The 17–27 GHz Dual Horn Receiver on the NASA 70 m Canberra Antenna

Abstract

A dual beam, dual polarization, low noise receiver has been installed at a Cassegrain focus of the NASA 70[Formula: see text]m antenna near Canberra, Australia. It operates in five pairs of 1[Formula: see text]GHz bands from 17 to 27[Formula: see text]GHz simultaneously. The receiver temperature measured at the feed is 21–22[Formula: see text]K at 22[Formula: see text]GHz and, during dry winter night-time conditions, zenith system temperatures as low as 35[Formula: see text]K have been observed in the 21–22[Formula: see text]GHz band. The native polarization is linear but can be converted to circular prior to down-conversion. The downconverters have complex mixers, followed by quadrature hybrids which can be bypassed or used to convert the quadrature phase channels into an upper and lower sideband, each 1000[Formula: see text]MHz wide. For spectroscopy, four ROACH1 signal processors each currently providing 32[Formula: see text]K channel spectra across four 1000[Formula: see text]MHz bands, for 0.4[Formula: see text]km/s velocity resolution at 22[Formula: see text]GHz. Using both beam- and position-switching, the receiver achieved a noise level of 5[Formula: see text]mK r.m.s. in an hour of integration and 31[Formula: see text]kHz resolution. The NASA 70[Formula: see text]m antennas have a 45 arcsec beamwidth at 22[Formula: see text]GHz and an aperture efficiency of 35.5% giving a sensitivity of 0.49[Formula: see text]K/Jy.

A Broadband Digital Spectrometer for the Deep Space Network

“…On 2019 November 24 we observed eight RRLs simultaneously, from H70α to H63α, each in two polarizations. The intensities obtained for the hydrogen recombination lines in Orion KL are consistent with those observed by Gong et al (2015) with Effelsberg 100 m telescope, for a main-beam efficiency of 0.5 and n S T A *= 1.9 Jy K −1 (Kuiper et al 2019). Note the difference in frequency response for each IF is caused by the front end K-band system (see Figure 6 in Kuiper et al 2019).…”

“…The intensities obtained for the hydrogen recombination lines in Orion KL are consistent with those observed by Gong et al (2015) with Effelsberg 100 m telescope, for a main-beam efficiency of 0.5 and n S T A *= 1.9 Jy K −1 (Kuiper et al 2019). Note the difference in frequency response for each IF is caused by the front end K-band system (see Figure 6 in Kuiper et al 2019). A powerful application for the spectrometer presented here is the possibility of stacking different RRLs to significantly improve the signalto-noise ratio of these observations, enabling the detection of faint lines, or for efficient OTF mapping over large spatial scales.…”

“…The 70m antenna Deep Space Station 43 (DSS-43, also known as "Tidbinbilla 70 m") at the Canberra Deep Space Communications Complex (CDSCC) within NASA's Deep Space Network is equipped with a K-band radio astronomy system. Operating over the 17 GHz to 27 GHz frequency range, the analog portion of the K-band system produces 40 IFs, each of 1 GHz bandwidth (Kuiper et al 2019). These IFs from the Wide Band Down Converter (WBDC) at DSS-43 are distributed to the new spectrometer.…”

Second Epoch ALMA Observations of 321 GHz Water Maser Emission in NGC 4945 and the Circinus Galaxy

“…H 2 O maser spectra of the galaxies in the 6 16 − 5 23 transition (ν rest =22.23508 GHz) were obtained using NASA Deep Space Network 70-m antenna at Tidbinbilla, DSS-43. Observations of the masers from June 2012 to April 2014 were conducted using a K-band receiver and ATNF correlator with a 64 MHz bandwidth, 2048 spectral channels, and dual circular polarization at a spectral resolution of 31.25 kHz or 0.42 km s −1 (Hagiwara et al 2013(Hagiwara et al , 2016, and observations from April 2016 to May 2017 were conducted using a new K-band receiver and SAO Spectrometer with a 1 GHz bandwidth, 32000 spectral channels, and dual circular polarization (Kuiper et al 2019) at a spectral resolution of 31.25 kHz or 0.42 km s −1 . We used a velocity resolution of better than ∼1 km s −1 to avoid blending of different velocity features.…”

“…We used a velocity resolution of better than ∼1 km s −1 to avoid blending of different velocity features. We adopted a telescope sensitivity of 2.6 Jy K −1 to convert antenna temperature to flux density with a conservatively estimated uncertainty in the flux density of 50%, as stated in the Tidbinbilla 70 m radio telescope guide 3 or in Kuiper et al (2019). Data reduction, including baseline calibration, averaging the two circular polarizations, and flagging bad scans when required were carried out using GBTIDL 4 All velocities in the final plots are then converted relative to the Local Standard of Rest using the optical definition.…”