Using the software Sequator156 to stack 56 consecutive photos into star trails.
The shooting time is January 31, 2023, 03:00 am~03:19 am.

The Color of the Stars
This one is a field of view at a focal length of 70mm near Polaris, with a total of about 19 minutes of star trails. It can be seen that the colors of the stars are very rich! The color of a star is related to its surface temperature. Red stars are cooler, and blue-white stars have higher surface temperatures.
The bright green in the center is the trail of comet C/2022 E3 ZTF. Since there are no green stars, the comet's green color is relatively very apparent throughout the picture! In addition, the nucleus of the comet is actually a clump rather than a point, so it can also be seen from the picture that the green track of the comet is thicker than that of other stars.
In addition, it can be found that Polaris is not at the center of the concentric circles. This means that Polaris is still slightly off from the true North Pole.