In this entry we estimated extinction coefficients for all data from each filter – that is, we did not study each night individually, but took all B, V etc data seperately.
We found, at that time:
B 0.15 mag/airmass
V 0.10 mag/airmass
VE1 0.08 mag/airmass
VE2 0.06 mag/airmass
IRCUT 0.12 mag/airmass
Since then we have eliminated some observations that we now know had problems of one sort or the other, and have the opportunity to re-estimate extinction coefficients. We now find:
B 0.18 mag/airmass
V 0.11 mag/airmass
VE1 0.06 mag/airmass
VE2 0.09 mag/airmass
IRCUT 0.05 mag/airmass
kB is 0.03 higher; kV 0.01; kVE1 0.02 lower; kVE2 is 0.03 higher and kIRCUT is 0.07 lower. The changes of +/- 0.02 are as expected given Chris’ analysis of extinction from single nights, but the change in kIRCUT is large – however, it is now more in line with kVE1: the two filters are almost identical, so that is a step in the right direction.
We found these extinction coefficients by plotting extinction-corrected flux against lunar phase and fitting a third-order polynomial. For trial values of the extinction coefficient
