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M81 from Paris suburbs with rather good seeing


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last week I had a  night of rather good seeing  over Paris for the first time since mid-September  (median FWHM 2.04" after stacking), with low transparency and invasive moonlight however.

I acquired 4 hours of luminance on M81 with an ASI183mm and my 200/800 Newtonian astrograph. The RGB data is from last year with an ASI1600mm.  The resolution is much better than in last year luminance, thanks to the tighter sampling of the ASI183 compared to the ASI1600 (0.65"/pix vs. 1"/pix)


Here's the result (right click for full resolution):



Clear skies,



Technical details

200/800 custom Newtonian astrograph with Romano Zen optics and carbon fiber tube
AP900 CP4 mount on Losmandy HD tripod
TS 2.5" Riccardi-Wynne corrector
ZWO LRGB filters
Guiding : ZWO OAG + ASI120mm mini + AsiairV1
Luminance : 240 *60sec with the ASI183mm
Chrominance : 40*60sec for each R, V and B filter with the ASI1600mm
Conditions : Bortle 7/8 skies in Paris' suburbs (20km from the Eiffel tower), decent seeing (2.04" FWHM), gibbous moon, lot of humidity
Processing with Pixinsight


Edited by Dan_Paris
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Thanks a lot Maximidius!


15 minutes ago, Maximidius said:

Your newt looks to be extremely well collimated. 

It was actually the first image I took after having dismantled completely the telescope for cleaning the mirrors. Thankfully, the Catseye tools are precise enough to get the collimation spot on without further tweaking.

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