WBPP not fully removing dust motes

Grant Smith

Hi Adam,

I've spent the weekend working through the FastTrack Tutorials and all the WBPP 2.0 Tutorials and have got some good results with old data. However, when I tried to pre-process some data from last night, it turned out I had a couple of dust motes but the process looks like it may be under-correcting as it doesn't seem to be fully removing them (or all of the corner vignetting, especially bottom right). 

Below are images of the Flat, Calibrated Light and Uncalibrated Light and you can see the motes on all of them (the Lights are blurrier as I was dithering my 31 total Light Subs). I used a total of 50 of each Flat, DarkFlat and Dark and the motes are on all of the Lights and Flats. My workflow is as per the tutorial for my ZWO CMOS camera i.e. Flat + DarkFlat and Light + Dark (no BIAS frames).

I'm after any advice of either what I am likely to be doing wrong or how would be best to go about fixing it as the motes show up even more when I start processing with DBE etc.

Thanks

Grant

BlockHead

Hi Grant,

You are being a little tricky here! Look closely as your raw (uncalibrated) image. There isn't a distinct donut near the left side of the galaxy. However, in your calibrated image there *is* something that is in the flat field image (and so show up in the calibrated image). Basically this appears that your optical system changed in some ways between the time that you took the data and the flat. 

I would compare motes, their numbers and positions. They have to match in each raw and calibrated frame exactly... otherwise it is tell you something is changing. 

These cameras are very very sensitive and the slightest thing messes things up. You didn't show a screen capture of the WBPP control panel..but I will assume there isn't a calibration error. (You meant to write Flat - (Flat) Dark and Light-Dark in the above.)

-the Blockhead

Grant Smith

Thanks for the response Adam, I really can't work out what I did wrong here but I had a go last night and got over 6 hours of integration time with no motes so I have a much better set of data to work with :). 

If I feel adventurous sometime I might have a go at adding both sets of data together, match the appropriate calibration frames and try the GAME approach you outline in one of your tutorials to reject the mote infested areas now I have 93 good frames vs. 31 impaired frames.

Thanks again

Grant

BlockHead

Great! Yes, Selective rejection will do the trick for you. You should try it...it is a good lesson and thing to know.

(and if it is impressive..I would enjoy using it as an example!)

-the Blockhead

Grant Smith

That sounds like a plan, I'll see how I get on. I've just seen your video go up on WBPP2.1 so I'll wait for that to drop for us and then I can try the new multi-night/Grouping functionality in that too!

Grant