Startrails are created by long exposure times of around 15 minutes to several hours. This records the apparent movement of the stars in the night sky due to the rotation of the earth.

A star trail photo shows the stars as arcs across the image, with longer exposures making longer arcs.

For a star trail recording, several longer-exposed photos are required. These have to be summarized in a summary photo on the computer with special SW, e.g. StarStaX.

In contrast to the photography of galactic nebulae or galaxies, the camera has not to be tracked here because the "movement of the stars" due to earth rotation is supposed to be shown.

If the camera points to north towards the north celestial pole, e.g. aligned with the polar star Polaris in the constellation Little Dipper, the stars in the picture "circle" around this celestial north pole.
If, on the other hand, the camera is oriented precisely to the south, horizontal star arcs are created, see pictures below.