In astrophotography, dithering is a technique used to reduce the impact of noise and other unwanted artifacts in an image. It involves small, random movements of the telescope or camera between exposures, which causes the stars and other objects in the image to move slightly from one frame to the next. This movement is used to improve the final image quality by reducing the effects of fixed-pattern noise, hot pixels, and other imperfections that can occur in digital images.

Dithering is most commonly used when taking multiple exposures of the same object, such as during a long imaging session. By dithering the telescope or camera between each exposure, the final image will have a higher signal-to-noise ratio, which can result in better detail and color accuracy.

The amount and frequency of dithering can vary depending on factors such as the imaging equipment, the object being photographed, and the desired final image quality. Some astrophotography software programs, such as PHD2 and N.I.N.A, include dithering features that can automate the process and optimize the results.