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In need of advice

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#1 paulking

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Posted 29 February 2020 - 12:56 AM

Been trying to use WBPP in Pixinsight and my problem is after stacking my Green integrated master contains a lot of noise and "Bok globules" , much noisier than the single green filter sub. I've used the standard WBPP settings except for Windsorized sigma clipping instead of auto, which returned the same result anyway. No doubt Ive got something wrong somewhere.lol.gif

 

Paul

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Edited by paulking, 29 February 2020 - 03:04 AM.


#2 Stelios

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Posted 29 February 2020 - 01:27 AM

Not enough information. Did you dither? Did you use calibration frames? Did you blink bad frames away?

 

The image you posted is too small to make anything out. You are allowed up to 500KB in uploads. 



#3 jerahian

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Posted 29 February 2020 - 01:41 AM

That looks like walking noise to me. Are you dithering in RA only perchance? If so, you should be dithering in both RA and Dec. Also, if you are dithering in both, you may not be dithering enough.

Basically, what you’re seeing here is noise which PI has determined is valid signal, which walks across your integrated image if the dithering is not appropriately configured.

#4 paulking

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Posted 29 February 2020 - 03:15 AM

Thanks Stelios,  Jerahian, In PHD2 I have the dither on random and the default value of 1, and the green channel is most effected...yes used all calibration frames...the subs all look good through Blink..never encountered this issue before.

 

Paul



#5 klaussius

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Posted 29 February 2020 - 10:55 AM

Thanks Stelios,  Jerahian, In PHD2 I have the dither on random and the default value of 1, and the green channel is most effected...yes used all calibration frames...the subs all look good through Blink..never encountered this issue before.

 

Paul

1px dither is way too little with most CMOS cameras. You have to measure the average distance between hot-ish (inspect your darks) pixels and use that as your dither size.



#6 RJF-Astro

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Posted 29 February 2020 - 12:01 PM

I agree on the dithering, but maybe try DSS to be certain it is not a stacking error? And what calibration files did you use? I have had similar results with bad flats or bias with my ASI1600.

#7 WebFoot

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Posted 29 February 2020 - 12:26 PM

I have nothing to add to the probable cause, but I would say that my first trouble-shooting step would be to manually create the green master, by (i) create your master dark and master bias; (ii) calibrate your individual flats; (iii) create your master flat; (iv) calibrate your light frames; (v) do cosmetic correction on your light frames; (vi) blink through the registered light frames to see if any are bad; (viii) run your registered light frames through subframe selector to see if any should be tossed; (ix) integrate your light frames.

Of course, if you've made a mistake on, e.g., whether to calibrate your master dark/bias, you'll still have some issues.

I'm a glutton for punishment, but I stopped using Batch Preprocessing some time ago, because it didn't give me enough step-by-step control over the process.

Good luck!

 

Mark




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