Attn: Louie

Louie,
Hi! Can you help me figure out something? I found my grandfather's separation sheets and I'm confused on what this means. It is under the Decorations and Citations part it says GO 6 HQ 494TH AAA GUN BN 45. By any chance can you tell me what the "GO 6" and the "45" mean? Also can you tell me what an ASR score is? Thanks!
Ashley