Dome Inspector
From Halopedia, the Halo wiki
Dome Inspector
Dome Inspector is an Achievement in Halo 3: ODST. It is unlocked when the player gets 15 Headshot kills on the NMPD HQ Campaign level. It is worth 5 Gamerpoints.[1]
It is represented by a gold six-pointed star, with a purple colored skull with a circle with the number 15 in the circle.
Sources
http://www.youtube.com/watch?v=CtmODBqqw4c&feature=related
