The observer is a small aerospace drone used to survey space and record events for analysis in the protoss archives.[1][2] The complex sensor array is power intensive but may detect cloaked and concealed objects.[2]
Observers may be equipped for warp space travel and deployed for deep-space exploration.[3] Units used for this purpose often lack defensive systems.[2] They may re-enter real space within planetary atmospheres and transmit data in real-time over interstellar distances. In addition observers may drop navigational beacons as homing devices.[3]
The sensitive sensor system,[2] sophisticated enough to even detect zergspores within terrans,[4][5] makes the observer a valuable auxiliary on the battlefield. Units intended for combat zones are equipped with a defensive micro-cloaking field. The sensor signature of the drone reduces the field's power requirement and allows the cloak to be maintained for extended periods[2] with little drain to its power core.[6]
Game Unit
StarCraft
Observers are the protoss' mobile detectors. Although observers are 'permanently' cloaked protoss players must be more alert to enemy anti-cloak units; the observer's low health gives little time to escape attackers. Observers are cheap enough to have a handful accompany an attack force, especially against a target with many detectors.
The following section contains information from a previous version of StarCraft II which is no longer valid.
In a September 2008 build of StarCraft II, the observer did not require an observatory to build, making it available earlier in the tech tree than in StarCraft. It was upgraded at the null circuit.[8]