David Benn - 2014-04-27

From Josch in email on Apr 20:

Here is the comment of Pierre how things are calculated based on instrumental mags.

As we are using differential photometry, the magnitudes of Variable and Check stars are calculated from instrumental magnitudes:

Vm = (v-r) + R
CKm = (ck-r) + R
and Rm = (r-r) +R ( trivial )
where
v, r ck are instrumental magnitudes
R is the catalog magnitude of reference star
Vm CKm and Rm are the measured (adjusted) magnitude.

So with this VSTAR should be able to plot the comp stars in real magnitudes based on the AAVSO file’s instrumental magnitudes.