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Polarimetry

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

Comments

Jeremy's picture

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

All the best,

Jeremy

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].

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