M42 first attempt (and all the warts) 10.12.09 Back garden

[MarkS]

Better than a diagram is the actual data - here is a raw stack of 38 five minute subs.  The guidestar was just off the right of the picture - the other stars rotate around it:



The image below (again from the raw stack) shows the vertical striations (an artifact of the CCD/camera electronics).  In the areas of the raw stack where the smears align with the striation, the striation will never be averaged away during the registering and stacking process.



I have now created a processing sequence that removes these striations but it is not at all easy.  It involves "reverse engineering" a frame containing the striations only and then subtracting it from each sub.

Mark

[Rocket Pooch]

I'm getting an OAG to stop this from happening, after I prove the current batch of flatteners etc, I'm fed up with flexture etc....

[MarkS]

How would an Off Axis Guider help?  The rotation in that image took place over a 3 hour period - it was due to polar alignment being slightly off.  Each individual sub was fine and, after alignment, they stacked together fine EXCEPT there was no dithering to get rid of the vertical striations in the CCD pattern (due to a bug in that particular version of Nebulosity).

The point I was making is that in the image areas where (vertical) smears align with the (vertical) striation, the striation will never be averaged away during the registering and stacking process.

Mark

[Carole]

Very interesting Mark, thanks for that. 

Carole