SArdinia Roach2-based Digital Architecture for Radio Astronomy (SARDARA)

Abstract

The Sardinia Radio Telescope (SRT) is a 64-m, fully-steerable single-dish radio telescope that was recently commissioned both technically and scientifically with regard to the basic observing modes. In order to improve the scientific capability and cover all the requirements for an advanced single-dish radio telescope, we developed the SArdinia Roach2-based Digital Architecture for Radio Astronomy (SARDARA), a wide-band, multi-feed, general-purpose, and reconfigurable digital platform, whose preliminary setup was used in the early science program of the SRT in 2016. In this paper, we describe the backend both in terms of its scientific motivation and technical design, how it has been interfaced with the telescope environment during its development and, finally, its scientific commissioning in different observing modes with single-feed receivers.

The flickering nuclear activity of Fornax A

“…SRT: 5.7 GHz -6.9 GHz Fornax A was observed with the SRT on January 26 and February 7, 2017. These observations were conducted in the context of the development of the spectral-polarimetric wide-field imaging of the SARDARA backend (SArdinia Roach2-based Digital Architecture for Radio Astronomy; Melis et al 2018). The total observing time on target was 4.5 hours.…”

Strong Evidence of Anomalous Microwave Emission from the Flux Density Spectrum of M31

“…With its 64 m primary mirror, the SRT, at 6.7 GHz, has a beam primary lobe width at half maximum (FWHM) of ≃2 ′ .9. Among the backends currently available, we used the SArdinia Roach2-based Digital Architecture for Radio Astronomy (SARDARA) backend (Melis et al 2018), a wide band digital backend, based on the ROACH2 1 technology, which can divide the signal in the given bandwidth into up to 16,384 channels for full Stokes spectropolarimetric observations.…”

“…We analyzed a set of different maps ranging from radio to IR frequencies in order to extract the integrated flux density from M31 to be compared with the C-band observations presented in this work. At frequencies below the C-band, we used L-band measurements at 1.4 GHz obtained with the SRT during SARDARA commissioning (Melis et al 2018). In order to monitor only the continuum radio emission from Andromeda, we filtered out the 1.4 GHz signal from neutral hydrogen arising from both our Galaxy and M31, excluding the frequency range 1420.65 MHz-1423.9 MHz.…”

“…Left panel: continuum map obtained at 6.7 GHz with the SRT. White contours refer to the SRT image at 1.4 GHz(Melis et al 2018) (levels start at 90 mJy/beam and scale by √ 2). Right panel: the same map is shown after removing the point sources.…”

Duty cycle of the radio galaxy B2 0258+35

“…The FWHM of the beam at this frequency is 2.9 arcmin so we set the telescope scanning speed to 6 arcmin s −1 and the scan separation to 0.7 arcmin to properly sample the beam. Full Stokes parameters were recorded with the SARDARA backend (SArdinia Roach2-based Digital Architecture for Radio Astronomy; Murgia et al 2016;Melis et al 2018). The correlator configuration was set to 1024 frequency channels of approximately 1.46 MHz for a total bandwidth of 1500 MHz.…”