Program sfctshift | Correct time-shift gathers 
[SYNOPSIS]
sfctshift < tgather.rsf > cgather.rsf velocity=vel.rsf dt=0.001 pad=30
[PARAMETERS]
float   | dt | =0.001 |   | 	
int     | pad | =30 |   | 	
file    | velocity | = |   | 	auxiliary input file name
[DIRECTORY]
user/zhiguang
