Observation by john simpson: Polarimetry

Uploaded by

john simpson

Observer

john simpson

Observed

2018 Jan 20 - 21:00

Uploaded

2018 Feb 20 - 13:22

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Constellation

Grus

Field centre

RA: 22^h42^m
Dec: -46°49'
Position angle: +91°55'

Field size

0°11' × 0°14'

Equipment

Celestron C6
Wollaston Prism
Cousins V-Band filter
ATIK 314L+

Exposure

Various depending on target

Location

SW Scotland

Target name

Polarisation Standard Stars

Title

Polarimetry

About 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.

Files associated with this observation

PCAL.jpg (54.6 kB)

Like this image

Jeremy Shears, Dr Andrew Smith, Grant Privett, David Basey, Peter Carson, Matt Williams, David Salmon

Comments

Jeremy Shears, 2018 Feb 20 - 16:40 UTC

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

All the best,

Jeremy

Grant Privett, 2018 Feb 20 - 20:58 UTC

Really nice work.

Is the top chart the degree of linear polarisation?

Also, what filters did you use?

john simpson, 2018 Feb 20 - 22:54 UTC

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].

john simpson, 2018 Feb 20 - 22:56 UTC

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

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