Observant
From Halopedia, the Halo wiki
Observant
Observant is an achievement in Halo: The Master Chief Collection. It is awarded for activating the twentieth Halo 3: ODST Audio log on Mombasa Streets. The achievement is worth 5 Gamerscore and can be unlocked on any difficulty.
Location[edit]
The achievement is awarded when the player unlocks their twentieth terminal, regardless of which terminal in the hub that is. For terminal locations, see here.