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R.Mon & NGC2261 Polarimetry


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About this observation
john simpson
Time of observation
24/02/2018 - 20:35
Observing location
SW Scotland
Celestron C6
Astrodon [J-C] V-band filter
ATIK 314L+
60 sec.
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R.Mon listed as Herbig Ae/Be star in Simbad. It’s the source of illumination/excitation of nebula NGC2611. The figure shows a composite of linear polarisation images taken at 0, 45, 90,135 deg. [20 exposures each of 60seconds]. The Wollaston prism splits the incoming beam into 2 orthogonally polarised beams from which are calculated Stokes Q & U as well as linear polarisation magnitude and angle. Considerable debate in the past about the nature and geometry of the polarised gas & dust surrounding R.Mon as a result of the large variations in measured polarisation magnitude & angle on time-scales of months/years. Typically these have ranged from 10-15% and 70-100 deg. respectively.   This target probably the limit of what I can measure. Also had some problems with tripod & tracking, hence the oval stars, but still enough data to measure the polarisation. In this instance R.Mon magnitude estimated to be 13.9% with polarisation ellipse at an angle of 65.3 deg.  Still looking at how [and if possible] to extract polarisation characteristics of  the nebula. All good fun though.

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