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Alignment issues and stack of wide field images from
https://www.reddit.com/r/astrophotography/comments/48wg8x/help_i_tried_to_capture_the_milky_way_tonight_but/
27 images selected, out of a larger set; some rejected due to vibration smear.
Figure 1. DSS from input using the full image out of the raw converter.
Output is the "calibrated" files, not aligned. This image shows
the star movement between frames due to the Earth's rotation.
Image is max combine (maximum intensity at each pixel in the image set).
Figure 2. Aligned images from DSS using the full image out of the raw converter.
Image is max combine (maximum intensity at each pixel in the image set)
to show the misalignment.
Figure 3. Image set cropped then aligned in ImagesPlus with translate + rotate,
then that result put into deep sky stacker, DSS, and auto aligned.
Image is max combine (maximum intensity at each pixel in the image set)
to show the misalignment.
Figure 4. The alignment effort from figure 3 was combined using sigma clipped average
in ImagesPlus, standard deviation = 1.95. This rejects the outer misaligned
stars, but loses many fainter stars and smears detail (e.g. in the galaxy M31).
A best effort. Convert raw with photoshop ACR, align with step 1:
ImagesPlus translate + rotate, then use DSS auto. Then stretch.
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http://www.clarkvision.com/articles/astrophotography-color-accuracy-and-light-pollution
First Published March 5, 2016
Last updated March 5, 2016