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What am I looking at here?
This is a center crop from a stack of 5x10 minute luminance subs of NGC4038.
I'd add crops from the RGB as well but they just repeat the same sequence.
Here's my guess. It's a hot pixel that isn't taken out by the usual darks etc because it is moving from sub to sub. There are 5 bright spots with a gap between 2 and 4 (counting from the lop right) which corresponds to the fact that I ditched sub 3 because of a big jump. So I stacked 1,2,4,5,6. And this sequence shows that from one sub to the next the image has moved in a steady and regular pattern from top right to bottom left. The RGB subs continue the same pattern and take up from where the lum subs finished. So there is a pattern of regular and consistent movement that is occurring BETWEEN subs. i.e. one sub finishes, there is a pause for the download and guider settle - up to 20 seconds or so on my QSI CCD and in that period between subs, something happens to allow this drift.
I am guiding with MaximDL and imaging with it also.
Is this a sign of polar alignment that is off, tracking rate error, .... I'm out of guesses.
Anyone??
Peter
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