Removing a Prime Focus Receiver
A telescope engineer inspects a receiver slotted into the cage at the Green Bank Telescope’s Prime Focus. This is where the radio waves come together after they have reflected off of the telescopes 100-meter dish.
The GBT’s huge metal feed arm towers 200 feet above the dish, ending in a retractable boom at the Prime Focus. Radio waves can pour directly into a receiver like this one cradled in a metal-framed box on the boom. The boom can tilt and twist to align the receiver perfectly to the incoming waves.