Remove Star Trailing
1. Make a copy of the background layer onto a second layer
2. Change the blending mode from Normal to Darken.
3. Click on the Move Icon, top of the tools column on the left.
4. Zoom in well. Then with the arrow keys, move one of the layers till the stars become round-ish.
5. Flatten the two layers into one.
6. You may have to brighten the final result to regain some lost light through the “darken” step.