Position Angle Correction, CPA
The waveplate is not achromatic, hence the polarization
position angle correction (CPA) is wavelength dependent.
From broad band imaging polarimetry the CPA is
determined as:
PA U |
PA B |
PA V |
PA R |
PA I |
Date |
Star |
-3.8 |
-6.1 |
-2.8 |
+0.3 |
+1.9 |
11/12-2010 |
BD+59 389 |
The numbers are average from three nights (except U-band one night)
and typical position angle accuracy is better than 0.4 degrees
(except U-band about 0.8 degrees).
|