Performance of a highly sensitive, 19-element, dual-polarization, cryogenic L-band Phased Array Feed on the Green Bank Telescope

Abstract

A new 1.4 GHz 19-element, dual-polarization, cryogenic phased array feed (PAF) radio astronomy receiver has been developed for the Robert C. Byrd Green Bank Telescope (GBT) as part of FLAG (Focal L-band Array for the GBT) project. Commissioning observations of calibrator radio sources show that this receiver has the lowest reported beamformed system temperature ($T_{\mathrm{sys}}$) normalized by aperture efficiency ($\eta$) of any phased array receiver to date. The measured $T_{\mathrm{sys}}/\eta$ is $25.4\pm 2.5$ K near 1350 MHz for the boresight beam, which is comparable to the performance of the current 1.4 GHz cryogenic single feed receiver on the GBT. The degradation in $T_{\mathrm{sys}}/\eta$ at $\sim$ 4 arcmin (required for Nyquist sampling) and $\sim$ 8 arcmin offsets from the boresight is, respectively, $\sim$ 1\% and $\sim$ 20\% of the boresight value. The survey speed of the PAF with seven formed beams is larger by a factor between 2.1 and 7 compared to a single beam system depending on the observing application. The measured performance, both in frequency and offset from boresight, qualitatively agree with predictions from a rigorous electromagnetic model of the PAF. The astronomical utility of the receiver is demonstrated by observations of the pulsar B0329+54 and an extended HII region, the Rosette Nebula. The enhanced survey speed with the new PAF receiver will enable the GBT to carry out exciting new science, such as more efficient observations of diffuse, extended neutral hydrogen emission from galactic in-flows and searches for Fast Radio Bursts.

arXiv comment24 pages, 16 figures, to appear in Astronomical Journal

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Cited by in corpus (8)

• The Future of Fast Radio Burst Science
• Enhanced Rates of Fast Radio Bursts from Galaxy Clusters
• An International Survey of Front-End Receivers and Observing Performance of Telescopes for Radio Astronomy
• Commissioning the HI Observing Mode of the Beamformer for the Cryogenically Cooled Focal L-band Array for the GBT (FLAG)
• Characterising the Apertif primary beam response
• A 21 cm pilot survey for pulsars and transients using the Focal L-Band Array for the Green Bank Telescope
• Enabling Discoveries: Thirty Years of Advanced Technologies and Instrumentation at the National Science Foundation
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