Aligning the Quadrant Detector Mount
Green Bank Engineers Ike Johnson (lying down at the finder scope) and Jeff Cromer are aligning the mount for the Green Bank Telescope’s quadrant detector. Ike is viewing a beam that has come from the feed arm of the GBT over 60 feet above them. In wind and temperature extremes, and under its own weight, the long feed arm sways. A laser from the arm gets aligned down to a reflector and into a rangefinder that helps the telescope operators know how well the GBT’s receivers are aligned to the waves bouncing up from the dish.