Every other frame FHWM all over the place?

Sequence Generator
1

So I noticed this last night. Very odd behavior.

I was shooting short 60 second frames of M11 and I noticed that with the Lum filter the FHWM was showing a distinct pattern, every other frame was ‘good’ the ones in between were not so good!?

Bah flickr cuts off the screen I will edit in a better view shortly. In the meantime you can click the image for a full view.

SGP IH by Tom Whit, on Flickr

SGP IH by Tom Whit, on Flickr

2

Here is what PixInsight things of the frames!

PI graph by Tom Whit, on Flickr

3

Never mind… mystery solved.

Evidently the sequence had two runs on the lum channel one at 120 sec and another at 60 seconds…

Kind of embarrising !