Hi,
If you are seeing "double stars" then the StarAlignment had an issue. I had a similar problem and the issue was that my stars were not correctly focused. Have a look at my post "Mosaic of a Mosaic not aligning correctly"
Juan Conejero had this solution which worked perfectly:
The problem with these images is that they are out of focus. The new distortion correction algorithm implemented in StarAlignment requires accurate PSF fits for robust star detection. Unfocused stars have irregular distributions and flat profiles, which makes centroid determination uncertain. With its default parameters, SA cannot compute a valid local distortion model for these images.
However, you can tweak a couple of parameters to register these mosaics very accurately (to the accuracy that is achievable with out-of-focus images, that is):
- Set the peak response parameter to 1 (Star Detection section). This is necessary because the stars in these images are flat with relatively weak peaks, so SA's star detector must be more peak-sensitive than usual to detect some of them.
- Click the Edit Instance Source Code button (empty square, bottom right corner).
- On the source code editor window, look for the psfTolerance parameter. Its default value is 0.5 pixels:
Code:
P.psfTolerance = 0.50;
Change it to 2 pixels:
Code:
P.psfTolerance = 2;
- Click the Commit button (green check mark, top right corner).
- Set Registration model to Thin Plate Splines.
- Enable the Distortion correction and Local distortion options.
- Select the Ha image as registration reference.
- Apply the process to the OIII image.
- Use ChannelCombination with the Ha image and the registered OIII image.
spaceisnotblack
John