De-Bayering or Dithering problem?

[fwm891]

I've been imaging the rosette (6x5 min subs) and I'm getting a linear pattern to the background.

 

Capture is via Maxim and I'm employing a dither of < 2pixels between exposures. No filteres have been used and the DSLR is unmodified.

 

Images have not been de-bayered, simply registered and stacked in PI then processed in PS-CS3.

 

My thoughts are that there is a resonance between the dithering and the rows/columns of pixels on the CCD. But it may be that I need to de-bayer the images?

 

Can anyone throw a light on this please

 

 

Part of a single sub:

Edited February 18, 2014 by fwm891