Daniel_Sp
October 12th, 2016, 07:48 PM
Hello everybody,
although M1 is an "everyday object", this topic would fit into the board "Off the beaten path" as well, because the imaging/sketching technique is really far off the beaten path!
So... it started with the homepage of Richard Crisp, who mapped the Stokes Parameter of several objects by photography:
http://www.narrowbandimaging.com/color_polarization_imaging_page.htm
I simply had to know, if it is possible to get any results visually. I made 5 sketches of M1 during the HTT (a german starparty; "Herzberger Teleskoptreffen) two weeks ago. The 1st sketch without Filter, only a 10mm - eyepiece (TV Delos) in my 24" dobsonian with 252x. Afterwards, I added a polarization filter and made 4 other sketches at different, but well known polarizer angles: 0°, 45°, 90° and 135°. For further information about the Stokes Parameter, please check out the wikipedia site... Finally, I had the same workflow as I described in "M27 in bicolor", but I had more possibilities, as you can see in the following images:
2301
1. The image shows the distribution of the max. polarization angle in rad - but only the linear components of the light. Note the scale on the right.
2302
2. This is the final Stokes Parameter Map as LRGB-composite. L = observation sketch without filter = S_0, red = S_1, green = S_2, blue = S_3
BTW: the sketches were made on transparency paper, that got quickly wavy as you can see around the nebula...
Since it was not possible to observe only the circular polarized light which are required for S_3, this Parameter can be calculated by
S_3 = sqrt{(S_0)² - (S_1)² - (S_2)²}.
Therefore, the first image contains linear components only. If circular components were not neglected, everything would cancel out...
Best regards + CS
Daniel
although M1 is an "everyday object", this topic would fit into the board "Off the beaten path" as well, because the imaging/sketching technique is really far off the beaten path!
So... it started with the homepage of Richard Crisp, who mapped the Stokes Parameter of several objects by photography:
http://www.narrowbandimaging.com/color_polarization_imaging_page.htm
I simply had to know, if it is possible to get any results visually. I made 5 sketches of M1 during the HTT (a german starparty; "Herzberger Teleskoptreffen) two weeks ago. The 1st sketch without Filter, only a 10mm - eyepiece (TV Delos) in my 24" dobsonian with 252x. Afterwards, I added a polarization filter and made 4 other sketches at different, but well known polarizer angles: 0°, 45°, 90° and 135°. For further information about the Stokes Parameter, please check out the wikipedia site... Finally, I had the same workflow as I described in "M27 in bicolor", but I had more possibilities, as you can see in the following images:
2301
1. The image shows the distribution of the max. polarization angle in rad - but only the linear components of the light. Note the scale on the right.
2302
2. This is the final Stokes Parameter Map as LRGB-composite. L = observation sketch without filter = S_0, red = S_1, green = S_2, blue = S_3
BTW: the sketches were made on transparency paper, that got quickly wavy as you can see around the nebula...
Since it was not possible to observe only the circular polarized light which are required for S_3, this Parameter can be calculated by
S_3 = sqrt{(S_0)² - (S_1)² - (S_2)²}.
Therefore, the first image contains linear components only. If circular components were not neglected, everything would cancel out...
Best regards + CS
Daniel