!# $U$ filter from Koo (1986), ApJ 311, 651.
"UK"
"energy"       
"Vega"    0.
 3100.   0.000
 3150.   0.087
 3200.   0.130
 3250.   0.234
 3300.   0.339
 3350.   0.431
 3400.   0.524
 3450.   0.606
 3500.   0.688
 3550.   0.782
 3600.   0.876
 3650.   0.938
 3700.   1.000
 3750.   0.987
 3800.   0.973
 3850.   0.838
 3900.   0.703
 3950.   0.488
 4000.   0.274
 4050.   0.186
 4100.   0.099
 4150.   0.049
 4200.   0.000
