Current Detections on Rings and Streams in the Galactic Anti-Center

This passage is about a current study of the substructure around the Galactic anti-center.Since Newberg et al,(2002) first detected the overdensity around the Galactic anti-center,a flurry of papers started to research on this substructure.This paper will be a background information research on this substructure for the later work of the controversial substructure.