 487. Remarkably poorly constrained spectral
  type.  B-V=0.880(Mermilliod91), V=5.960(Mermilliod91),
  U-B=0.600(Mermilliod91).  PASTEL published values: <Teff> = 5061K
  (N=8), <[Fe/H]> = -0.235(N=6), <logg> = 4.625(N=6).
  plx = 122.1333+-0.0523mas(GaiaDR2). Mv = 6.39. 

HD 10361 = HR 487 = p Eri A 
   K0V: Evans57,Stocke91
   K0/4: Houk75
   K1V: Corbally84
  *K2V: Corbally80,Gray06

  "A" component with HR 486. V=5.810(Mermilliod91),
  B-V=0.850(Mermilliod91), U-B=0.550(Mermilliod91). PASTEL published
  values: <Teff> = 5107K(N=2).  <[Fe/H]> = -0.205(N=2), <logg> =
  4.625(N=2). Somewhat surprising that primary star has fewer quoted
  values than secondary in PASTEL compendium - there may be confusion
  in which ID was assigned to the values?  plx =
  122.0552+-0.0531mas(GaiaDR2).  Mv = 6.24.

HD 192310 = HR 7722
  K0V: Evans57,BSC/Hoffleit91
  K1V?: Bidelman85(NaD strong?)
  K2V: Wilson62(CN strong, spec. bin.),1943HarCi.449....1H,Lindblad22
 *K2+V: Gray06
  K3V: Houk82
  K5V: Adams35

  Awful agreement on published types. 5th brightest K0V in the BSC,
  but most papers have it cooler. Only included since it is a very
  nearby, bright K dwarf.