First supra-THz Heterodyne Array Receivers for Astronomy with the SOFIA Observatory

TL;DR

This paper introduces the first successful astronomical observations using supra-THz heterodyne array receivers on the SOFIA observatory, demonstrating advanced waveguide-based HEB mixer arrays for far-infrared astronomy.

Contribution

It presents the design, laboratory, and telescope characterization of the first supra-THz heterodyne array receivers, enabling high-frequency observations above 1 THz from an airborne platform.

Findings

First astronomical observations with a heterodyne focal plane array above 1 THz.

Successful operation of high-power closed-cycle coolers below 4.5 K on an airborne platform.

Demonstration of dual-polarization waveguide-based HEB mixer arrays for far-infrared astronomy.

Abstract

We present the upGREAT THz heterodyne arrays for far-infrared astronomy. The Low Frequency Array (LFA) is designed to cover the 1.9-2.5 THz range using 2x7-pixel waveguide-based HEB mixer arrays in a dual polarization configuration. The High Frequency Array (HFA) will perform observations of the [OI] line at ~4.745 THz using a 7-pixel waveguide-based HEB mixer array. This paper describes the common design for both arrays, cooled to 4.5 K using closed- cycle pulse tube technology. We then show the laboratory and telescope characterization of the first array with its 14 pixels (LFA), which culminated in the successful commissioning in May 2015 aboard the SOFIA airborne observatory observing the [CII] fine structure transition at 1.905 THz. This is the first successful demonstration of astronomical observations with a heterodyne focal plane array above 1 THz and is also the first time high- power closed-cycle coolers for temperatures below 4.5 K are operated on an airborne platform.