British Astronomical Association
Supporting amateur astronomers since 1890

Secondary menu

Main menu

BAA Community Member Pages john simpson
Image search



Expand image

About this observation
john simpson
Time of observation
20/01/2018 - 21:00
Polarisation Standard Stars
Observing location
SW Scotland
Celestron C6
Wollaston Prism
Cousins V-Band filter
ATIK 314L+
Various depending on target
Like This Image

Polarisation measurement - an itch I have wanted to scratch for some while. Graph shows calibrations in V-Band against various 'zero' and 'high' polarisation standard stars [plus a few others]. Four images taken of each target at 0, 45, 90, 135 deg. rotation angles. The Wollaston separates the target into 'ordinary' & 'extraordinary' images and these are processed to derive Stokes Q & U and thence polarisation magnitude and angle. My hope eventually with bigger telescope & light grasp is to couple to my ALPY.


Jeremy's picture

This is really interesting work, John. I look forward to seeing how you progress.

All the best,


John Simpson's picture

Hello Jeremy, thanks, first steps along what I hope will be a long path.

Grant Privett's picture

Really nice work. 

Is the top chart the degree of linear polarisation?

Also, what filters did you use?

John Simpson's picture

Hello Grant, thanks & yes, I should have made it clear that the measurements are all of the degree of linear polarisation for each target measured using my setup compared to its published value as a standard reference.

I used an Astrodon Johnson/Cousins Photometric V-Band filter [I have B and Rc, but no measurements with these as yet].

Copyright of all images and other observations submitted to the BAA remains with the owner of the work. Reproduction of the work by third-parties is expressly forbidden without the consent of the copyright holder. For more information, please contact the webmaster.