M1.5V

Kirkpatrick(in GrayCorbally09) call Gl 205 the M1.5V primary standard. This
is agreement among many sources (Keenan, Kirkpatrick, Hawley, Reid, Houk) as
a M1.5V.

Both the primary and secondary standards appear to be metal-rich, with
radii larger and absolute magnitudes tenths of a magnitude brighter
than average for the type.

KeenanMcNeil76 standard:        GJ 49 - M1.5V
Keenan80 standard:              GJ 205 (=HD 36395) - M1.5V
Keenan83 standard:              GJ 205 (=HD 36395) - M1.5V
	                        GJ 570B (=HD 131976) - M1.5V
Turnshek85 standard:            GJ 205 (=HD 36395) - dM1.5
Keenan85 standard:              GJ 205 (=HD 36395) - M1.5V
Corbally86 standard:            GJ 205 (=HD 36395) - M1.5V 
Keenan88 standard:              GJ 205 (= HD36395) - M1.5V
                                GJ 570B - M1.5V
Keenan89 standard:              GJ 205 (= HD 36395) - M1.5V
                                GJ 570B (=HD 131976) - M1.5V
Kirkpatrick91 standard:         GJ 205 (=HD 36395) - M1.5V
Henry02 standards:              GJ 15A - M1.5V (from Henry94)
				GJ 205 - M1.5V (from Kirkpatrick91)
				GJ 526 - M1.5V (from Henry94)
				GJ 625 - M1.5V (from Henry94)
				GJ 880 - M1.5V (from Henry94)
GrayAtlas standard:             BD+43_44A - M1.5V
GrayNstars standard:            GJ 570B (=HD 131976) - M1.5V
Kirkpatrick(in GrayCorbally09): GJ 205 - M1.5V
	       			GJ 570B - M1.5V

Joy74 M1.5V stars appear to be approximately M1-V (~M0.75+-1 subtype)
on the Kirkpatrick91 system.

(B-V)(M1.5V)  =  1.415 ; exemplar GJ 366 = Ross 434 
(B-V)(M1.5V)  =   1.448; deprecated stan. GJ 526
(B-V)(M1.5V)  =  1.464 ; exemplar GJ 908 = LHS 550 
(B-V)(M1.5V)  = 1.474  ; pri. stan. GJ 205 (Landolt83)
(B-V)(M1V)    = 1.48   ; adopted
(B-V)(M2V)    = 1.50   ; adopted
(B-V)(M1.5V)  = 1.512  ; sec. stan. GJ 880 (Mermilliod91)
(B-V)(M1.5V)  =   1.567; deprecated stan. GJ 15A
=> adopt (B-V)(M1.5V) = 1.49 [updated 7/5/2020]

(V-I)(M1.5V)  = 2.15  ; Hawley96
(V-I)(M1.5V)  = 2.076 ; pri. stan. GJ 205 (Landolt83)

<V-J>(M1.5V)  = 3.36 (+-0.23 stdev) ; Lepine12

(V-Ks)(M1.5V) = 4.156 ; pri. stan. GJ 205 (estimated from V-R color)
(V-K)(M1.5V)  =  4.15  ; Hawley96
(V-Ks)(M1.5V) = 4.149 ; sec. stan. GJ 880
(V-Ks)(M1.5V) = 4.116 ; exemplar GJ 134 = HD 275122 
(V-Ks)(M1.5V) = 4.104 ; pri. stan. GJ 205 (from synthetic Ks mag from Mann15)
(V-Ks)(M1.5V) = 4.102 ; pri. stan. GJ 205 (estimated from V-I color)
(V-Ks)(M1.5V) = 4.045 ; ter. stan. GJ 526
(V-Ks)(M1.5V) = 4.014 ; pri. stan. GJ 205 (estimated from B-V color)
(V-Ks)(M1.5V) = 3.986 ; exemplar GJ 366 = Ross 434 
(V-Ks)(M1.5V) = 3.940 ; exemplar GJ 908 = LHS 550 
=> adopt (V-Ks)(M1.5V) = 4.10   [last updated 11/1/2019]
=> adopt (U-B)(M1.5V)  = 1.171
=> adopt (B-V)(M1.5V)  = 1.484 
=> adopt (V-I)(M1.5V)  = 2.075
=> adopt (V-R)(M1.5V)  = 0.974
=> adopt (R-I)(M1.5V)  = 1.101
=> adopt (V-J)(M1.5V)  = 3.265
=> adopt (V-H)(M1.5V)  = 3.873
=> adopt (H-Ks)(M1.5V) = 0.227
=> adopt (J-H)(M1.5V)  = 0.608
=> adopt (I-Ks)(M1.5V) = 2.031**fix 
=> adopt (K-W1)(M1.5V) = 0.140

(G-J)(M1.5V)   = 2.312 ; Bentley18/interp
(G-Ks)(M1.5V)  = 3.162 ; Bentley18/interp
(Ks-W2)(M1.5V) = 0.226 ; Bentley18/interp
(W1-W2)(M1.5V) = 0.080 ; Bentley18/interp

(Ks-W1)(M1.5V) = 0.147 ; Bentley18/interp
(Ks-W1)(M1.5V) = 0.140 ; fit to Winters15 data for V-Ks=4.10
(Ks-W1)(M1.5V) = 0.110 ; Best18 
(Ks-W1)(M1.5V) = 0.099 ; Avenhaus12 for V-Ks=4.10
=> adopt (Ks-W1)(M1.5V) = 0.135 [updated 12/29/2019]

(Bp-Rp)(M1.5V) = 2.1050 ; GJ_908      exemplar
(Bp-Rp)(M1.5V) = 2.1161 ; GJ_366      exemplar 
(Bp-Rp)(M1.5V) = 2.1174 ; BD+18_3421  
(Bp-Rp)(M1.5V) = 2.1130 ; GJ_526      ter. stan.
(Bp-Rp)(M1.5V) = 2.1254 ; GJ_134      exemplar 
(Bp-Rp)(M1.5V) = 2.1257 ; GJ_205      pri. stna.
(Bp-Rp)(M1.5V) = 2.1553 ; GJ_880      sec. stan.
(Bp-Rp)(M1.5V) = 2.1649 ; MCC_135     
(Bp-Rp)(M1.5V) = 2.1731 ; V*_GX_And   
(Bp-Rp)(M1.5V) = 2.1805 ; BD+61_195   
(Bp-Rp)(M1.5V) = 2.2773 ; CD-48_11837
(Bp-Rp)(M1.5V)=  2.3002 ; G_202-48_   
(Bp-Rp)(M1.5V) = 2.3033 ; HD_156384C  
=> adopt (Bp-Rp)(M1.5V) = 2.13 [updated 7/10/2020]

(G-Rp)(M1.5V) = 1.0108 ; GJ_366       exemplar 
(G-Rp)(M1.5V) = 1.0148 ; GJ_134       exemplar 
(G-Rp)(M1.5V) = 1.0165 ; BD+18_3421   M1.5V
(G-Rp)(M1.5V) = 1.0170 ; GJ_809       exemplar 
(G-Rp)(M1.5V) = 1.0174 ; GJ_205       pri. stan.
(G-Rp)(M1.5V) = 1.0205 ; GJ_526       ter. stan.
(G-Rp)(M1.5V) = 1.0278 ; MCC_135      M1.5V
(G-Rp)(M1.5V) = 1.0291 ; GJ_880       sec. stan. 
(G-Rp)(M1.5V) = 1.0309 ; BD+61_195    M1.5V
(G-Rp)(M1.5V) = 1.0340 ; V*_GX_And    M1.5V
(G-Rp)(M1.5V) = 1.0643 ; CD-48_11837  M1.5V
(G-Rp)(M1.5V)=  1.0679 ; G_202-48_    M1.5V
(G-Rp)(M1.5V) = 1.0690 ; HD_156384C   M1.5V
=> adopt (G-Rp)(M1.5V) = 1.02 [updated 7/10/2020]
=> adopt (Bp-G)(M1.5V) = 1.11 [updated 7/10/2020; Bp-Rp=2.13,  G-Rp=1.02]

(Bp-G)(M1.5V) = 1.0925 ; GJ_526
(Bp-G)(M1.5V) = 1.1084 ; GJ_205 
(Bp-G)(M1.5V) = 1.1262 ; GJ_880

M_G(M1.5V) =   8.31848 ; HD 131976                    
M_G(M1.5V) =   8.31952 ; HD 36395                     
M_G(M1.5V) =   8.53075 ; BD+57 2735                  
M_G(M1.5V) =   8.60896 ; HD 216899                    
M_G(M1.5V) =   8.69469 ; BD+61 195                    
M_G(M1.5V) =  8.83694 ; HD 318327                   
M_G(M1.5V) =  8.89001 ; * tet Per B
M_G(M1.5V) =  8.993   ; SIMBAD d<20pc trend for V-Ks=4.10
M_G(M1.5V) =  9.004   ; trend d<10pc SIMBAD
M_G(M1.5V) =  9.02662 ; CD-36 2458                  
M_G(M1.5V) =  9.0712  ; HD 154363B                    
M_G(M1.5V) =  9.13619 ; MCC 135                      
M_G(M1.5V) =  9.18074 ; BD+18 3421                   
M_G(M1.5V) =  9.19005 ; CD-53 570                   
M_G(M1.5V) =  9.28757 ; G 125-30                    
M_G(M1.5V) =   10.0797  ; HD 156384C                   
M_G(M1.5V) =   10.0812  ; G 202-48
=> adopt M_G(M1.5V) = 9.1 [updated 7/5/2020]

(G-V)(M1.5V) = -0.872  ; polynomial fit to SIMBAD d<25pc M dwarfs
(G-V)(M1.5V) = -0.8695 ; GJ_205 
(G-V)(M1.5V) = -0.8532 ; GJ_526  
(G-V)(M1.5V) = -0.8449 ; GJ_880
=> adopt (G-V)(M1.5V)  = -0.85 [updated 12/10/2018]
=> adopt (G-Ks)(M1.5V) = 4.12 + -0.85 = 3.27 [updated 11/1/2019]
=> adopt M_G(M1.5V)    = 9.05 = Mv + (G-V) = 9.90 + -0.85 [updated 4/9/2020]


Teff(M1.5V) =  3533 K ; Morrell19 <Teff> for stars w/i +-0.05 mag of M_Ks=5.82
Teff(M1.5V) =   3535 +- 14 K ; Pecaut13 (deprecated stan. GJ 15A)
Teff(M1.5V) =  3564 +- 44 K ; Lepine12
Teff(M1.5V) =   3563 +- 11 K ; deprecated standard GJ 15A (Boyajian12)
Teff(M1.5V) =   3596 +- 25 K ; Pecaut13 (GJ 880)
Teff(M1.5V) =  3600 K ; Rajpurohit13 (N=2; LHS 14A, LHS 65A)
Teff(M1.5V) = 3610 K ; Rad=0.4743Rsun for Mann15 calib for M_Ks=5.8, [Fe/H]=0.0
Teff(M1.5V) =  3640 K ; empirical L-R relation, logL=-1.464
Teff(M1.5V) =  3650 K ; ter. stan. GJ 526
Teff(M1.5V) =  3674 +- 10 K ; Boyajian12b (N=4)
Teff(M1.5V) =  3683 K ; smooth Teff(SpT) trend
Teff(M1.5V) =   3703 +- 36 K ; Pecaut13 (GJ 205)
Teff(M1.5V) =  3750 K ; sec. stan. GJ 880 (median Teff, but metal-rich)
Teff(M1.5V) =  3760 K ; pri. stan. GJ 205 (median Teff, but metal-rich)
=> adopt Teff (M1.5V) = 3610 K (logT = 3.561) [updated 4/9/2020]

BCv(M1.5V) = -1.529 +- 0.022 ; deprecated standard GJ 15A (Pecaut13)
BCv(M1.5V) = -1.523 +- 0.019 ; pri. stan. GJ 205 (Pecaut13)
BCv(M1.5V) = -1.50           ; BC_Ks=2.60, V-Ks=4.10
BCv(M1.5V) = -1.494 +- 0.024 ; sec. stan. GJ 880 (Pecaut13)
BCv(M1.5V) = -1.432 +- 0.019 ; non-standard GJ 526 (Pecaut13)
=> adopt BCv(M1.5V) = -1.50 [updated 11/3/2019; BC_K=2.60, V-K=4.10]

BC_K(M1.5V) = 2.541 ; smoothed trend over M0V-M9V for M1V
BC_Ks(M1.5V)= 2.596 ; Mann15 for V-J=3.265
BC_Ks(M1.5V)= 2.603 ; Morrell19 trend for G-Ks=3.27
BC_K(M1.5V) = 2.613 +- 0.021 ; non-stan GJ 526 (Pecaut13) 
BC_K(M1.5V) = 2.655 +- 0.026 ; sec. stan. GJ 880 (Pecaut13)
=> adopt BC_K(M1.5V) = 2.60 [updated 11/3/2019]

Mv(M1.5V)   =  9.14 ; Kirkpatrick94
Mv(M1.5V)   = 9.19 ; pri. stan. GJ 205 (metal-rich)
Mv(M1.5V)   = 9.26 ; exemplar GJ 134 = HD 275122 
Mv(M1.5V)   = 9.49 ; sec. stan. GJ 880 = HD 216899 (metal-rich)
Mv(M1.5V)   = 9.62 ; exemplar GJ 366 = Ross 434 
Mv(M1.5V)   = 9.78 ; EEM fit to Jao16 data for V-Ks=4.10
Mv(M1.5V)   = 9.89 ; Finch14 calibration for V-Ks=4.10
Mv(M1.5V)   = 9.91 ; JohnsonApps09 calibration for V-Ks=4.10
Mv(M1.5V)   = 9.94 ; Dieterich14 calibration for V-Ks=4.12
Mv(M1.5V)   = 10.02 ; Henry04 calibration for V-Ks=4.10 
=> adopt Mv(M1.5V) = 9.90 [updated 11/3/2019; V-Ks=4.10, M_Ks=5.80]

M_Ks(M1.5V) = 5.82 ; Dieterich14 calibration for V-Ks=4.12
M_Ks(M1.5V) = 5.82 ; EEM calib for Winters15 data for V-Ks=4.12
M_Ks(M1.5V) = 5.81 ; JohnsonApps09 calibration for V-Ks=4.10
M_Ks(M1.5V) = 5.79 ; Finch14 calibration for V-Ks=4.10 
M_Ks(M1.5V) = 5.68 ; Jao16 calibration for V-Ks=4.10
M_Ks(M1.5V) = 5.64 ; exemplar GJ 366 = Ross 434 
M_Ks(M1.5V) = 5.34 ; sec. stan. GJ 880 = HD 216899 
M_Ks(M1.5V) = 5.15 ; exemplar GJ 134 = HD 275122 
=> adopt M_Ks(M1.5V) = 5.80 [updated 11/3/2019; V-Ks=4.10, Mv=9.90]

logL(M1.5V) = -1.473 ; Morrell19 trend for logL for M_Ks=5.82
logL(M1.5V) = -1.464 ; M_Ks=5.80, BC_Ks=2.60, MBbol = 8.40
=> adopt logL(M1.5V) = -1.464 [updated 11/3/2019]
=> adopt Mbol(M1.5V) =  8.400 [updated 11/3/2019]

Rad(M1.5V) = 0.566+-0.002   Rsun ; pri. stan. GJ 205 = HD 36395 (Rabus19) [metal rich]
Rad(M1.5V) = 0.574+-0.004   Rsun ; pri. stan. GJ 205 = HD 36395 (Yee17) [metal rich]
Rad(M1.5V) = 0.549          Rsun ; sec. stan. GJ 880 = HD 216899 [metal-rich]
Rad(M1.5V) = 0.548+-0.005   Rsun ; sec. stan. GJ 880 = HD 216899 (Yee17) [metal-rich]
Rad(M1.5V) = 0.4979+-0.0026 Rsun ; Boyajian12b (N=4)
Rad(M1.5V) = 0.483          Rsun ; Rabus19 trend for Teff=3640K
Rad(M1.5V) = 0.4743         Rsun ; Mann15 trend M_Ks=5.80, [Fe/H]=0.0
Rad(M1.5V) = 0.4738         Rsun ; logL=-1.464, Teff=3610K
Rad(M1.5V) = 0.3874+-0.0023 Rsun ; deprecated standard GJ 15A (Boyajian12)
=> adopt Rad(M1.5V) = 0.474 Rsun [updated 4/9/2020]

Mass(M1.5V) =  0.405+-0.008 Msun ; pri. of GJ22AC, unresolved SpT=M1.5V (Benedict16)
Mass(M1.5V) = 0.462 Msun ; Benedict16 calib. for Mv=9.94
Mass(M1.5V) = 0.471 Msun ; Mann18 calib. for M_Ks=5.80
Mass(M1.5V) =  0.490 Msun ; Delfosse00 calib. for M_Ks=5.80
Mass(M1.5V) = 0.531 Msun ; Benedict16 calib. for M_Ks=5.80
Mass(M1.5V) =  0.586+-0.007 Msun ; GJ570B (Benedict16)
Mass(M1.5V) =  0.600+-0.006 Msun ; GU Boo B (Benedict16)
Mass(M1.5V) =  0.610 Msun ; Torres10 calib. for Mv=9.94
=> adopt Mass(M1.5V) = 0.47 Msun [updated 11/3/2019]

# No Standard
Boeshaar85 does not list an M1.5V standard.

# Primary Standard

GJ 205 = HD 36395 = LHS 30
  M1V: JM53(non-stan.,"dM1")
 *M1.5Ve: Boeshaar76,KeenanMcNeil76(stan),Keenan85,Corbally86(stan,Keenan80),Keenan88,Kirkpatrick91(pri),Hawley97,Keenan99,Houk99,Henry02,Reid04,Mann15
  M2.33: Terrien15

  Excellent recent agreement on type, and has interferometric diameter
  and Teff estimates. Appears to be metal-rich [Fe/H] ~
  +0.4. Segransan03 VLTI study reports: M = 0.631+-0.031 Msun,
  R=0.702+-0.063 Rsun, Teff = 3520+-170 K, logg=4.54+-0.06
  dex. KeenanMcNeil76 do not list Gl 205 as a standard in their Table
  3, however they do show it as a M2 dwarf in their Plate
  19. V=7.966+-0.011(Mermilliod91), V=7.960(Landolt83),
  B-V=1.474+-0.009(Mermilliod91), B-V=1.474(Landolt83),
  U-B=1.213+-0.024(Mermilliod91), U-B=1.231(Landolt83),
  V-R=0.985(Landolt83), R-I=1.095(Landolt83), V-I=2.076(Landolt83).
  Unfortunately all 2MASS photometry is saturated, but Mann15 fits
  synthetic 2MASS magnitudes: J=4.796+-0.017, H=4.123+-0.017,
  Ks=3.856+-0.019. Teffs: 3520+-170K(Segransan03),
  3708K(Prugniel07#2), 3719K(Prugniel07#1), 3732+-56K(Ramirez05),
  3737K(Alonso96), 3760K(Wolff05), 3801+-60K(Mann15),
  3835+-69K(Rabus19), 3850+-22K(Newton15#1), 3872K(Newton15#2),
  4012+-106K(Rojas-Ayala12) => <Teff> = 3760K.
  R=0.5735+-0.044Rsun(Newton14), R=0.581+-0.019Rsun(Mann15),
  logL=-1.1905+-0.0094(Newton14), M=0.633+-0.063Msun(Mann15),
  [Fe/H]=0.49+-0.08(Mann15). plx=175.4287+-0.0672mas(GaiaDR2).
  Mv=9.19+-0.01(Mermilliod91,GaiaDR2). Boyajian12 reports
  tetLD=0.943+-0.004mas. Boyajian12+GaiaDR2 => Rad = 0.578Rsun.
  Rabus19: tetLD=0.924+-0.003mas, fbol=(6.140+-0.400)e-8,
  Rad=0.566+-0.002Rsun, Teff=3835+-69K.  [Fe/H] =
  0.35+-0.17(RoyasAyala12), 0.43+-0.08(Gaidos14), 0.69(Terrien15,
  seems too high!), 0.49+-0.08(Mann15).

# Secondary Standard

GJ 880 = HD 216899 = BD+15_4733 = Ross 671
   M1.43: Terrien15(epoch#1)
  *M1.5V: Henry94,Hawley97,Henry02(stan),Reid04,Kirkpatrick12(KirkpatrickPhD),Lepine13,Mann15
   M1.78: Terrien15(epoch#2)
   M2: Vyssotsky56,Bidelman85
   M2.5V: Joy74
   
   V=8.672+-0.013(Mermilliod91), V=8.66(Weis93),
   B-V=1.512+-0.006(Mermilliod91), B-V=1.50(Weis93), V-R=1.06(Weis93),
   R-I=0.87(Weis93), U-B=1.175+-0.010(Mermilliod91),
   J=5.360+-0.020(2MASS), Ks=4.523+-0.016(2MASS),
   V-Ks=8.672-4.523=4.149+-0.021(Mermilliod91,2MASS). 2MASS H-band is
   flagged 'E'.  mbol=7.178+-0.020(Pecaut13). BC_Ks = mbol - Ks =
   7.178 - 4.523 = 2.655+-0.026.  BCv = mbol - V = 7.178 - 8.672 =
   -1.494+-0.024.  Teff = 3520K(Lepine13), 3720+-60K(Mann15#1),
   3731+-16K(Newton15#2), 3749+-76K(Newton15#2), 3759K(Alonso96),
   3760+-35K(Mann15#2), 3808+-70K(Ramirez05) => <Teff>=3750K.
   R=0.5490+-0.0180Rsun(Mann15), R=0.5477+-0.0048Rsun(Newton15),
   R=0.548+-0.005Rsun(Therrien15), M=0.5740+-0.0570Msun(Mann15),
   [Fe/H]=0.21+-0.08 (more Mann15 numbers),
   logL=-1.2856+-0.0049(Newton15). Boyajian12 reports
   tetLD=0.744+-0.004mas.
   plx=145.6107+-0.0388mas(GaiaDR2). Boyajian12+GaiaDR2 => Rad
   =0.549Rsun. Rad=0.548+-0.005Rsun(Yee17).  Metallicities are all
   over the place, but the star has a large radius and is probably
   metal-rich, as some recent results have been indicating - probably
   [Fe/H] ~ +0.1.: [Fe/H]= -1.50(Alonso96), -0.01+-0.09(Maldonado19),
   +0.026+-0.080(Hojjatpanah19), +0.06+-0.10(Yee17), +0.07(Neves13),
   +0.12+-0.16(Schweitzer19), +0.18+-0.11(Gaidos14),
   +0.20+-0.05(Lindgren17). Mv=9.488+-0.013(Mermilliod91,GaiaDR2),
   M_Ks=5.339+-0.016(2MASS,GaiaDR2).

# Tertiary Standard

GJ 526 = HD 119850 = StKM 2-980 = LHS 47
  M1: Gaidos14
  M1.4: Mann15
 *M1.5V: Bidelman85(M1.5),Henry94,Hawley97,Henry02(stan)
  M2V: Keenan85,Keenan88,Keenan89,GrayNstars,Newton14(near-IR)
  M3V: Joy74,Stephenson86

  Reasonable agreement between Henry, Hawley, and Mann, although
  notably Keenan and Newton place the type 0.5 later.  Colors and
  Teffs consistent with the other M1.5V standards.
  (B-V)=1.448+-0.017(Mermilliod91), V=8.460+-0.014(Mermilliod91),
  (U-B)=1.099+-0.023(Mermilliod91). 2MASS photometry, only K band is
  flagged as A quality: Ks=4.415+-0.017(2MASS). V-Ks = 8.460 - 4.415 =
  4.045. mbol=7.028+-0.013(Pecaut13).  BC_Ks = mbol - Ks = 7.028 -
  4.415 = 2.613+-0.021. Teffs: 3570+-16K(Pecaut13), 3618K(Boyajian12),
  3623K(Prugniel07), 3646+-34K(Newton14), 3650K(Woolf05),
  3664+-153K(vanBelle09), 3680K(Prugniel07#2), 3716+-125K(Newton14#2),
  3792+-92K(Gaidos14) => <Teff> = 3650K. [Fe/H]=-0.31+-0.08(Mann15),
  -0.18+-0.09(Gaidos14), [Fe/H]=-0.10, -0.33(Prugniel07, 2 values),
  [Fe/H] = -0.10+-0.07(Woolf05).  Star is apparently somewhat metal
  poor.

# Deprecated Standards

GJ 15A = BD+43_44A = GX And = HD 1326A
  M1V: JM53(non-standard),Hawley97,Reid04
 *M1.5V: GrayAtlas,Boeshaar94,Kirkpatrick94,Henry94(not standard),Henry02
  M2V: Keenan85,Keenan88,Keenan99,Sozetti02

  Keenan repeatedly classified GJ 15A as M2, but everyone else
  considers it M1 or M1.5. V=8.089+-0.017(Mermilliod91),
  B-V=1.567+-0.014(Mermilliod91),
  U-B=1.222+-0.026(Mermilliod91). Segranson03 VLTI study:
  M=0.414+-0.021 Msun, R=0.383+-0.02 Rsun, Teff = 3698+-95 K,
  logg=4.89+-0.06 dex.  fbol = (5.420+-0.044)e-8 erg/cm/s^2
  (Boyajian12), L = 0.02173+-0.00021 Lsun (Boyajian12), Teff=3563+-11
  K (Boyajian12), R = 0.3874+-0.0023 Rsun (Boyajian12). [Fe/H]=-0.36
  (Neves11). 2MASS photometry poor. 

GJ 570B = HD 131976
  M1.5V: Keenan85,Keenan88,GrayNstars
 *M1.0VJ: Henry02

GJ 570BC = LHS 386 = HD 131976 = BD-20 4123 = Lalande 27173BC
  M0.5: Bidelman85
  M1.0V: Walker83,Henry94(Kirkpatrick12),Hawley97,Henry02("joint"),Geballe02,Houdebine12(dM1)
 *M1V+M3:V: Kirkpatrick12
  M1.0V+M1.0V: Reid04
  M1.5V: Keenan85,Keenan89(stan),Gray06
  M1.5V+M3V: Pourbaix/SB9
  M2V: Vyssotsky56,Cowley67,Joy74,Stephenson86,Gaidos14,Newton14
  M2III: Houdebine10(prob. because of poor parallax)

  Unfortunately Keenan considered M1.5, but Henry considers M1. I
  deprecate the Keenan type as the Henry types have become modern
  standards. 0.0437" binary according to Tokovinin15, with
  delta(y)=1.6, and SB orbit from Forvielle99 (Period 308 days).  25"
  away from primary HR 5568 (HD 131977). Forveille99 splits the BC
  components, with M_J(B) = 6.213+-0.033, M_J(C) = 7.403+-0.039, and
  M_K(B) = 5.396+-0.033, M_K(C) = 6.576+-0.039, so delta(K) =
  1.18. Given this delta(mag), it likely that the companion is >2
  subtypes later, similar to what Pourbaix reports. Forvielle99
  section 4 discusses the IR photometry for the pair in more
  detail. Magnitudes are unresolved unless specifically stated:
  V=8.065(Koen10), B-V=1.494(Koen10), U-B=1.200(Koen10),
  V-Rc=0.990(Koen10), V-Ic=2.122(Koen10).
  Mass=0.586+-0.007Msun(Torres10), R=0.52+-0.05Rsun(Gaidos14).  Teffs:
  3454+-50K(Houdebine12), 3500+-100K(Torres10),
  3506K(Cenarro01,Sanchez-Blazquez06,Cenarro07), 3650K(Stelzer13),
  3788+-88K(Gaidos14) => 3506K. [Fe/H]=0.10+-0.13,
  0.12+-0.02(Newton14).  Note that GJ 570A appears to roughly solar
  metallicity. Forvielle99 derives dynamical masses of M(B) =
  0.586+-0.007 Msun, M(C) = 0.390+-0.005.

GJ 49 = G 243-052 = LHS 1179 = HIP 4872
  M1.5V: KeenanMcNeil76(stan),Garcia89,Hawley97
  M2V: Gunn83,Joy74,Vyossotsky43
 *M2+V: Gray03
  M1: Bidelman85(Kuiper)
  K5V: LjunggrenOja61(Jaschek64,Jaschek78),Sjogren64
  M3: Lee47

  Not sure why this star not used as an M1.5V standard after
  KeenanMcNeil76. vanLeeuwen07 plx = 100.40+-1.52 mas. V=9.552+-0.015
  (Mermilliod91), B-V=1.503+-0.005(Mermilliod91),
  U-B=1.21+-0.058(Mermilliod91). J=6.230+-0.021(2MASS),
  H=5.582+-0.024(Mermilliod91), Ks=5.371+-0.020(2MASS).

# Exemplars

GJ 908 = LHS 550 = BR Psc = HIP 117473 = Lal 46650
  M0V: Newton14(near-IR)
  M1V: Stephenson86,Henry94,Hawley97,Henry02
  M1V Fe-1: Keenan89
  M1.4: Mann15
 *M1.5V: Bidelman85(M1.5),Lepine13
  M2V: Vyssotsky43,JM53(non-stan),Cowley82(M2Ve),Torres06,Gaidos14
  M2.5Ve: Joy74
  M3: Lee47

  Type has mostly oscillated between ~M1 and ~M2 over the years.  :
  [Fe/H]=-0.95+-0.19, as does Mann15 [Fe/H]=-0.45+-0.08.
  V=8.983+-0.012(Mermilliod91), B-V=1.464+-0.028(Mermilliod91),
  U-B=1.104+-0.025(Mermilliod91), J=5.827+-0.023(2MASS),
  H=5.282+-0.031(2MASS),
  Ks=5.043+-0.020(2MASS). V-Ks=3.940(Mermilliod91,2MASS). mbol =
  7.503+-0.025 (JHK => Casagrande08 calib.) => BCv = -1.48, BC_K =
  2.46.  Plx = 167.29+-1.23 mas. Mv=10.10+-0.02(Mermilliod91,
  vanLeeuwen07), M_Ks=6.16+-0.03(2MASS,vanLeeuwen07).  This star was
  also modeled by Leggett96: flux = 2.50e-11 W/m^2, logL=-1.59,
  mbol=7.53, Mbol=8.74, BCv=-1.45, BC_K=2.48.  Teffs:
  3646+-60K(Mann15#1), 3700+-150K(Leggett96), 3704+-29K(Mann15),
  3712+-85K(Gaidos14) => adopt Teff=3700K. Nice to see the Leggett96
  and Casagrande08-derived mbol agree at the +-0.03 mag level!
  G=8.1496 0.0007, Bp-Rp=2.1050, Bp-G=1.0879, G-Rp=1.0170.

GJ 134 = HD 275122 = Wolf 1325 = LHS 1528 = HIP 15366 = 2MASS J03180742+3815081 = G 95-25 = G 78-31 = LTT 11082 
  K7: Cannon49
 *M1.5V: Joy74,Bidelman85(M1.5),Reid95/Hawley97(M1.5),Lurie13(M1.5),Mann15(M1.5)
  M2V: Vyssotsky46,Gaidos14(M2)
  M3: Lee47,Stephenson86(M3:)

  V=10.280(Mermilliod91), B-V=1.475(Mermilliod91),
  U-B=1.205(Mermilliod91).  Ks=6.164+-0.020(2MASS), V-Ks = 10.280 -
  6.164 = 4.116.  plx=62.5647+-0.0720mas(GaiaDR2).
  Mv=9.26(Mermilliod91,GaiaDR2).  M_Ks=5.146+-0.020(2MASS,GaiaDR2).
  G=9.4103 0.0006, Bp-Rp=2.1254, Bp-G=1.1107, G-Rp=1.0148.

GJ 366 = Ross 434 = LHS 2188 = HIP 47981 = G 252-44 = G 253-30 = LTT 12585 = NLTT 222468 = 2MASS J09464844+7602388
  M1: Lee47
 *M1.5V: Joy74,Bidelman85(M1.5),Reid95(M1.5),Lurie13(M1.5)
  M2V: Vyssotsky46,Gaidos14(M2)

  V=10.615+-0.015(Mermilliod91), V=10.64(Weis93),
  B-V=1.415+-0.015(Mermilliod91), B-V=1.40(Weis93), V-R=1.02(Weis93),
  R-I=0.87(Weis93), U-B=1.09+0.01(Mermilliod91),
  Ks=6.629+-0.024(2MASS), V-Ks=10.615 - 6.629 = 3.986.
  plx=63.3142+-0.0302mas. Mv = 9.623+-0.015 , M_Ks= 5.637+-0.024.
  G=9.7846 0.0007, Bp-Rp=2.1161, Bp-G=1.1053, G-Rp=1.0108.

LHS 2429 

LHS 1828 

G 242-48

BD+61 195

GJ 3098

GJ 87

tet Per B

2MASS J08175130+3107455

2MASS J14562809+1648342

GJ 625





# Other Stars

RECONS list shows GJ 887 (J2305-3551) as the nearest M1.5V star,
followed by GJ 15A (J0018+4401), & GJ 191 (J0511-4501).