A Ghost telemetry link that speeds the development of your upgradeable Machine Guns. Lasts 30 minutes.
― In-game description

Machine Gun Telemetry is a consumable that increases the experience gained towards machine guns for 30 minutes.

Prior to Destiny: The Taken King, they could be purchased from Xûr or from dismantling upgraded legendary machine guns. After The Taken King, they were replaced by Heavy Telemetry.