The applicable transformation equations from the instrumental to the
standard UBVRI system are given by:
U-B = 0.992(U-B) + C
B-V = 1.170(B-V) + C
V-R = 0.995(V-R) + C
V-I = 1.150(V-I) + C
V = V - 0.05(B-V) + C
where the C are the zero-points which are determined each night from standard star observations.