Star trails are tri-color as the images have been registered on the comet itself.
Each R, G, B composite brings its stars with its corresponding colors. Note the very remarkable greenish color of comet Kopff 22P. Comments Observing conditions were excellent and the sea cloud deck level was settled 100 meters below the observatory at about 1000 meters. The glow of the French Riviera was completely covered by the cloud blanket and the sky was remarkably dark at the low declination where the object was observed at approximately -16 . Dawn was there when the last images were made preventing from grabbing at least one more green image.