To check which coefficients were applied to the frame zeropoints, the
date of processing is relevant, NOT the observing date! As a rule of
thumb, data are processed on average 10 days after they were observed.

            extinction              colour            colour
            coefficient             term
until 
2006-07-18

U_BESS       0.41                   +0.10              U-B
B_BESS       0.21                   -0.09              B-V
V_BESS       0.16                   +0.05              B-V
R_BESS       0.13                   +0.02              V-R
I_BESS       0.09                   -0.08              V-R
 
2006-07-25
to
2006-08-01

U_BESS       0.448                  +0.071             U-B
B_BESS       0.248                  -0.078             B-V
V_BESS       0.136                  +0.033             B-V
R_BESS       0.086                  +0.034             V-R
I_BESS       0.063                  -0.037             V-R

2006-08-02 
to 
2007-03-25

U_BESS       0.425                  +0.067             U-B
B_BESS       0.245                  -0.078             B-V
V_BESS       0.125                  +0.035             B-V
R_BESS       0.081                  +0.042             V-R
I_BESS       0.038                  -0.038             V-R

In between the FORS1 detectors changed. All data observed until
2007-03-25 were reduced with the coefficients given above.

since 
2007-03-31

U_BESS       0.456                  +0.091             U-B
B_BESS       0.255                  -0.107             B-V
V_BESS       0.132                  +0.020             B-V
R_BESS       0.090                  +0.000             V-R
I_BESS       0.051                  -0.060             V-R
u_HIGH       0.440                  +0.106             U-B
b_HIGH       0.230                  +0.069             B-V
v_HIGH       0.115                  +0.049             B-V
g_HIGH       0.182                  +0.031             B-V

Last update: 2007-04-25