T0.5V

Teff(T0.5V) = 1231 K ; Filippazzo15 calibration (M6V-T9V)
Teff(T0.5V) = 1246 K ; Kirkpatrick20 (Table 13 polynomial)

M_J(T0V) = 14.734 ; EEM fit to L/T dwarfs d<25pc

M_Ks(T0.5V) =  12.45 ; WISE_1809-0448 calc using Kirkpatrick20 (plx=49.2mas)
M_Ks(T0.5V) = 13.21  ; fit to Kirkpatrick20 L7-T3 dwarfs
M_Ks(T0.5V) = 13.21  ; Luhman16B 
M_Ks(T0.5V) = 13.21  ; trend to L/T dwarfs in notes (1/2021)
=> adopt M_Ks(T0.5V) = 13.21 [updated 12/30/2020]

# Examples

Luhman 16B = WISE J104915.57−531906.1B
   T0: Lodieu15(T0+-1) 
  *T0.5: Burgasser13(T0.5+-1; Burgasser14,Faherty14 cites as T0.5+-0.5)

   T dwarf companion to famous L/T binary at 2pc discovered by
   Luhman13(2013ApJ...767L...1L), and a flux-reversal binary which
   switches which component is brighter between J and K band.
   Faherty14 estimates B to be only ~30K cooler (1310+-30K for A,
   1280+-75K for B). logL = -4.68+-0.13(Lodieu15).
   J=11.40+-0.05(Burgasser14,2MASS sys.),
   H=10.34+-0.05(Burgasser14,2MASS sys.),
   Ks=9.71+-0.10(Burgasser14,2MASS sys.).
   plx=500.51+-0.11mas(Sahlmann15) => M_J=14.897+-0.050.
   M_Ks=13.207+-0.100. Teff(B): 1261+-55K(Kirkpatrick20),
   1280+-75K(Faherty14), 1320+185-135K(Lodieu15) => <Teff> = 1280K.