It measures the surface of the GBT's primary reflector using a comparison between signals obtained from the antenna under evaluation and a test source (either a satellite based signal or astronomical source). The data and subsequent maps produced are then used to determine if and where adjustments are needed to the active surface panels so that a reasonably perfect parabola is obtained.
A schematic illustrating signal flow through the Holography Receiver and its various components is shown.
The GBT operator is responsible for assisting the Green Bank staff in carrying out testing and measurements using the Holography Receiver. Refer to the GBT Operations Manual, procedures and checklists for specific guidance on setting up and operating this complex system.