Color indexes calculation

[Degen1103]

Would you please recommend correct method of LPV color indexes calculation from scattered data? For example, light curves and phase plots of well known RVa EP Lyr have clear shape differences and shifts of extremums. How to calculate (B-V)=f(phase) or “delay” phase(V)-phase(B-V)?

I used absolutely awful polynomial interpolation and suspect it is wrong way.

Regretfully, I did not find suitable functions in Peranso. May VStar help? Or maybe there is ready application for such kind of analysis?

Hope for your kind explanations!

Mikhail

[Degen1103]

I tried to find indexes with absolutely stupid manual method finally, but it
is obviously wrong way. I’m confident there is normal solution of the “problem”.
(I use LibreOffice freeware, which returns polynomial coeff-ts in short format, so calculation of averaged BgVI values is impossble!)

[Degen1103]

Hmmm I found in VStar B-V plugin and tested it on EP Lyr AAVSO BV data.
I did not fully unterstand algorytm, but plugin works and gives B-V phase plot with smoothed polynomial approximation.