Here is a picture by Mike Salway, from New South Wales, Australia. Several of his pictures have been featured in NASA's Astronomy Picture of the Day.

To isolate the upper end of the star trails, subtract the original from a shifted copy of the original. In this case, the shift is 2 left and 3 up. Move your mouse over the image below to see the top ends of the star trails.

Notice the diagonal band starting in the upper-right of the mouse-over image where the trails are extinguished and all that is left are the stars. All of the trails cannot be removed in this way because the star trails are curved, and their slope is not constant throughout the entire image. We could have done better if we had rotated and shifted, but the rotation needed for this is smaller than .1 degree, which is the smallest rotation that Photoshop will do. Closer to the poles, rotation becomes more important.



Identify the field by running the upper part of the image below through the astrometry.net code and plot the field identified with Voyager. Move your mouse over the image below to see the Voyager output.



Move your mouse over the Voyager image below to superimpose the original image.



Finally, we have the finished product. Move your mouse over the original image below to add the annotations.