“First Light” with the BYU/NRAO Prototype 19 Element Focal Plane Array on the Green Bank 20 Meter Reflector Jonathan Landon, Jacob Waldron, David Jones, Allan Stemmons, Mike Elmer, Brian Jeffs, Karl Warnick – BYU Rick Fisher, Rich Bradley, and Roger Norrod - NRAO 19 element focal plane array (FPA) feed built by the BYU Radio Astronomy Lab was mounted on the 20 meter dish antenna at the National Radio Astronomy Observatory (NRAO) in Green Bank, WV and used for experimental observations from Oct. 31 to Nov. 7, 2007 FPAs allow electronic beamsteering for rapid sky surveys and adaptive cancellation of unwanted interfering signals that can disrupt sensitive astronomical observations Deep space sources were detected and signal levels were used to measure performance of the FPA Adaptive signal processing was used to cancel interfering signals successfully These results lay the groundwork for a future array feed that will improve scientific observation capability for radio astronomy This project is funded by the National Science Foundation