!# $K$ filter from Bessel & Brett (1988), PASP 100, 1134.
"K"
"energy"       
"Vega"    0.
19600.   0.000
19800.   0.204
20000.   0.306
20200.   0.561
20400.   0.755
20600.   0.561
20800.   0.786
21000.   0.867
21200.   0.918
21400.   0.959
21600.   0.959
21800.   0.969
22000.   0.959
22200.   0.980
22400.   1.000
22600.   0.990
22800.   0.980
23000.   0.929
23200.   0.898
23400.   0.857
23600.   0.811
23800.   0.765
24000.   0.653
24200.   0.378
24400.   0.102
24600.   0.051
24800.   0.000
