M37 - Open Cluster in Auriga

M37 (NGC2099) is one of three open clusters in the constellation of Auriga cataloged by Messier.   The other two are M36 and M38.   

Sharp-eyed observers may note a small blue and green streak in the bottom center of the image.   This streak is asteroid (776) Berbericia shining at magnitude 11.7 as it moved through the scene during the blue and green frames.  Why are there no red or white streaks?   The red and luminance frames were taken the night before and the asteroid was not in the field.