!# $v$ filter from Thuan & Gunn (1976), PASP 88, 543.
"v"
"energy"       
"TG"
 3600.   0.000
 3650.   0.316
 3700.   0.553
 3750.   0.697
 3800.   0.842
 3850.   0.921
 3900.   1.000
 3950.   0.980
 4000.   0.961
 4050.   0.836
 4100.   0.711
 4150.   0.553
 4200.   0.395
 4250.   0.283
 4300.   0.171
 4350.   0.118
 4400.   0.066
 4450.   0.053
 4500.   0.039
 4550.   0.033
 4600.   0.026
 4650.   0.020
 4700.   0.013
 4750.   0.007
 4800.   0.000
