SEPIA345: A 345 GHz dual polarization heterodyne receiver channel for SEPIA at the APEX telescope

¹ Group for Advanced Receiver Development (GARD), Department of Space, Earth and Environment, Chalmers University of Technology, 41296 Gothenburg, Sweden
e-mail: denis.meledin@chalmers.se
² Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory (OSO), 43992 Onsala, Sweden
³ European Southern Observatory (ESO), Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
⁴ European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla 19001 Santiago de Chile, Chile
⁵ Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura 763-0355 Santiago de Chile, Chile
⁶ Departamento de Física de la Tierra y Astrofísica, Universidad Complutense de Madrid, 28040 Madrid, Spain
⁷ Instituto de Física de Partículas y del Cosmos IPARCOS, Fac. de Ciencias Físicas, Univ. Complutense de Madrid, 28040 Madrid, Spain

Received: 7 June 2022
Accepted: 17 September 2022

Abstract

Context. We describe the new SEPIA345 heterodyne receiver channel installed at the Atacama Pathfinder EXperiment (APEX) telescope, including details of its configuration, characteristics, and test results on sky. SEPIA345 is designed and built to be a part of the Swedish ESO PI Instrument for the APEX telescope (SEPIA). This new receiver channel is suitable for very high-resolution spectroscopy and covers the frequency range 272–376 GHz. It utilizes a dual polarization sideband separating (2SB) receiver architecture, employing superconductor-isolator-superconductor mixers (SIS), and provides an intermediate frequency (IF) band of 4–12 GHz for each sideband and polarization, thus covering a total instantaneous IF bandwidth of 4 × 8 = 32 GHz.

Aims. This paper provides a description of the new receiver in terms of its hardware design, performance, and commissioning results.

Methods. The methods of design, construction, and testing of the new receiver are presented.

Results. The achieved receiver performance in terms of noise temperature, sideband rejection, stability, and other parameters are described.

Conclusions. SEPIA345 is a commissioned APEX facility instrument with state-of-the-art wideband IF performance. It has been available on the APEX telescope for science observations since July 2021.