SEPIA – a new single pixel receiver 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: victor.belitsky@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 Netherlands Research School for Astronomy (NOVA), Kapteyn Astronomical Institute, Landleven 12, 9747 AD Groningen, The Netherlands

Received: 28 June 2017
Accepted: 19 November 2017

Abstract

Context. We describe the new Swedish-ESO PI Instrument for APEX (SEPIA) receiver, which was designed and built by the Group for Advanced Receiver Development (GARD), at Onsala Space Observatory (OSO) in collaboration with ESO. It was installed and commissioned at the APEX telescope during 2015 with an ALMA Band 5 receiver channel and updated with a new frequency channel (ALMA Band 9) in February 2016.

Aim. This manuscript aims to provide, for observers who use the SEPIA receiver, a reference in terms of the hardware description, optics and performance as well as the commissioning results.

Methods. Out of three available receiver cartridge positions in SEPIA, the two current frequency channels, corresponding to ALMA Band 5, the RF band 158–211 GHz, and Band 9, the RF band 600–722 GHz, provide state-of-the-art dual polarization receivers. The Band 5 frequency channel uses 2SB SIS mixers with an average SSB noise temperature around 45 K with IF (intermediate frequency) band 4–8 GHz for each sideband providing total 4 × 4 GHz IF band. The Band 9 frequency channel uses DSB SIS mixers with a noise temperature of 75–125 K with IF band 4–12 GHz for each polarization.

Results. Both current SEPIA receiver channels are available to all APEX observers.