Earthshine blog

Earthshine blog

"Earthshine blog"

A blog about a system to determine terrestrial albedo by earthshine observations. Feasible thanks to sheer determination.

Bulk extinction coefficients

Data reduction issuesPosted by Peter Thejll May 23, 2014 01:12PM
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

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