M2V

Kirkpatrick(in GrayCorbally09) call Gl 411 the primary M2V
standard. It has very strong pedigree as it is considered M2V by
JohnsonMorgan53, Houk, Keenan, Kirkpatrick, Henry, Hawley, Reid.

As with the other mid-M types, there is a wide range of radii among
even the M2V standards and exemplars: approximately 0.39-0.52 Rsun. I
adopt the Mann15 calibration for M_Ks vs Radius for [Fe/H] (adopting
M_Ks=5.98) to guide estimation of the mean HRD point.

JM53 standard:       GJ 411 (HD 95735) - M2V (latest JM53 dwarf standard)
Houk75 standard:     GJ 411 (HD 95735) - M2V (primary standard)
Boeshaar76 standard: GJ 411 (=HD 95735) - M2 (Plate II standard)
KeenanMcNeil76 stan: GJ 250B - M2V (in Table 3)
		     GJ 411 - M2V (on Plate 19)
Keenan80 standard:   GJ 15 A (HD 1326)   - M2V
                     GJ 411 (=HD 95735)  - M2+V
Keenan83 standard:   GJ 15 A (=HD 1326)  - M2V
	             GJ 411 (=HD 95735)  - M2+V
		     GJ 526 (=HD 119850) - M2-V
Keenan85 standard:   GJ 15A (=HD 1326)   - M2V
                     GJ 411 (=HD 95735)  - M2+V 
Turnshek85 standard: GJ 411 (=HD 95735)  - dM2+
Boeshaar85 standard: GJ 745B             - M2V
Keenan88 standard:   GJ 15A (= HD 1326)  - M2V 
                     GJ 526 (=HD 119850) - M2V
                     GJ 411 (= HD 95735) - M2+V
Keenan89 standard:   GJ 15A (=HD 1326)   - M2V
                     GJ 526 (=HD 119850) - M2V
                     GJ 411 (=HD 95735)  - M2+V
Kirkpatrick91 stan:  GJ 411 (=HD 95735)  - M2V (primary standard)
                     GJ 382 (BD-3_2870)  - M2V (primary standard)
 		     GJ 220 (Ross 59)    - M2V (secondary standard)
		     GJ 22AC (BD+66_34)  - M2V (secondary standard)
		     GJ 806 (G 209-41)   - M2V (secondary standard)
Kirkpatrick94 stan:  GJ 220 (Ross 59) 	 - M2V
	      	     GJ 806 (G 209-41) 	 - M2V
Hawley02 standard:   GJ 220 (Ross 59)    - M2V 
Henry02 standards:   GJ 411 (=HD 95735)  - M2.0V 
 		     GJ 382 (BD-3_2870)  - M2.0V 
 		     GJ 393              - M2.0V 
		     GJ 22AC (BD+66_34)  - M2.0VJ ("J" = joint/binary)
GrayAtlas standard:  GJ 411 (HD 95735)   - M2V
GrayNstars standard: HD 1326             - M2V
	   	     GJ 526              - M2V
 	   	     GJ 382              - M2+V
Kirkpatrick10        GJ 91               - M2V 
Pecaut13 standard:   GJ 411              - M2+V
Kirkpatrick16 stan:  GJ 411 (=HD 95735)  - M2V  

GrayAtlas shows M2-type standards, but does not list the names. I
emailed Gray and he said that the standards were: GJ 411 (M2V), chi
Peg (M2+III), HD 10465 (M2Ib), mu Cep (M2-Ia).

Skiff08 flags one star as M2V MK standard: HD 119850 = GJ 526 (Keenan89).

In Kirkpatrick12 census of systems within 8 pc, the only M2V stars are
GJ 411, GJ 693, GJ 393, GJ 382.

Joy74 M2V stars appear to be approximately M1+V (~M1.2+-0.7 subtypes)
on the Kirkpatrick91 system.

<B-V>(M2V) =  1.380 ; Crawford76
(B-V)(M2V) = 1.460  ; exemplar GJ 832 = HD 204961 
<B-V>(M2V) =  1.47  ; Fitzgerald70
<B-V>(M2V) = 1.489  ; 8 Gray03/06 (+-0.023 sem, +-0.052 stdev)
(B-V)(M2V) =  1.49  ; SchmidtKaler82
(B-V)(M2V) = 1.494  ; ter. stan. GJ 91 
(B-V)(M2V) =  1.50  ; Leggett92 "young disk"
(B-V)(M2V) = 1.50   ; exemplar GJ 2066
(B-V)(M2V) = 1.50   ; exemplar GJ 9440 
(B-V)(M2V) = 1.50   ; ter. stan. GJ 220
(B-V)(M2V) = 1.500  ; median SIMBAD M2V d<25pc (N=93)
(B-V)(M2V) = 1.503  ; sec. stan. GJ 382
(B-V)(M2V) = 1.506  ; nearby M2V star GJ 393 (8 pc sample)
(B-V)(M2V) = 1.508  ; prim. stan. GJ 411
(B-V)(M2V) = 1.510 (+-0.007 sem,+-0.038 stdev); med. for 23 ARICNS M2V stars
<B-V>(M2V) =  1.51  ; ShayaOlling11
<B-V>(M2V) =  1.52  ; Johnson66
(B-V)(M2V) =  1.52  ; Bessell91 "old disk"
(B-V)(M2V) = 1.523  ; Koen10 median d<25pc M2V
<B-V>(M2V) =  1.53  ; Bessell79
(B-V)(M2V) = 1.55   ; exemplar GJ 3809 
(B-V)(M2V) = 1.570  ; sec. stan. GJ 745B
=> adopt (B-V)(M2V) = 1.505 [updated 8/13/2020] 

<U-B>(M2V) = 1.17 ; Johnson66

<V-R>(M2V) = 1.50 ; Johnson66
(V-R)(M2V) = 1.00 ; Bessell91 "old disk"

(R-I)(M2V) = 1.16 ; Bessell91 "old disk"

(V-Ic)(M2V) = 2.05  ; Leggett92 "young disk"
<V-Ic>(M2V) = 2.078 (+-0.122 sem, +-0.291 stdev; Gray01/03/06 N=8)
(V-Ic)(M2V) = 2.16  ; Bessell91 "old disk"
(V-Ic)(M2V) = 2.165 ; ter. stan. GJ 91 
<V-Ic>(M2V) = 2.19  ; Bessell79
(V-Ic)(M2V) = 2.25  ; Hawley96
<V-Ic>(M2V) = 2.257 (+- 0.135 sem, +-0.235 stdev; N=3 standards)

<V-I>(M2V)  = 2.69 ; Johnson66

<R-Ic>(M2V) = 0.76 ; Bessell79

(G-J)(M2V)   = 2.396 ; Bentley18
(G-Ks)(M2V)  = 3.246 ; Bentley18
(Ks-W2)(M2V) = 0.259 ; Bentley18
(W1-W2)(M2V) = 0.102 ; Bentley18

(Ks-W1)(M2V) = 0.157 ; Bentley18
(Ks-W1)(M2V) = 0.145 ; fit to Winters15 data for V-Ks=4.23
(Ks-W1)(M2V) = 0.115 ; Best18
(Ks-W1)(M2V) = 0.110 ; Avenhaus12 for V-Ks=4.23
=> adopt (Ks-W1)(M2V) = 0.14 [updated 12/29/2019]


<V-J>(M2V)  = 3.37 ; Johnson66
<V-J>(M2V)  = 3.418 (+- 0.033 sem, +-0.057 stdev; N=3 standards)
<V-J>(M2V)  = 3.52  (+-0.34 stdev) ; Lepine12

<V-K_CIT>   =  4.05 ; Beuermann06
(V-K_CIT)   =  4.05 ; Leggett92 "young disk"
(V-K)(M2V)  =  4.11 ; Bessell91 "old disk"
(V-Ks)(M2V) = 4.13  ; pri. stan. GJ 411 (uncertainty ~+-0.1 mag)
(V-Ks)(M2V) = 4.171 ; exemplar GJ 832 = HD 204961 
(V-Ks)(M2V) = 4.207 ; ter. stan. GJ 220
(V-Ks)(M2V) = 4.225 ; ter. stan. GJ 91 
(V-Ks)(M2V) = 4.243 ; ter. stan. GJ 745B
(V-Ks)(M2V) = 4.245 ; sec. stan. GJ 382
(V-Ks)(M2V) = 4.245 ; exemplar GJ 3809 
(V-Ks)(M2V) = 4.267 ; exemplar GJ 9440 
<V-K>(M2V)  =  4.27 ; Johnson66
(V-Ks)(M2V) = 4.284 ; exemplar GJ 2066
(V-K)(M2V)  =  4.3  ; Hawley96
(V-Ks)(M2V) =  4.344 ; deprecated stan. GJ 393
=> adopt (V-Ks)(M2V) = 4.23  *** [updated 11/1/2019]
=> adopt (U-B)(M2V)  = 1.169
=> adopt (V-I)(M2V)  = 2.166
=> adopt (V-R)(M2V)  = 0.999
=> adopt (R-I)(M2V)  = 1.167
=> adopt (V-J)(M2V)  = 3.396
=> adopt (V-H)(M2V)  = 3.996
=> adopt (H-Ks)(M2V) = 0.234
=> adopt (J-H)(M2V)  = 0.600
=> adopt (I-Ks)(M2V) = 2.067
=> adopt (K-W1)(M2V) = 0.109
=> adopt (G-V)(M1.5V)  = -0.872 [last updated 6/1/2018]

<J-K_CIT>(M2V) = 0.86 ; Beuermann06

<H-K_CIT>(M2V) = 0.20 ; Beuermann06

(Bp-Rp)(M2V)=  2.1045 ; HD_217987    M2V
(Bp-Rp)(M2V)= 2.1858 ; GJ_220       ter. stan.
(Bp-Rp)(M2V)= 2.1912 ; GJ_9440      exemplar
(Bp-Rp)(M2V)=  2.2149 ; CD-31_9113   M2V
(Bp-Rp)(M2V)= 2.2296 ; GJ_91        ter. stan.
(Bp-Rp)(M2V)= 2.2315 ; GJ_3809      exemplar 
(Bp-Rp)(M2V)= 2.2338 ; GJ_382       sec. stan.
(Bp-Rp)(M2V)= 2.2437 ; GJ_832       exemplar
(Bp-Rp)(M2V)=  2.25  ; Kiman19 
(Bp-Rp)(M2V)=  2.2741 ; V*_FK_Aqr    M2V
(Bp-Rp)(M2V)= 2.2939 ; GJ_745B      ter. stan.
(Bp-Rp)(M2V)= 2.2976 ; GJ_2066      exemplar 
(Bp-Rp)(M2V)=  2.3002 ; G_202-48     M2V
(Bp-Rp)(M2V)=  2.3040 ; BD+01_2447   M2V
(Bp-Rp)(M2V)=  2.3095 ; HD_285968    M2V
(Bp-Rp)(M2V)=  2.3115 ; BD+66_34A    M2V
(Bp-Rp)(M2V)=  2.8468 ; CD-48_11837  M2V
=> adopt (Bp-Rp)(M2V) = 2.23 [last updated 11/18/2020]

(G-Rp)(M2V) =  1.0109 ; HD_217987    M2V
(G-Rp)(M2V) = 1.0283 ; GJ_220       ter. stan.
(G-Rp)(M2V) =  1.0344 ; GJ_9440      exemplar 
(G-Rp)(M2V) =  1.0461 ; CD-31_9113   M2V
(G-Rp)(M2V) = 1.0537 ; GJ_91        ter. stan.
(G-Rp)(M2V) = 1.0570 ; GJ_382       sec. stan.
(G-Rp)(M2V) = 1.0615 ; GJ_745B      ter. stan.
(G-Rp)(M2V) =  1.0616 ; GJ_832       exemplar 
(G-Rp)(M2V) =  1.0630 ; GJ_2066      exemplar
(G-Rp)(M2V) = 1.063  ; color trend M0V-M9V 
(G-Rp)(M2V) =  1.0649 ; V*_FK_Aqr    M2V
(G-Rp)(M2V) =  1.0679 ; G_202-48     M2V
(G-Rp)(M2V) =  1.0704 ; BD+01_2447   M2V
(G-Rp)(M2V) =  1.0763 ; HD_285968    M2V
(G-Rp)(M2V) =  1.0818 ; BD+66_34A    M2V
(G-Rp)(M2V) =   1.09  ; Kiman19  
(G-Rp)(M2V) =  1.2196 ; CD-48_11837  M2V
=> adopt (G-Rp)(M2V) = 1.06 [last updated 11/18/2020]
=> adopt (Bp-G)(M2V) = 1.17 [last updated 11/18/2020; Bp-Rp=2.23, G-Rp=1.06]

(Bp-G)(M2V) = 1.16 ; Kiman19 

(G-V)(M2V) = -0.9767 ; GJ_745B
(G-V)(M2V) = -0.944  ; polynomial fit to SIMBAD d<25pc M dwarfs
(G-V)(M2V) = -0.933  ; median M2V d<60pc (N=170)
(G-V)(M2V) = -0.9247 ; sec. stan. GJ_382 
(G-V)(M2V) = -0.923  ; trend Kervella19 d<25pc for V-Ks=4.23
(G-V)(M2V) = -0.9197 ; ter. stan. GJ 91 
(G-V)(M2V) = -0.8924 ; ter. stan. GJ_220
=> adopt (G-V)(M2V) = -0.925 [updated 11/1/2020]
=> adopt (G-Ks)(M2V) = 4.23 + -0.925 = 3.305 [updated 12/10/2020]

(g-r)(M2V) = 1.43 ; Covey07

(r-i)(M2V) = 0.957 (+-0.05 rms) ; West05 fit for (V-Ic)=2.166
(r-i)(M2V) = 1.00  (+-0.13 rms) ; West08


(i-z)(M2V) = 0.55 (+-0.08; rms) ; West08

(z-J)(M2V) = 1.31  (+-0.17  rms) ; West08
(z-J)(M2V) = 1.386 (+-0.028 rms) ; poly fit to d<100pc GCNS for G-Ks=3.305


Teff(M2V) =  3414 K ; Morrell19 <Teff> for stars w/i +-0.05 mag of M_Ks=5.98
Teff(M2V) =   3464 +- 15 K ; Boyajian12b (N=1) 
Teff(M2V) =   3477 K ; EEM N=39 Teffs
Teff(M2V) =   3481 +- 14 K ; Pecaut13 (pri. stan. GJ 411)
Teff(M2V) =  3482 K ; ter. stan. GJ 745B 
Teff(M2V) =   3496 K ; mean photometric Teff
Teff(M2V) =    3500 K ; Bessell74 (blackbody Teffs from Veeder74)
Teff(M2V) =  3500 K ; Rajpurohit13 (N=5)
Teff(M2V) =  3518 +- 57 K ; Lepine12
Teff(M2V) =  3520 K ; exemplar GJ 2066
Teff(M2V) =  3553 K ; Passegger18 median Teff for CARMENES M2.0V(N=37)
Teff(M2V) = 3560 K ; Rad=0.4468Rsun & Mann15 calib. for M_Ks=5.98, [Fe/H]=0.0
Teff(M2V) =  3561 K ; RojasAyala12(mean N=15 M2V stars)
Teff(M2V) =  3570 K ; pri. stan. GJ 411 
Teff(M2V) =  3570 K ; ter. stan. GJ 91
Teff(M2V) =  3577 K ; deprecated stan. GJ 22A (Dieterich21)
Teff(M2V) =  3590 K ; empirical L-R relation, for logL=-1.540
Teff(M2V) =  3591 K ; exemplar GJ 3809 
Teff(M2V) =  3594 K ; Boyajian12 calibration V-K=4.24,[Fe/H]=0.0
Teff(M2V) =  3599 +- 49 K  ; vanBelle09
Teff(M2V) =  3615 K ; sec. stan. GJ 382
Teff(M2V) =  3620 K ; smooth Teff(SpT) trend
Teff(M2V) =    3720 K ; Bertone04(NextGen)
Teff(M2V) =  3791 K ; ter. stan. GJ 220 (only two estimates)
=> adopt Teff(M2V) = 3560 K (logT = 3.551) [updated 4/9/2020]

BCv(M2V) =   -2.124 mag ; Flower96(Teff=3550K)
BCv(M2V) =    -1.76  mag ; Schmidt-Kaler82(BCv=-1.89 + 0.13 offset)
BCv(M2V) =  -1.753 mag ; sec. stan. GJ 382 (see notes below)
BCv(M2V) = -1.705 mag ; exemplar GJ 176 = HD 285968 (calc. using Rabus19)
BCv(M2V) =  -1.689 mag ; ter. stan. GJ 745B
BCv(M2V) = -1.688 mag ; exemplar GJ 176 = HD 285968 (calc. using Mann15)
BCv(M2V) = -1.674 mag ; Casagrande18(Teff=3570K,logg=4.5)
BCv(M2V) = -1.67  mag ; BC_K=2.56, V-K=4.23
BCv(M2V) = -1.662 mag ; exemplar GJ 9440 
BCv(M2V) =  -1.625 +- 0.019 ; pri. stan. GJ 411 (Pecaut13)
BCv(M2V) = -1.624 mag ; Mann15(V-J=3.406)
BCv(M2V) =    -1.61  mag ; Bessell91("old disk"; BCv = (V-I)-BC_I)
BCv(M2V) =    -1.547  mag ; Bessell98(ATLAS9,logg=4.5,Teff=3550K)
BCv(M2V) =  -1.53  mag ; pri. stan. GJ 411 (Leggett96)
BCv(M2V) =  -1.463 mag ; EEM fit to Casagrande08 for Teff=3500K
BCv(M2V) =  -1.485 +- 0.020 ; non-standard GJ 887 (Pecaut13)
BCv(M2V) =  -1.485 mag ; exemplar GJ 832 = HD 204961 
BCv(M2V) =    -1.37  mag ; Bertone04(NextGen)
=> adopt BCv(M2V) = -1.62 mag [updated 11/3/2019; BC_Ks=2.61, V-Ks=4.23]

BC_K(M2V) = 2.49  mag ; sec. stan. GJ 382 (see notes below)
BC_K(M2V) = 2.55  mag ; ter. stan. GJ 752B
BC_K(M2V) = 2.58  mag ; pri. stan. GJ 411 (Leggett96)
BC_Ks(M2V)= 2.614 mag ; Morrell19 trend for G-Ks=3.31
BC_Ks(M2V)= 2.619 mag ; Mann15 for V-J=3.396
BC_K(M2V) = 2.63  mag ; Leggett01 (J-K=0.834)
BC_Ks(M2V)= 2.633 mag ; exemplar GJ 176 = HD 285968
BC_Ks(M2V)= 2.682 mag ; exemplar GJ 832 = HD 204961 
=> adopt BC_K(M2V) = 2.61 mag [updated 11/3/2019]

Mv(M2V) =  11.06 ; ter. stan. GJ 752B
Mv(M2V) =   10.56 ; Henry94
Mv(M2V) =  10.47 ; pri. stan. GJ 411
Mv(M2V) =  10.41 ; deprecated stan. GJ 393
Mv(M2V) =  10.32 ; deprecated stan. GJ 22A (Dieterich21)
Mv(M2V) ~  10.3  ; (see Fig. 9 of Riedel+2010 for V-K=4.23)
Mv(M2V) =  10.30 ; candidate stan. GJ 2066
Mv(M2V) =  10.20 ; EEM calib for Winters+2015 data for V-K=4.23
Mv(M2V) = 10.21 ; M_Ks=5.98, V-Ks=4.23
Mv(M2V) = 10.21 ; V-Ks=4.23 => Finch14
Mv(M2V) =  10.23 ; JohnsonApps09 calibration for V-K=4.23
Mv(M2V) =  10.23 ; Koen10 d<25pc median M2V
Mv(M2V) =  10.18 ; median SIMBAD M2V d<25pc (N=93)
Mv(M2V) =   10.16 ; Kirkpatrick94
Mv(M2V) =  9.98  ; V-Ks=4.23 => EEM fit to Reid CNS3 data 
Mv(M2V) =  9.835 ; ter. stan. GJ 91 
Mv(M2V) =    9.94 ; Wegner07
Mv(M2V) =  9.78 ; sec. stan. GJ 382
Mv(M2V) =  9.51 ; non-stan. GJ 9440
Mv(M2V) =  9.40 ; ter. stan. GJ 220
=> adopt Mv(M2V)   = 10.21 mag [updated 11/3/2019]  (V-Ks=4.23, M_Ks=5.98)
=> adopt M_G(M2V)  =  9.285 mag [updated 12/10/2020] (Mv=10.21, G-V=-0.925)
=> adopt M_Ks(M2V) =  5.98 mag [updated 12/10/2020] (Mv=10.21, V-Ks=4.23)

M_G(M2V) =   8.15557 ; HD 115953                   
M_G(M2V) =   8.73432 ; V* SZ UMa                   
M_G(M2V) =   8.73736 ; BD+25 3173                  
M_G(M2V) =   8.89721 ; V* AN Sex                    
M_G(M2V) =   8.93085 ; HD 119850                    
M_G(M2V) =   8.93794 ; HD 217987                    
M_G(M2V) =   9.10368 ; CD-31 9113
M_G(M2V) =  9.227    ; SIMBAD d<20pc trend for V-Ks=4.23
M_G(M2V) = 9.285    ; Mv=10.21, G-V=-0.925 
M_G(M2V) =  9.346    ; trend d<10pc SIMBAD
M_G(M2V) =  9.35     ; Kiman19 
M_G(M2V) =  9.45713  ; V* GX And                    
M_G(M2V) =  9.49187  ; HD 225213                    
M_G(M2V) =  9.54783  ; BD+66 34A                   
M_G(M2V) =  9.54953  ; BD+43 2796                  
M_G(M2V) =  9.6387   ; L 32-9                        
M_G(M2V) =   10.0634 ; HD 349726                    
M_G(M2V) =   10.4669 ; L 98-59                     
M_G(M2V) =   10.5414 ; Ross 695

M_Ks(M2V) =  6.81  ; ter. stan. GJ 745B
M_Ks(M2V) =  6.19  ; deprecated stan. GJ 22A (Dieterich21)
M_Ks(M2V) =  6.065 ; depreciated stan. GJ 393
M_Ks(M2V) =  6.07  ; V-K=4.23, Mv=10.30
M_Ks(M2V) =  6.013 ; candidate stan. GJ 2066 
M_Ks(M2V) =  5.999 ; V-K=4.23 => JohnsonApps2009 calibration
M_Ks(M2V) = 5.983 ; V-K=4.23 => Finch14 calibration
M_Ks(M2V) = 5.973 ; V-K=4.23 => EEM fit to Winters+2015 data
M_Ks(M2V) =  5.748 ; V-K=4.23 => EEM fit to Reid CNS3 data
M_Ks(M2V) =  5.610 ; ter. stan. GJ 91
M_Ks(M2V) =  5.54  ; sec. stan. GJ 382
M_Ks(M2V) =  5.245 ; non-stan. GJ 9440 
M_Ks(M2V) =  5.19  ; ter. stan. GJ 220

logL(M2V) = -1.315 dex ; sec. stan. GJ 382
logL(M2V) = =1.543 dex ; Morrell19 trend for logL for M_Ks=5.98
logL(M2V) = -1.540 dex ; M_Ks=5.98, BC_Ks=2.61 => Mbol = 8.590
logL(M2V) = -1.66  dex ; pri. stan. GJ 411 (Leggett96)
=> adopt logL(M2V) = -1.540 dex [updated 11/3/2019]
=> adopt Mbol(M2V) =  8.590 mag [updated 11/3/2019]

Mass(M2V) =  0.403 Msun ; pri. stan. GJ 411 (Segransen03)
Mass(M2V) =  0.405 Msun ; deprecated stan. GJ 22A (Dieterich21)
Mass(M2V) = 0.428 Msun ; Benedict16 calibration for Mv=10.21
Mass(M2V) = 0.443 Msun ; Mann18 calibration for M_Ks=5.98
Mass(M2V) =  0.455 Msun ; Delfosse00 calibration for M_Ks=5.98
Mass(M2V) =  0.479 Msun ; Eker15 calibration for logL=-1.574
Mass(M2V) =  0.49  Msun ; EEM logL vs. Mass fit for binaries (logL=-1.57)
Mass(M2V) = 0.499 Msun ; Benedict16 calibration for M_Ks=5.98
Mass(M2V) =  0.593 Msun ; Mv=10.23 => Torres10 calibration
=> adopt Mass(M2V) = 0.44 Msun [updated 11/3/2019]

Rad(M2V) = 0.376+-0.018   Rsun ; deprecated stan. GJ 22A (Dieterich21) [Fe/H]=-0.19
Rad(M2V) = 0.3924+-0.0033 Rsun ; Boyajian12b (N=1, presumably GJ411
Rad(M2V) = 0.392+-0.003   Rsun ; pri. stan. GJ 411 (Yee17)
Rad(M2V) = 0.435+-0.005   Rsun ; exemplar GJ 892 (Rabus19)
Rad(M2V) = 0.4464         Rsun ; logL=-1.540, Teff=3560K
Rad(M2V) = 0.4468         Rsun ; Mann15 trend M_Ks=5.98, [Fe/H]=0.0
Rad(M2V) = 0.461          Rsun ; Rabus19 trend for Teff=3590K
Rad(M2V) = 0.522+-0.019   Rsun ; sec. stan. GJ 382 (Yee17) 
=> adopt Rad(M2V) = 0.446 Rsun [updated 4/9/2020]

# Primary Standards

GJ 411 = HD 95735 = Lalande 21185 = LHS 37 (J1103+3558)
  M1.9: Mann15 
 *M2V: JM53,Abt68,Houk,Boeshaar76(stan),KeenanMcNeil76(stan; plate 19 & 21),Kirkpatrick91(pri),Kirkpatrick93,Kirkpatrick94,Henry94,Boeshaar94,Hawley97,Henry02,Reid04
  M2+V: Turnshek85(stan;dM2+),Keenan85,Keenan88,Keenan89,Keenan99,Pecaut13
  M2.5V: KeenanMcNeil76(stan; Table 3)

  The fourth nearest M dwarf (plx=392.64+-0.67mas; vanLeeuwen07).
  KeenanMcNeil76 call it a M2V standard on their Plates 19 and 21, but
  a M2.5V standard in Table 3. Saturated in 2MASS (mags of ~0.3 mag
  precision quoted). [Fe/H] = -0.2 (Zboril98),
  [Fe/H]=-0.41+-0.10(Yee17), [Fe/H]=-0.38+-0.08(Mann15). V=7.49(HIP),
  V=7.498+-0.013(Mermilliod91), B-V=1.502+-0.014(HIP),
  B-V=1.508+-0.014(Mermilliod91), U-B=1.124+-0.015(Mermilliod91),
  V-I=2.07+-0.02(HIP), V-I=2.16(Platais03), R-I=1.14(Delfosse98),
  J=4.09+-0.10(Reid04), Ks=3.35+-0.10(Reid04),
  K=3.36(Leinert97). V-J=3.40+-0.10(HIP & Reid04) (V-Ks)=4.13(HIP &
  Leinert97). The star is in the 2MASS catalog twice at slightly
  different epochs (~8" apart), but the photometry is
  poor. Mv=10.468+-0.014(Mermilliod91 V & vanLeeuwen07 plx).
  Leggett96 derives: 1.08e-10 W/m^2, logL=-1.66, mbol=5.94, Mbol=8.92,
  BCv=-1.53, BC_K=2.58. Pecaut13 derives mbol=5.873+-0.015, hence BCv
  = mbol - V = 5.873 - 7.498 = -1.625. Teffs: 3400K(ReidHawley05),
  3429K(Mould78), 3467K(Casagrande08), 3481+-14K(Pecaut13),
  3500K(Leggett96), 3510K(Tsuji96), 3510+-150K(Woolf05),
  3526K(RojasAyala12), 3532+-17K(Newton15), 3532+-85K(Newton15#2),
  3563K(Mann15), 3570+-42K(Segrensan03), 3593+-60K(vanBelle09),
  3600K(Prugniel07#1), 3620K(Zboril98), 3637+-32K(Mann15#2),
  3665K(Prugniel07#2), 3739K(LeBorgne03), 3828K(Alonso96),
  3837+-90K(Ramirez05) => adopt Teff = 3570K.  Segrensan03 VLTI study
  reports M = 0.403+-0.02 Msun, logg = 4.85+-0.03 dex. Radius:
  0.393+-0.008Rsun(Segransan03), 0.395+-0.013(vanBelle09),
  0.392+-0.003Rsun(Yee17). Inexplicably, vanBelle09 assumes that the
  star suffers from Av=0.151+-0.011 mag of interstellar extinction,
  which seems odd since the star has parallax 392.64+-0.67 mas (van
  Leeuwen07), i.e. it is one of the nearest stars to the Sun.
  Boyajian12 reports tetLD=1.432+-0.013mas. Boyajian12+GaiaDR2=>
  Rad=0.392 Rsun.

# Secondary Standards

GJ 382 = BD-03 2870 = DO 2904
  M0: Lee47
  M1V: Stephenson86
  M1.5V: Hawley97
 *M2V: Vyssotky56,Boeshaar76,Cowley82,Kirkpatrick91(pri),Henry02,Gaidos14(M2)
  M2+V: GrayNstars(stan)

  V=9.26(HIP), V=9.263+-0.019(Mermilliod91), B-V=1.487+-0.016(HIP),
  B-V(Mermilliod91)=1.503+-0.013, B-V=1.501+-0.003(Koen02),
  U-B=1.182+-0.018(Mermilliod91), U-B=1.184+-0.016(Koen02),
  V-I=2.18+-0.00(HIP), V-R=0.998+-0.007(Koen02),
  V-I=2.171+-0.004(Koen02), J=5.888+-0.021(2MASS), H=5.258+-0.016,
  Ks=5.015+-0.020(2MASS), (V-J) = 9.26-5.888 = 3.372, (V-Ks)=4.245(HIP
  & 2MASS). Combining 2MASS JHKs and Casagrande08 relations, mbol =
  7.507+-0.010, hence BCv = mbol - V = 7.507 - 9.26 = -1.753, BC_Ks =
  7.507 - 5.015 = 2.492. Plx = 127.08+-1.90 mas => Mv = 9.78+-0.04,
  M_Ks = 5.54+-0.04, Mbol = 8.03+-0.03, logL = -1.315+-0.014.  Teffs:
  3407K(Leger15), 3425K(Houdebine10),
  3445K(Casagrande08,Rajpurohit13#2), 3560K(Morales08),
  3575K(Stelzer13), 3581K(Terrien15#4), 3615K(Terrien15#2),
  3616K(Terrien15#3), 3623+-60K(Mann15#1), 3651+-65K(Gaidos14),
  3686K(Terrien15#1), 3696+-36K(Mann15#2), 3700K(Rajpurohit13#1) =>
  adopt Teff=3615K. Rad=0.522+-0.019Rsun(Yee17). 

# Tertiary Standard

GJ 745B = G 184-049 = HD 349726 = LHS 3433
  K7: Cannon49,Nesterov95(HDE)
  M1: Lee47
  M1.5: Bidelman85
 *M2V: Luyten55,Luyten79,Joy74,Boeshaar85(dM2,stan.),Hawley97,Kirkpatrick(unpub.,DwarfArchives),Kirkpatrick11,Lepine13,Gaidos14
  M2.1: Mann15
  M2VI: Pasinetti-Fracassini01,Gliese91(sdM2)
  M3V: Newton14(near-IR)

  Boeshaar85 calls it M2 standard, but since it does not regularly
  appear as a standard in Kirkpatrick & Henry standard lists, I leave
  it as a tertiary standard. Partkevicius86 says its metal-poor,
  Gliese91 calls it subdwarf, although heliocentric velocity is ~40
  km/s, so not extreme. Gaidos14 reports [Fe/H]=-0.33+-0.08 and
  -0.35+-0.08, Newton14 reports [Fe/H]=-0.36 and -0.48, Mann15 reports
  [Fe/H]=-0.35+-0.08, so slightly metal poor but probably still thin
  disk. AB separation 112". Secondary is of nearly identical color and
  Vmag. V=10.76(HIP), 10.769+-0.007(Mermilliod91),
  B-V=1.570+-0.015(HIP), V-I=2.52+-0.06(HIP), J=7.278+-0.021(2MASS),
  H=6.752+-0.051(2MASS), Ks=6.517+-0.023(2MASS).  V-J=3.482(HIP &
  2MASS), (V-Ks)=4.243(HIP & 2MASS). 2MASS photometry and Casagrande08
  calibration yield mbol = 9.071+-0.032. Plx =
  114.25+-2.30(vanLeeuwen07) => Mbol = 9.36, logL = -1.85, Mv =
  11.06+-0.04, M_Ks = 6.81+-0.05. BCv = mbol - V = 9.071 - 10.76 =
  -1.689, BC_Ks = 9.071 - 6.517 = 2.554. Teffs: 3367+-79K(Newton14),
  3384K(Jenkins09), 3416+-50K(Houdebine10), 3480+-73K(Gaidos14#2),
  3484+-73(Gaidos14#1), 3494+-62K(Mann15#1), 3532+-34K(Mann15#2),
  3540K(Morales08) => median Teff = 3482K. Mass:
  0.303+-0.030Msun(Mann15), 0.37+-0.05 Msun(Gaidos14).

GJ 220 = LHS 1794 = NLTT 15743 = 2MASS J05531404+2415329 = Ross 59
  M1: Luyten79
  M1.5V: Bidelman85,Gliese91,vanAltena95,Hawley97,Reid04
 *M2V: Kirkpatrick91(sec.stan),Kirkpatrick94,Hawley02(stan),Lepine13,Gaidos14

  B-V=1.50(Reid04), V-Rc=0.98(Reid04), V-Ic=2.12(Reid04),
  V=10.84(Reid04), J=7.485+-0.021(2MASS), H=6.829+-0.017(2MASS),
  Ks=6.633+-0.021(2MASS). V-Ks=4.207(Reid04,2MASS). Teffs:
  3570K(Lepine13), 3832+-85K(Gaidos14) =>
  3791K. [Fe/H]=-0.07+-0.12(Gaidos14). plx =
  51.5+-4.6mas(vanAltena95).  Mv = 9.40, M_Ks=5.19.

GJ 91 = CD-32 828 = 2MASS J02135359-3202282
  M1: Houdebine10,
  M1.5: Gliese91,Reiners12
 *M2V: Woolley70,Gray06, Kirkpatrick10(opt,near-IR pri. stan),Gaidos14
  M2.5: Bidelman85

  V=10.318+-0.004(Koen02), B-V=1.494+-0.003(Koen02),
  U-B=1.157+-0.015(Koen02), V-Rc=0.998+-0.002(Koen02),
  V-Ic=2.165+-0.002(Koen02), J=6.961+-0.020(2MASS),
  H=6.327+-0.026(2MASS), Ks=6.093+-0.016(2MASS). V-Ks=4.225
  (Koen02,2MASS).  plx=80.04+-1.68mas(Winters15).  Mv=
  9.835+-0.046(Koen02,Winters15), M_Ks=5.610+-0.048(2MASS,Winters15).
  Teff: 3433+-50K(Houdebine12),3570K(Morales08), 3757+-88K(Gaidos14)
  => Teff = 3570K. G = 11.9238+-0.0033(GaiaDR2). G-V = 9.3983 - 10.318
  = -0.9197.  plx = 78.1936 +- 0.0372 mas(GaiaDR2).
  G=9.3983 0.0007, Bp-Rp=2.2296, Bp-G=1.1759, G-Rp=1.0537.

# Deprecated Standards

GJ 393 = LHS 2272 = Ross 446
  M1/2V: Stephenson86
  M1.5V: Rojo03
 *M2V: Vyssotsky46,Lee47,Bidelman85,Henry94(Kirkpatrick12),Henry02,Bonfils13
  M2.2V: Mann15
  M2.5V: Joy74,Jenkins09,GomesdaSilva12

  V=9.655+-0.008(Mermilliod91), B-V=1.506+-0.009(Mermilliod91),
  U-B=1.226+-0.013(Mermilliod91), J=6.176+-0.021(2MASS),
  H=5.605+-0.033(2MASS), Ks=5.311+-0.023(2MASS), V-Ks=4.344.
  plx=141.50+-2.22mas(vanLeeuwen07) => Mv = 10.409+-0.035,
  M_Ks=6.065+-0.041. [Fe/H]=-0.22(Neves13).

GJ 806 = LHS 3577 = G 209-41
  M1V: Luyten79(M1)
  M1.5V: Hawley97,Reid04
 *M2V: Kirkpatrick91(sec),Kirkpatrick94
  M3V: Adams35,Joy74,Gliese91(dM3)

  I would prefer to see more agreement if it is going to be a standard. 

GJ 22AC
  M2V: McCarthy91,Kirkpatrick91(sec.stan),Hawley97,Henry02("M2.0VJ")
 *M2V+M4V: Dieterich21

  Close binary (~0.5"), which Dieterich21 explores in detail.
  Dieterich21 resolves the spectra using HST and assigns M2V (A) and
  M4V (B) using the Bochanski07 M dwarf templates.  Dieterich21:
  Mass(A) = 0.405+-0.008 Msun, Mv(A)=10.32+-0.03, M_K=6.19+-0.02,
  Teff(A) = 3577K, logg[fit](A)=5.0, logg[calc](A)=4.9,
  [Fe/H](A)=-0.19, Rad(A)=0.376+-0.018Rsun, logL(A)=-1.68+-0.09,
  EW(Halpha)(A)=0.40; Mass(B) = 0.157+-0.003, Mv(B)=13.40+-0.10,
  M_K=8.12+-0.04, Teff(B)=3196K, logg[fit]=5.1, [Fe/H](B)]-0.10,
  Rad(B)=0.179+-0.009Rsun, logL(B) = -2.52+-0.10, logg[calc](B)=5.1,
  EW(Halpha)(B)=-2.12.

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

  Too much disagreement to be useful as a standard. 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.

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.
  (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.  Teffs: 3618K(Boyajian12), 3623K(Prugniel07),
  3646+-34K(Newton14), 3650K(Woolf05), 3664+-153K(vanBelle09),
  3680K(Prugniel07#2), 3716+-125K(Newton14#2), 3792+-92K(Gaidos14) =>
  <Teff> = 3660K. [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.

GJ 250B 
 *M2.5V: Boeshaar76,Kirkpatrick91(pri),Henry02
  M2V: KeenanMcNeil76(stan),Hawley97

  Skiff07 shows no published SpTs before Kirkpatrick91 (V=10.1), but
  it was the KeenanMcNeil76 M2V standard! It appears that Kirkpatrick
  & Henry went with the Boeshaar classification over Keenan &
  McNeil's, so it has been an M2.5V standard ever since.

# Exemplars

GJ 2066 = G 113-20 = HIP 40501 = 2MASS J08160798+0118091 = StKM 2-486
 *M2V: Stephenson86(M2:V),Hawley97(M2),Lepine13(M2),Newton14(near-IR),Gaidos14(M2),Alfonso-Floriano14

  All published subtypes are M2.  V=10.08(HIP), V=10.05(Mermilliod91),
  B-V=1.51+-0.01(HIP), B-V=1.50(Mermilliod91), U-B=1.20(Mermilliod91),
  V-I=2.15+-0.08(HIP). J=6.625+-0.026(2MASS), H=6.036+-0.031(2MASS),
  Ks=5.766+-0.024(2MASS). plx = 109.62+-1.54mas(HIP2), plx =
  112.04+-0.80mas(GaiaDR1). V-Ks = 10.05 - 5.766 = 4.284.  Mv = 10.30
  (V=10.05,plx=112.04). M_Ks = 6.013+-0.029 (Ks=5.766,plx=112.04mas).
  Teffs: 3420K(Jenkins09), 3500K(Rajpurohit18), 3500K(Stelzer13),
  3500+-60K(Mann15), 3501+-73K(Gaidos14), 3520K(Morales08),
  3520K(Lepine13), 3535+-80K(Newton15), 3537+-81K(Muirhead18),
  3589K(Passagger18), 3598+-65K(Gaidos14), 3644+-30K(Mann15#2),
  3650K(Frasca09) => <Teff> = 3520K.
  G=9.1241 0.0008, Bp-Rp=2.2976, Bp-G=1.2346, G-Rp=1.0630

GJ 3809 = Wolf 1495 = StKM 2-983 = LTT 14032 = G 64-27 = 2MASS J13490104+0247281 (J1349+0247, V=11.2)
 *M2V: Lee84(M2),Bidelman85(M2:),Stephenson86,Lepine13(M2.0),Gaidos14(M2)
  M1: Lee47

  Luyten79 NLTT catalog noted binarity 'comp. 0.6"', but just recently
  resolved as pair in Gaia DR2 (now two SIMBAD entries).  Nearly
  identical mags in GaiaDR2. G(A)=10.7706, G(B)=10.8252,
  delta(G)=0.0546.  So old photometry is unresolved:
  V=11.18(Mermilliod91), B-V = 1.55(Mermilliod91),
  U-B=1.21(Mermilliod91), J = 7.839 +- 0.075(2MASS),
  H=7.237+-0.044(2MASS), Ks= 6.935+-0.023(2MASS), V-Ks = 11.18 - 6.935
  = 4.245. Teffs: 3440K(Lepine13), 3591+-60K(Gaidos14),
  3637+-81K(Muirhead18) => <Teff> 3591K.  The E(BR/RP) values are
  2.223 and 2.289, hence the photometry is corrupted.

GJ 9440 = Gl 507.1 = Ross 1007 = LTT 13871 = StKM 2-928 = 2MASS J13194014+3320477
  M1: Lee47
  M1.5: Hawley97
  M1.8: Mann15
 *M2V: Vyssotsky43,Joy74,Bidelman85,Stephenson86,Lepine13(M2),Gaidos14(M2)

  V=10.66(Mermilliod91), B-V=1.50(Mermilliod91), U-B =
  1.22(Mermilliod91), J=7.266+-0.027(2MASS), H=6.635+-0.026(2MASS),
  Ks=6.393+-0.018(2MASS).  V-Ks = 10.66 - 6.393 = 4.267. plx =
  58.94+-0.41mas (GaiaDR1), 58.86+-1.49mas (HIP2).  Mv = 9.512
  (V=10.66,plx=58.94mas). M_Ks = 5.245+-0.023 (Ks=6.393,58.94mas).
  Teffs: 3435K(Jenkins09), 3650+-60K(Mann15), 3752+-36K(Mann15#2), 3843K(GaiaDR2).
  fbol=(0.63330+-0.00510)e-8 erg/s/cm2 => mbol=8.998+-0.009mag(IAU2015
  scale) => BCv = mbol - V = 8.998 - 10.66 =
  -1.662. [Fe/H]=0.40+-0.08(Mann15).  Mass=0.597+-0.060 Msun(Mann15),
  Rad=0.598+-0.025 Rsun(Mann15).
  G=9.7058 0.0007, Bp-Rp=2.191, Bp-G=1.1569, G-Rp=1.0344.

GJ 832 = HD 204961 = LHS 3685 = HIP 106440 = L 354-89 = Smethells 83 = 2MASS J21333397-4900323
  M1V: Evans61
  M1.5V: Reid95 
 *M2V: Upgren72,Gaidos14(M2),Houdebine16(dM2)
  M2.5V: Houdebine19(dM2.5)
  M2/3V: Houk78 
  M3V: Smethells74,Bidelman85(M3)

  Included as exemplar since it is well-studied exoplanet host star
  with stellar diameter measurement from interferometry (Rabus19).
  Not great agreement on types, but since 1990 they are ~M2+-0.5.
  V=8.66(HIP), V=8.672+-0.004(Mermilliod91),
  B-V=1.460+-0.000(Mermilliod91), U-B=1.050(Mermilliod91),
  Ks=4.501+-0.018(qual=E;2MASS), J=5.349+-0.032(2MASS).
  V-Ks=8.672-4.501=4.171. Teffs: 3416+-50K(Houdebine10),
  3419+-150K(Santos13), 3512+-23K(Rabus19), 3522+-60K(Gaidos14),
  3532+-57K(Houdebine19), 3560K(Morales08), 3575K(Stelzer13),
  3586+-193K(Muirhead18), 3590+-100K(Houdebine16),
  3664+-92K(Hojjatpanah19), 3707K(Lindgren17) => <Teff> =
  3560K. [Fe/H]=-0.06+-0.04(Lindegren17),
  [Fe/H]=-0.189+-0.080(Hojjatpanah19).  Rabus19:
  tetLD=0.814+-0.010mas, fbol=(3.359+-0.113)e-8 erg/s/cm2 (=> mbol =
  7.187+-0.037 IAU2015 scale), Rad=0.435+-0.005Rsun, Teff=3512+-23K.
  BCv = mbol - V = 7.187 - 8.672 = -1.485.  BC_Ks = mbol - Ks = 7.187
  - 4.501 = 2.682.
  G=7.7376 0.0007, Bp-Rp=2.2437, Bp-G=1.1821, G-Rp=1.0616.

GJ 176 = HD 285968 = Ross 38 = LHS 196 = HIP 21932 = LTT 11495 = 2MASS J04425581+1857285
 *M2V: Vyssotsky46,Reid95(M2),RojasAyala12(K-band),Lurie13(M2),Gaidos14(M2),Mann15(M2),Terrien15(M2)
  M2.2: Mann15
  M2.5Ve: Joy74
  M3: Bidelman85
  M5: Lee47

  Well-studied nearby star, good agreement among recent types on M2V,
  and has interferometric diameter (see Rabus19).
  V=9.945+-0.007(Mermilliod91), B-V=1.535+-0.008(Mermilliod91),
  U-B=1.176+-0.114(Mermilliod91), Ks=5.607+-0.034(2MASS).  Teffs:
  3680+-60K(Mann15), 3700+-45K(Rabus19).  Rabus19:
  tetLD=0.452+-0.020mas, fbol=(1.274+-0.099)e-8 erg/s/cm2 (=>mbol =
  8.240+-0.085 IAU2015 scale), Rad=0.460+-0.020Rsun, Teff=3700+-45K.
  BCv = mbol - V = 8.240 - 9.945 = -1.705.  BC_Ks = mbol - Ks = 8.240
  - 5.607 = 2.633.  [Fe/H]=0.14+-0.08(Mann15),
  Mass=0.492+-0.049Msun(Mann15), Rad=0.452+-0.019Rsun(Mann15).
  Mann15: fbol = (1.254+-0.017)e-11 W/m2 (=> mbol = 8.257+-0.015
  IAU2015 scale) => BCv = mbol - V = 8.257 - 9.945 = -1.688. 

# Other

MK43 lists "S 3389" as a M2V standard - indeed their only M dwarf
standard. Skiff was unable to track down which star this was. It is
clearly not "HR 3389", which is a B5III (Houk82). The same
illustration of stellar spectra in MK43 also listed "S 222" which
turned out to be "HR 222", but in this instance S =/= HR.

GJ 867A = FK Aqr = HD 214479
  M0Vep: Houk88
  M1: Bidelman85,Herbig65(M1e)
  M1.5: Reid95
 *M2V: Vyssotksy52,Joy74(M2Ve),Torres06,Gaidos14(M2),Davison14(M2.0)

  Note that the types are for unresolved light of pair (AC). GJ867A is
  a SB, and part of quadruple system, with "BD" being M3.5
  (Davison14). Multiple authors note emission, SB nature, flares. 

GJ 1 = HIP 439 = LHS 1 = HD 225213 = G 267-25 = NLTT 134 = Gaia DR3 2306965202564744064 
  M1.5V: Reid95
 *M2V: Houk82,Gaidos14
  M3V: Adams35,Walker83,Bidelman85(M3)
  M3.5Ve: Joy74
  M4V: Evans61
  M6V: Adams26

  Not good agreement on type. Classified BY Dra variable in
  GCVS. Colors suggest ~M0.5-M1.5V, but Mv and Mbol are more like
  ~M2-2.5V.  plx = 230.0970+-0.0362 mas (GaiaDR3).  B-V=1.46(Koen10),
  B-V=1.462+-0.026(HIP), V=8.56(HIP), V=8.562(Koen10),
  Rc=7.589(Koen10), J=5.328+-0.019(2MASS), H & Ks are flagged=E(poor)
  in 2MASS. V-J = 8.562 - 5.328 = 3.234 (most similar to
  M1.5V). B-V=1.46 is most similar to ~M0.5V.  Mv=10.37 (typical for
  ~M2-2.5V), adopting BCv=-1.62 for M2V => Mbol=8.75, logL=-1.605
  (most similar to ~M2.5V).