This plot shows the measured angle of highest polarimetry (P_THETA) of the high polarimetric standard star minus the 
tabulated angle: qc_THETA_offset. Only V-band values are tabulated for the high polarized standard stars.
Trending plots for the R and I band assume that the real (but not tabulated) R and I band polarimetric values are those of the V band.
Not all polarimetric standard stars of the catalogue have an entry for the angle.
All values are given in degrees.
</font><p><font size="2">
For the non-polarized standard stars, the angle is not defined.