The Dusty Pleiades Askar200 ASI2600mc

[Laurin Dave]

The Dusty Pleiades imaged from Berkshire..  taken over three moonless nights in October and early November with an Askar200/ASI2600mc combo mounted on anAZEQ6.  140 x 2 minute exposures at ZWO's LRN setting.  Processed in Pixinsight and Photoshop.  I used the latest WBPP script with the Split Channels option, after de-bayering this option splits the channels and registers all Red Green and Blue subs separately to the reference frame using thin plate splines and distortion correction.  Takes an age but  seems to me to produce somewhat better stars with less colour fringing than when registering the subs as RGB.  I also used the Normalise Scale Gradient script, which is worth a try out if you haven't done so already.  TGV and MMT noise reduction, HSVrepair  script, ArcSinh stretch followed by Histogram transformation and Masked stretch then into Photoshop for colour enhancement, a touch of Pixinsight LHE and masked curves to bring out the dust then a final dose of ACDNR in Pi, then resample to 50%. Have to say that I'm pretty pleased with this and the amount of dust, the sky measured mag 20.3 the night most of the subs were taken.    A bit of tilt showing lower left..

Thanks for looking

Dave

 

Edited November 4, 2021 by Laurin Dave

[gorann]

Excellent Dave! Dusty it is. Most of that PI hocus-pocus is unknown to me but I like the result.

[Laurin Dave]

15 minutes ago, gorann said:

Excellent Dave! Dusty it is. Most of that PI hocus-pocus is unknown to me but I like the result.

Thanks Goran, the NSG script (developed by John Murphy, who is a fellow member of Basingstoke Astro Soc) was particularly useful here, it uses stellar photometry to calculate the gradient difference between the target frame and the reference (your choice of best) frame and then subtracts it thereby normalising it the the reference,  it then weights the frame against the reference frame and writes the weight into the fits header. This weight is then used when Integrating the subs and helps mitigate the fact the the frames with the best SNR can also have the worst light pollution.  The resulting Integration just has the gradient associated with the reference frame, which being only 2 minutes long is easily removed with DBE points in just the corners.  

Worth a try out  (but for your dark skies probably only for when the moon is about - benefits moon-shot Ha too) 

Dave

[Lee_P]

This is a great image, and thanks also for sharing your processing workflow. One quick question that may help me, re NSG: how do you choose your reference frame? I tend to just pick one that has the best Stars or FWHM rating, but is there a better way?

[Laurin Dave]

8 minutes ago, Lee_P said:

This is a great image, and thanks also for sharing your processing workflow. One quick question that may help me, re NSG: how do you choose your reference frame? I tend to just pick one that has the best Stars or FWHM rating, but is there a better way?

Thanks @Lee_p, I measure the subs with Pi Subframe Selector and generally choose the sub with the lowest median value so long as its got a good FWHM and isn't an outlier.  It usually turns out to be the one shot highest in the sky on the darkest night if the subs are over multiple nights.