Commissioning of FLAG: A phased array feed for the GBT
  Phased Array Feed (PAF) technology is the next major advancement in radio
astronomy in terms of combining high sensitivity and large field of view. The
Focal L-band Array for the Green Bank Telescope (FLAG) is one of the most
sensitive PAFs developed so far. It consists of 19 dual-polarization elements
mounted on a prime focus dewar resulting in seven beams on the sky. Its
unprecedented system temperature of$\sim$17 K will lead to a 3 fold increase in
pulsar survey speeds as compared to contemporary single pixel feeds. Early
science observations were conducted in a recently concluded commissioning phase
of the FLAG where we clearly demonstrated its science capabilities. We observed
a selection of normal and millisecond pulsars and detected giant pulses from
PSR B1937+21.
