M7.5V

Kirkpatrick(in GrayCorbally09) list LHS 2632 as the primary M7.5V
standard. However its absolute magnitudes seem unusually bright and its colors very blue compared to locus
of where you'd expect M7.5V among M7V and M8V standards.

Henry04 standard:            LHS 132 - M7.5V (primary standard)
Kirkpatrick(GrayCorbally09): LHS 2632 - M7.5V (primary standard)

ReinersBasri09 finds that the mean kinematic age of nearby M7-M9.5 stars is 3.1 Gyr.
Kirkpatrick's DwarfArchives lists 8 M7.5V stars. 

(V-R)(M7.5V)   = 2.1:  ; Bessell91 "old disk"
(R-I)(M7.5V)   = 2.2:  ; Bessell91 "old disk"

(V-Ic)(M7.5V)  = 4.24  ; pri. stan. LHS 2632 (Winters19)
(V-I)(M7.5V)   = 4.3:  ; Bessell91 "old disk"
(V-Ic)(M7.5V)  = 4.55  ; LHS 2021
(V-Ic)(M7.5V)  = 4.57  ; trend Dieterich14 SpT vs. V-Ic
(V-Ic)(M7.5V)  = 4.71  ; sec. stan. LHS 132
=> adopt (V-Ic)(M7.5V) = 4.57 [updated 7/4/2020]

(B-V)(M7.5V)   = 2.14 ; linear fit to Leggett92 (B-V=0.8367+0.2852*V-I, V-I=4.57)
=> adopt (B-V)(M7.5V) = 2.14 [updated 7/5/2020]

(G-J)(M7.5V)   = 3.607 ; Bentley18/interp
(G-Ks)(M7.5V)  = 4.543 ; Bentley18/interp
(Ks-W2)(M7.5V) = 0.449 ; Bentley18/interp
(W1-W2)(M7.5V) = 0.235 ; Bentley18/interp

(Ks-W1)(M7.5V) = 0.215 ; Bentley18/interp
(Ks-W1)(M7.5V) = 0.251 ; fit to Winters15 data for V-Ks=8.400
(Ks-W1)(M7.5V) = 0.259 ; Dupuy12 median (N=9, d<50pc)
(Ks-W1)(M7.5V) = 0.268 ; Dupuy12 trend 
(Ks-W1)(M7.5V) = 0.273 ; Avenhaus12 for V-Ks=8.40
=> adopt (Ks-W1)(M7.5V) = 0.26 [updated 12/28/2019]

(V-K)(M7.5V)   =    9.0: ; Bessell91 "old disk"
(V-Ks)(M7.5V)  = 8.495 ; exemplar 2MASS J15242475+2925318
(V-Ks)(M7.5V)  = 8.461 ; sec. stan. LHS 132
(V-Ks)(M7.5V)  =   8.45  ; non-standard LHS 2021
(V-Ks)(M7.5V)  =   8.438 ; non-standard LHS 1367
(V-Ks)(M7.5V)  = 8.33 ; interp M6.5V(V-Ks=7.60)-M8V(V-Ks=8.70)
(V-Ks)(M7.5V)  = 8.35 ; halfway M7V(8.00),M8V(8.70)
(V-Ks)(M7.5V)  =  8.18  ; smoothed fit to Dieterich SpT vs V-Ks
(V-Ks)(M7.5V)  =  8.14  ; trend fit to Dahn17 for M7.5V
(V-Ks)(M7.5V)  = 7.701 ; pri. stan. LHS 2632 [note how blue! appears atypical]
(V-Ks)(M7.5V)  =   7.46  ; non-standard LHS 2645 
=> adopt (V-Ks)(M7.5V) = 8.35 [updated 12/26/2020]
=> adopt (G-Ks)(M7.5V) = 5.28 [updated 12/27/2021; V-Ks=8.35, G-V=-3.07]

=> adopt (V-J)(M7.5V)  = 7.378
=> adopt (V-H)(M7.5V)  = 8.028

(G-Ks)(M7.5V) = 5.016 ; pri. stan. LHS 2632 = LP 321-222
(G-Ks)(M7.5V) =  5.15  ; exemplar 2MASS J15242475+2925318 = LSPM J1524+2925
(G-Ks)(M7.5V) =  5.223 ; exemplar 2MASS J22215313+1158222
(G-Ks)(M7.5V) = 5.28  ; V-Ks=8.35, G-V=-3.07 (M_G=15.09, Mv=18.16)
(G-Ks)(M7.5V) = 5.299 ; sec. stan. LHS 132 = LP 938-71
=> adopt (G-Ks)(M7.5V) = 5.17 [updated 12/26/2020]

(G-V)(M7.5V) = -3.1617 ; LHS_132
(G-V)(M7.5V) = -3.15   ; M_G - Mv (median values seem well-defined
(G-V)(M7.5V) = -3.09   ; trinomial trend through late Ms
(G-V)(M7.5V) = -3.07   ; M_G=15.09, Mv=18.16
(G-V)(M7.5V) = -2.67   ; pri. stan. LHS 2632 = LP 321-222 
=> adopt (G-V)(M7.5V) = -3.07 [updated 12/26/2020]


(r-i)(M7.5V) = 1.927 (+-0.05 rms) ; West05 fit for (V-Ic)=4.57

(i-z)(M7.5V) = 1.599 ; poly fit to d<75pc M dwarfs in SIMBAD for G-Ks=5.28
=> adopt (i-z)(M7.5V) = 1.60 [updated 12/27/2021]

(z-J)(M7.5V) = 2.002 (+-0.053 rms) ; poly fit to SIMBAD d<50pc M dwarfs for G-Ks=5.17
=> adopt (z-J)(M7.5V) = 2.00 [updated 12/27/2021]

(Ks-L')(M7.5V) = 0.335 ; Dupuy12 polynomial

(J-Ks)(M7.5V)  = 1.061+-0.032 ; sec. stan. LHS 132
(J-Ks)(M7.5V)  = 1.060(+-0.021 sem,+-0.051 stdev) ; N=9 Cruz03 M7.5V
(J-Ks)(M7.5V)  = 1.018+-0.029 ; pri. stan. LHS 2632
=> adopt (J-Ks)(M7.5V) = 1.04

(J-H)(M7.5V)   = 0.644(+-0.012 sem,+-0.027 stdev) ; N=9 Cruz03 M7.5V 
(J-H)(M7.5V)   = 0.644+-0.031 ; pri. stan. LHS 2632
(J-H)(M7.5V)   = 0.650        ; trend for V-Ks=8.35
(J-H)(M7.5V)   = 0.651+-0.034 ; sec. stan. LHS 132
=> adopt (J-H)(M7.5V)  = 0.650 [updated 1/15/2021]

(H-Ks)(M7.5V)  = 0.423 ; trend of Dieterich14 for V-Ks=8.4
(H-Ks)(M7.5V)  = 0.410+-0.032 ; sec. stan. LHS 132
(H-Ks)(M7.5V)  = 0.407(+-0.014 sem,+-0.047 stdev) ; N=9 Cruz03 M7.5V 
(H-Ks)(M7.5V)  = 0.374+-0.029 ; pri. stan. LHS 2632
=> (H-Ks)(M7.5V) = 0.42 [last updated 5/5/2017]

(Bp-Rp)(M7.5V) =  4.3737 ; LHS_2632 pri. stan.
(Bp-Rp)(M7.5V) =  4.6580 ; 2MASS J22215313+1158222 exemplar 
(Bp-Rp)(M7.5V) =  4.6617 ; 2MASS J15242475+2925318 exemplar
(Bp-Rp)(M7.5V) = 4.719  ; M5-M8.5 color trend 
(Bp-Rp)(M7.5V) =  4.9580 ; LHS_132 sec. stan.
=> adopt (Bp-Rp)(M7.5V) = 4.72 [updated 11/18/2020]

(G-Rp)(M7.5V) = 1.4986 ; LHS_2632 pri. stan.
(G-Rp)(M7V)   =  1.52     ; M7V mean
(G-Rp)(M7.5V) = 1.5274 ; 2MASS J15242475+2925318 exemplar
(G-Rp)(M7.5V) = 1.5549 ; 2MASS J22215313+1158222 exemplar
(G-Rp)(M7.5V) = 1.555  ; M0V-M9V color trend 
(G-Rp)(M7.5V) = 1.5673 ; LHS_132 sec. stan. 
(G-Rp)(M8V)   =  1.57     ; M8V mean
=> adopt (G-Rp)(M7.5V) = 1.55 [updated 12/10/2020]

(Bp-G)(M7.5V) = 2.8751 ; LHS_2632
(Bp-G)(M7.5V) = 3.1031 ; 2MASS J22215313+1158222 exemplar 
(Bp-G)(M7.5V) = 3.17   ; Bp-Rp=4.72, G-Rp=1.55
(Bp-G)(M7.5V) = 3.3907 ; LHS_132
=> adopt (Bp-G)(M7.5V) = 3.17 [updated 11/18/2020; Bp-Rp=4.72, G-Rp=1.55]


Teff(M7.5V) = 2748 K ; Dupuy17(SaumonMarley08 scale)
Teff(M7.5V) = 2723 K ; Dupuy17(Lyon model scale)
Teff(M7.5V) = 2620 K ; empirical L-R relation, for logL=-3.236
Teff(M7.5V) = 2630 K ; Mann15 [Fe/H]=0.0 radius for M_K=9.8
Teff(M7.5V) = 2611 K ; Filippazzo15 calibration (M6V-T9V)
Teff(M7.5V) = 2600 K ; non-stan. LHS 1367
Teff(M7.5V) = 2600 K ; Rajpurohit13(N=5)
Teff(M7.5V) = 2600 K ; Cifuentes20 <Teff> for CARMENES M7.5V(N=5)
Teff(M7.5V) = 2600 K ; pri. stan. LHS 2632 (Rajpurohit13)
Teff(M7.5V) = 2598 K ; non-stan. LP 851-346 (Dieterich14)
Teff(M7.5V) =   2548 K ; Golimowski04
Teff(M7.5V) = 2513 K ; sec. stan. LHS 132 (Dieterich14)
Teff(M7.5V) =   2450 K ; Bessell91 "old disk"
=> adopt Teff(M7.5V) = 2630 K (logT = 3.420) [updated 4/9/2020]

BCv(M7.5V) = -5.8  ; Bessell91("old disk"; BCv = (V-I)-BC_I)
BCv(M7.5V) = -5.32 ; BC_K=3.03, V-Ks=8.35
=> adopt BCv(M7.5V) = -5.32 [adopted 1/15/2021] 

BC_K(M7.5V) =  3.092 ; non-standard 2MASS J22215313+1158222 (see below)
BC_K(M7.5V) =  3.074 ; Golimowski04
BC_K(M7.5V) = 3.03  ; trend for mid/late-M dwarfs
BC_K(M7.5V) =  2.991 ; non-standard LHS 2645 (see below)
BC_K(M7.5V) =  2.989 ; pri. stan. LHS 2632 (see below)
BC_K(M7.5V) =  2.931 ; sec. stan. LHS 132 (see below)
BC_K(M7.5V) =  2.923 ; non-standard 2MASS J15242475+2925318 (see below)
=> adopt BC_K(M7.5V) = 3.03 [updated 11/3/2019]

Mv(M7.5V)   = 18.25 ; Dieterich14 calibration for V-Ks=8.35
Mv(M7.5V)   =   18.23 ; non-stan. LHS 2021
Mv(M7.5V)   =   18.21 ; non-stan. LHS 1367
Mv(M7.5V)   = 18.16 ; halfway M7V(Mv=17.70)-M8V(Mv=18.62)
Mv(M7.5V)   = 18.10 ; sec. stan. LHS 132 
Mv(M7.5V)   =   17.17 ; non-stan. LHS 2645
Mv(M7.5V)   = 16.99 ; pri. stan. LHS 2632 = LP 321-222 
=> adopt Mv(M7.5V)   = 18.16 [updated 12/28/2020] (V-Ks=8.35, M_Ks=9.81)
=> adopt M_Ks(M7.5V) =  9.81 [updated 12/26/2020] (V-Ks=8.35, Mv=18.16)
=> adopt M_G(M7.5V)  = 15.09 [updated 12/28/2020] (Mv=18.16, G-V=-3.07)

M_G(M7.5V) =   14.64 ; LP 229-30 
M_G(M7.5V) =   14.72 ; LSR J1524+2925
M_G(M7.5V) =   14.93 ; LP 851-346
M_G(M7.5V) =   14.96 ; SCR J1546-5534
M_G(M7.5V) =   14.98 ; LP 655-48
M_G(M7.5V) =  15.05 ; nearest 10 M7.5Vs in SIMBAD median
M_G(M7.5V) = 15.085 ; halfway between M7V(M_G=14.72) and M8V(15.45)
M_G(M7.5V) =   15.12 ; LP 485-17
M_G(M7.5V) =   15.17 ; TRAPPIST-1
M_G(M7.5V) =   15.17 ; LP 888-18
M_G(M7.5V) =  15.22 ; trend SIMBAD d<10pc sample
M_G(M7.5V) =   15.34 ; LP 135-272
M_G(M7.5V) =   15.91 ; LP 388-55

M_Ks(M7.5V) =   9.94  ; Dieterich14 calibration for V-Ks=8.4
M_Ks(M7.5V) =   9.93  ; EEM fit to Dieterich+14 for V-Ks=8.4
M_Ks(M7.5V) =  9.83  ; exemplar 2MASS J22215313+1158222
M_Ks(M7.5V) = 9.81  ; halfway M7V(M_Ks=9.70)-M8V(M_Ks=9.92)
M_Ks(M7.5V) =   9.78  ; non-stan. LHS 2021
M_Ks(M7.5V) =   9.78  ; non-stan. LHS 1367 
M_Ks(M7.5V) =   9.75  ; EEM fit to Reid CNS3 data
M_Ks(M7.5V) =  9.73  ; mean for standards+exemplars
M_Ks(M7.5V) =   9.68 ; Dupuy12 polynomial
M_Ks(M7.5V) =  9.64  ; sec. stan. LHS 132
M_Ks(M7.5V) =  9.62  ; exemplar 2MASS J15242475+2925318
M_Ks(M7.5V) =   9.61 ; Dupuy12 mean
M_Ks(M7.5V) =  9.54  ; non-stan. LHS 2645
M_Ks(M7.5V) = 9.29   ; pri. stan. LHS 2632 = LP 321-222 

logL(M7.5V) = -3.240 dex ; M_Ks=9.81, BC_Ks=3.03, Mbol=12.84
=> adopt logL(M7.5V) = -3.240 [adopted 12/28/2020]
=> adopt Mbol(M7.5V) = 12.840 [adopted 12/28/2020]

Rad(M7.5V) =  0.1156 Rsun ; Mann15 trend M_Ks=9.80, [Fe/H]=0.0
Rad(M7.5V) = 0.1155 Rsun ; logL=-3.240, Teff=2630K
Rad(M7.5V) =  0.1175 Rsun ; Rabus19 trend for Teff=2620K [cool edge of relation 2600K]
Rad(M7.5V) =  0.125 Rsun ; LP851-346 Dieterich14
=> adopt Rad(M7.5V) = 0.116 Rsun [adopted 12/28/2020]

Mass(M7.5V) = 0.0876 Msun ; Mann18 calib. for M_Ks=9.81
Mass(M7.5V) = 0.088  Msun ; Benedict16 calibration for M_Ks=9.78
=> adopt Mass(M7.5V) = 0.088 Msun [updated 11/15/2021]

# No Standards

Boeshaar85, Kirkpatrick91, Kirkpatrick97, Henry02 do not list an M7.5V standard

# Primary Standard
 
LHS 2632 = LP 321-222 = 2MASS J12465176+3148104 = NLTT 31871
  M5.0V: ReidGizis05
  M6.5V: Gizis00
  M7: Kirkpatrick93,Jenkins09(M7.0)
 *M7.5V: Kirkpatrick92,Kirkpatrick95,[Basri06,Schmidt07,Cruz07,Faherty09,Reiners09],Kirkpatrick(GrayCorbally09)(pri)

  Note that the ones in brackets: it isn't clear whether any of these
  were new/checked classifications, they may have just been citing
  Kirkpatrick95.  Kirkpatrick(www.dwarfarchive.org) cites
  Kirkpatrick(1992;PhD Thesis) as the source for this classification,
  but it disagrees with his 1993 published classification. It is
  surprising that the Kirkpatrick and ReidGizis types disagree by a
  2.5 subtypes?  Skiff MK catalog only lists the ReidGizis05 type as
  of 3/2016. I would like to see better agreement among the types, but
  Kirkpatrick did claim this is a primary standard in GrayCorbally09,
  so I retain it as a primary standard for now. Proper motion is
  ~0.8"/yr (Lepine05). Is 23" away from a 14th mag star. I can find no
  reliable UBVRI photometry for this star. V=18.89(Lepine05, no
  uncertainty), V=18.91(Winters19), V=19.15(Smart10),
  R=16.80(Smart10,transformed from GSC2.3, so probably poor),
  I=14.76(Smart10), J=12.227+-0.022(2MASS), H=11.583+-0.022(2MASS),
  Ks=11.209+-0.019(2MASS), J-Ks=1.018+-0.029, J-H=0.644+-0.031,
  H-Ks=0.374+-0.029. mbol =
  14.198(Pecaut13,JHKs relation) => BC_Ks=2.989.  plx = 53.3+-2.3 mas
  (Smart10) => Dist = 18.76+-0.81 pc. GaiaEDR3: plx=41.3832+-0.1021mas,
  G=16.236963 0.003006, E(BP/RP)=1.727, Bp-Rp=4.386515, Bp-G=2.886478,
  G-Rp=1.500036.  (G-Ks)=5.016, M_G=14.309, M_Ks=9.293.  G-V = 16.237
  - 18.91 = -2.673. V-Ks = 18.91 - 11.209 = 7.701. Mv=16.99. 

# Secondary Standard

LHS 132 = LP 938-71 = NLTT 938-71 = 2MASS J01025100-3737438
 *M7.5V: Henry04(pri. stan.)
  M8: Reid08, Reyle06(M8.0e), Schmidt07, Rajpurohit13, Dieterich14(Reyle06)

  The star has no reliable published UB photometry. I'm only leaving
  it in as a secondary standard rather than deprecated since there are
  no other M7.5V standards available, and Henry04 claimed it was a
  M7.5V primary standard (but multiple subsequent papers have called
  it M8). However its V-Ks color and Mv/M_Ks absolute magnitudes are
  typical for M7.5V among other stars of the same classification.
  V=18.53+-0.021(Dieterich14), Rc=16.30+-0.008(Dieterich14),
  R=17.14(Rajpurohit13), Ic=13.82("converted";Dieterich14),
  V-Ic=4.71(Dieterich14), I=13.83(Rajpurohit13).  J =
  11.130+-0.023(2MASS), H = 10.479+-0.024(2MASS), Ks=
  10.069+-0.021(2MASS), J-Ks=1.061+-0.032(2MASS),
  J-H=0.651+-0.034(2MASS), H-Ks=0.410+-0.032(2MASS), W1 =
  9.844+-0.024(WISE), W2 = 9.607+-0.021(WISE),
  W3=9.294+-0.029(WISE). V-Ks = 8.461(Dieterich14,2MASS).
  mbol=13.00+-0.03 (JHK=>Pecaut13) => BC_Ks=2.931. Faherty09 lists d =
  12.20+-0.40 pc, cites Costa05. Vtan = 85.6+-2.9 km/s, so this is
  almost certainly a very old star.  Teff=2513+-29K(Dieterich14),
  2600K(Rajpurohit13). logL=-3.194+-0.030(Dieterich14),
  Rad=0.133+-0.0056(Dieterich14),Proper motion
  1.5"/yr. Plx=81.95+-2.73(Costa05). Mv=18.10+-0.08
  (V=18.53+-0.021,plx=81.95+-2.73mas),
  M_Ks=9.64+-0.08(Ks=10.069+-0.021,plx=81.95+-2.73mas).
  (G-Ks)=5.299, M_G=15.087, M_Ks=9.788. 

# Exemplars

2MASS J15242475+2925318 = LSPM J1524+2925 = WISEP J152424.72+292525.2
 *M7.5V: Reid02(Kirkpatrick97?),Gizis00(Crossfield14 references Gizis00?),Kirkpatrick11,Kirkpatrick(DwarfArchive,unpublished). 

  Reid02 lists M7.5 and cites Kirkpatrick97, but the star does not
  appear in that paper.  Crossfield14 references Gizis+2000, but the
  star does not appear in either of the Gizis+2000 papers. SIMBAD
  shows no references to the star before Reid02.  V=17.97(NOMAD),
  V=18.23+-0.29(GSC2.3), V=18.65(Lepine05), J=11.206+-0.022(2MASS),
  H=10.535+-0.021(2MASS), Ks=10.155+-0.015(2MASS),
  V-Ks=18.65-10.155=8.495(Lepine05,2MASS), mbol =
  13.078+-0.026(JHK=>Pecaut13), BC_Ks = 13.078-10.155 = 2.923.  plx =
  78.3+-4.4mas (Dittman14), Mv=18.12(Lepine05,Dittman14),
  M_Ks=9.62+-0.12 (2MASS,Dittman14).  GaiaDR2: plx =
  76.4976+-0.0857mas, G=15.3051+-0.0006, E(BR/RP)=1.780, Bp-Rp=4.6617,
  Bp-G=3.1343, G-Rp=1.5274. (G-Ks)=5.15, M_G=14.723, M_Ks=9.573. 
  
2MASS J22215313+1158222
  M7e: West08
 *M7.5: Allen07,Kirkpatrick10
  M8e: West11

  V=17.97(NOMAD), J=13.402+-0.025(2MASS), H=12.755+-0.026(2MASS),
  Ks=12.361+-0.028(2MASS), V-Ks=5.609 (not clear if NOMAD Vmag is OK,
  prob. not), mbol = 15.453+-0.010(JHK=>Pecaut13), BC_Ks = 15.453 -
  12.361 = 3.092. Poor V photometry.  GaiaDR2: plx=31.1794+-0.2498mas,
  G=17.5837+-0.0022, E(BR/RP)=1.826, Bp-Rp=4.6580, Bp-G=3.1031,
  G-Rp=1.5549 => M_G=15.05, Mv=15.44:, M_Ks=9.83. (G-Ks)=5.223. 

# Other Stars

LHS 2645 = 2MASS J12531240+4034038 = LP 218-8
  M7: Kirkpatrick93,Reid05(M7Ve),West08(M7e),Hilton10,West11(M7e)
 *M7.5V: Kirkpatrick92(DwarfArchive),Kirkpatrick95,Schmidt07,Faherty09,Reiners09,McLean12,Kirkpatrick10,Desphande13

  One of two M7.5Vs in Kirkpatrick95(other being LHS 2632). 
  Teff: 2487K(Jenkins09). V=18.43(Salim03), V=18.80(Jenkins09),
  V=18.90(Lepine05), J=12.185+-0.019(2MASS), H=11.545+-0.022(2MASS),
  Ks=11.162+-0.019(2MASS), V-Ks=7.64(Jenkins09,2MASS),
  mbol=14.153+-0.005(JHK=>Pecaut13) => BC_Ks = 14.153 - 11.162 =
  2.991. plx = 47.3+-11.7mas(Finch16,URAT) => 21.1+-5.6
  pc. Dist=17.5+-1.7pc(Deshpande13,spectrophotometric).
  Mv=17.17(V=18.80,plx=47.3mas),
  M_Ks=9.54+-0.54(Ks=11.162+-0.019,plx=47.3+-11.7mas).

LHS 2021 = SDSS J083032.37+094712.7 = 2MASS J08303256+0947153 = L 485-17
  M6.5: Costa06(Dupuy12)
 *M7.5Ve: Henry04,Faherty09(M7.5)
  M8: Schmidt07,Reid08,Carson11,Kirkpatrick(DwarfArchives,unpublished)
  M9e: West11

  plx=63.67+-1.15mas(Riedel10). V-Ks=8.45(Hosey15). V=19.21(Hosey15),
  R=16.94(Hosey15), I=14.66(Hosey15), J=11.890+-0.022(2MASS),
  H=11.165+-0.021(2MASS), Ks=10.756+-0.023(2MASS). Mv=18.23
  (V=19.21,plx=63.67mas), M_Ks=9.78+-0.05(Ks=10.756+-0.023,
  plx=63.67+-1.15mas).

LHS 1367 = 2MASS J02150802-3040011 = L 885-35
 *M7.5V: Kirkpatrick(DwarfArchive,unpublished)
  M8e: Reyle06,Faherty09(M8),Antonova13(M8),Rajpurohit13

  Teff=2600K(Rajpurohit13). V=18.98(Winters15), R=16.70(Winters15),
  I=14.23(Winters15), J=11.617+-0.026(2MASS), H=10.953+-0.024(2MASS),
  Ks=10.542+-0.023(2MASS),
  V-Ks=8.438. plx=70.26+-1.23mas(Weinberger16).
  Mv=18.21(V=18.98,plx=70.26mas),
  M_Ks=9.78+-0.04(Ks=10.542,plx=70.26).  
  
LP 789-23 = 2MASS J10063197-1653266
 *M7.5V: Cruz03(Liebert06,+-0.5 subtype), Reid03(M7.5Ve),Cruz07,Schmidt07
  M7.0: Crifo05,Rajpurot13(M7)

  Rc=16.875+-0.005, Ic=14.573+-0.003, (R-I)c=2.302(Liebert06).  Teff =
  2700K(Rajpurohit13).

LP 655-48 = 2MASS J04402325-0530082 = DENIS-P J0440231-053009
   M6.0: Cruz02,Gagne14,Alonso-Floriano15
   M6.5Ve: Reidel14
  *M7V: Cruz03,Henry04(M7Ve),Schmidt07,Cruz07,Despande12,Crossfield14
   M7.5Ve: McCaughrean02,Lodieu05,Crifo05,Phan-Bao17

   Not great agreement on subtype, but median subtype is ~M7.0V.
   V=17.86(Casagrande08), V-Rc=1.910(Casagrande08),
   V-Ic=4.230(Casagrande08). plx=102.30+-1.02mas(Weinberger16).
   V-Ks=8.24(Hosey15). Teffs: 2250+-118K(Casagrande08),
   2600K(Rajpurohit13). mbol = 12.845(Casagrande08)

TRAPPIST-1 = 2MASS J23062928-0502285
 *M7.5e: Gizis00,Reid07(M7.5)
  M7.5(opt),M8(near-IR),M7.5(adopted): Best18
  M8.0: Reiners09
  M8: Burgasser15

  BurgasserMamajek17 shows V-Ks color is more like M7.5V, but
  near-IR spectra are more like M8. (V-Ks)=8.45, Mv=18.27, M_Ks=9.81. 


# V-Ks vs. Mv
V-Ks  Mv     M_Ks      SpT(M) 
8.495 18.12  9.62+-0.12 7.5 2MASS_J15242475+2925318 (Exemplar)
8.461 18.10  9.64+-0.08 7.5 LHS 132 (sec. stan.)
8.45  18.23  9.78+-0.05 7.5 LHS 2021
8.438 18.21  9.78+-0.04 7.5 LHS 1367
7.94  17.78  9.84+-0.10 7.5 LHS 2632 (pri. stan.)
7.64  17.17  9.54       7.5 LHS 2645