Rotational Gradient
The rotational gradient, also called Larson Sekanina filter, is a filter that allows to remove circular structures from an image, to better highlight other details.
Tip
This technique is particularly effective to show the jets coming out of the nucleus of a comet.
Warning
The first thing to do is to report the centroid coordinates in the X/Y text boxes. You can do this with a PSF or with the mouse coordinates displayed below the image.
Once done, you can increase the rotational offset (and the radial offset in a second step): the gradient removes the object with a rotational symmetry with respect to ([x], [y]). Make several tests using the undo/redo function but be careful when interpreting the results you see, they might be artifacts.
Example
