Out-Of-Focus Holography Tool for the Sardinia Radio Telescope

This document represents a short guide to the out-of-focus holography package for the SRT

The Parkes Galactic Meridian Survey: observations and CMB polarization foreground analysis

We present observations and cosmic microwave background (CMB) foreground analysis of the Parkes Galactic Meridian Survey, an investigation of the Galactic latitude behaviour of the polarized synchrotron emission at 2.3 GHz with the Parkes Radio Telescope. The survey consists of a 5◦ wide strip along the Galactic meridian l = 254◦ extending from the Galactic plane to the South Galactic pole. We identify three zones distinguished by polarized emission properties: the disc, the halo and a transition region connecting them. The halo section lies at latitudes |b| > 40◦ and has weak and smooth polarized emission mostly at large scale with steep angular power spectra of median slope βmed ∼ −2.6. The disc region covers the latitudes |b| < 20◦ and has a brighter, more complex emission dominated by the small scales with flatter spectra of median slope βmed = −1.8. The transition region has steep spectra as in the halo, but the emission increases towards the Galactic plane from halo to disc levels. The change of slope and emission structure at b ∼ −20◦ is sudden, indicating a sharp disc–halo transition. The whole halo section is just one environment extended over 50◦ with very low emission which, once scaled to 70 GHz, is equivalent to the CMB B-mode emission for a tensor-toscalar perturbation power ratio rhalo = (3.3 ± 0.4) × 10−3. Applying a conservative cleaning procedure, we estimate an r detection limit of δr ∼ 2 × 10−3 at 70 GHz (3σ confidence limit) and, assuming a dust polarization fraction of <12 per cent, δr ∼ 1 × 10−2 at 150 GHz. The 150-GHz limit matches the goals of planned sub-orbital experiments, which can therefore be conducted at this high frequency. The 70-GHz limit is close to the goal of proposed next-generation space missions, which thus might not strictly require space-based platformsThis work has been partly supported by the project SPOrt funded by the Italian Space Agency (ASI) and by the ASI contract I/016/07/0 COFIS. MH acknowledges support from the National Radio Astronomy Observatory (NRAO), which is operated by Associated Universities Inc., under cooperative agreement with the National Science Foundatio

Status report of the SRT radiotelescope control software: the DISCOS project

The Sardinia Radio Telescope (SRT) is a 64-m fully-steerable radio telescope. It is provided with an active surface to correct for gravitational deformations, allowing observations from 300 MHz to 100 GHz. At present, three receivers are available: a coaxial LP-band receiver (305-410 MHz and 1.5-1.8 GHz), a C-band receiver (5.7-7.7 GHz) and a 7-feed K-band receiver (18-26.5 GHz). Several back-ends are also available in order to perform the different data acquisition and analysis procedures requested by scientific projects. The design and development of the SRT control software started in 2004, and now belongs to a wider project called DISCOS (Development of the Italian Single-dish COntrol System), which provides a common infrastructure to the three Italian radio telescopes (Medicina, Noto and SRT dishes). DISCOS is based on the Alma Common Software (ACS) framework, and currently consists of more than 500k lines of code. It is organized in a common core and three specific product lines, one for each telescope. Recent developments, carried out after the conclusion of the technical commissioning of the instrument (October 2013), consisted in the addition of several new features in many parts of the observing pipeline, spanning from the motion control to the digital back-ends for data acquisition and data formatting; we brie y describe such improvements. More importantly, in the last two years we have supported the astronomical validation of the SRT radio telescope, leading to the opening of the first public call for proposals in late 2015. During this period, while assisting both the engineering and the scientific staff, we massively employed the control software and were able to test all of its features: in this process we received our first feedback from the users and we could verify how the system performed in a real-life scenario, drawing the first conclusions about the overall system stability and performance. We examine how the system behaves in terms of network load and system load, how it reacts to failures and errors, and what components and services seem to be the most critical parts of our architecture, showing how the ACS framework impacts on these aspects. Moreover, the exposure to public utilization has highlighted the major flaws in our development and software management process, which had to be tuned and improved in order to achieve faster release cycles in response to user feedback, and safer deploy operations. In this regard we show how the introduction of testing practices, along with continuous integration, helped us to meet higher quality standards. Having identified the most critical aspects of our software, we conclude showing our intentions for the future development of DISCOS, both in terms of software features and software infrastructures. <P /

Dish Washer: a Software Tool for RFI Mitigation in Single-dish Radio Astronomical Observations

Radio Frequency Interference is one of the most pressing problems in cm-wavelength world-wide radio astronomy, in particular for single-dish telescope observations. Due to both the increasing abundance of man-made interfering signals and the improved performance of the telescope instrumentation, the impact of RFI at the Italian radio telescope sites is now a major concern, thus strategies for its mitigation are to be applied. Dish Washer is a new software tool for the detection and flagging of RFI in signals collected by single-dish radio telescopes. It implements both interactive flagging and some level of automatic detection of RFI through dedicated algorithms. Its first public release is foreseen as free software under the GNU General Public License

FPGA-based digital back-ends for the Sardinia Radio Telescope

The Sardinia Radio Telescope (SRT), located in San Basilio, about 35 km north of Cagliari, is the largest (64-m diameter) radio telescope in Italy. It is a general-purpose, fully-steerable radio telescope designed to operate in the 300 MHz - 116 GHz frequency range, which allows it to perform a wide variety of scientific studies. The advanced electronic digital platforms that are installed at SRT play a key role, in particular those based on FPGAs (Field Programmable Gate Array), both because of their processing capability and their reconfigurability. In this paper, we present an overview of the digital back-ends available at SRT, as well as the ones under development; it is important to underline that, for all of them, FPGAs are the beating heart

Towards coordinated site monitoring and common strategies for mitigation of Radio Frequency Interference at the Italian radio telescopes

We present a project to implement a national common strategy for the mitigation of the steadily deteriorating Radio Frequency Interference (RFI) situation at the Italian radio telescopes. The project involves the Medicina, Noto, and Sardinia dish antennas and comprised the definition of a coordinated plan for site monitoring as well as the implementation of state-of-the-art hardware and software tools for RFI mitigation. Coordinated monitoring of frequency bands up to 40 GHz has been performed by means of continuous observations and dedicated measurement campaigns with fixed stations and mobile laboratories. Measurements were executed on the frequency bands allocated to the radio astronomy and space research service for shared or exclusive use and on the wider ones employed by the current and under-development receivers at the telescopes. Results of the monitoring campaigns provide a reference scenario useful to evaluate the evolution of the interference situation at the telescopes sites and a case series to test and improve the hardware and software tools we conceived to counteract radio frequency interference. We developed a multi-purpose digital backend for high spectral and time resolution observations over large bandwidths. Observational results demonstrate that the spectrometer robustness and sensitivity enable the efficient detection and analysis of interfering signals in radio astronomical data. A prototype off-line software tool for interference detection and flagging has been also implemented. This package is capable to handle the huge amount of data delivered by the most modern instrumentation on board of the Italian radio telecsopes, like dense focal plane arrays, and its modularity easen the integration of new algorithms and the re-usability in different contexts or telescopes.Comment: 39 pages, 10 Figures and 7 Tables. INAF Technical Report n. 149 (2022). http://hdl.handle.net/20.500.12386/3208

S-band Polarization All-Sky Survey (S-PASS): survey description and maps

We present the S-Band Polarization All Sky Survey (S-PASS), a survey of polarized radio emission over the southern sky at Dec. <−1◦ taken with the Parkes radio telescope at 2.3 GHz. The main aim was to observe at a frequency high enough to avoid strong depolarization at intermediate Galactic latitudes (still present at 1.4 GHz) to study Galactic magnetism, but low enough to retain ample signal-to-noise ratio (S/N) at high latitudes for extragalactic and cosmological science. We developed a new scanning strategy based on long azimuth scans and a corresponding map-making procedure to make recovery of the overall mean signal of Stokes Q and U possible, a long-standing problem with polarization observations. We describe the scanning strategy, map-making procedure and validation tests. The overall mean signal is recovered with a precision better than 0.5 per cent. The maps have a mean sensitivity of 0.81 mK on beam-size scales and show clear polarized signals, typically to within a few degrees of the Galactic plane, with ample S/N everywhere (the typical signal in low-emission regions is 13 mK and 98.6 per cent of pixels have S/N > 3). The largest depolarization areas are in the inner Galaxy, associated with the Sagittarius Arm. We have also computed a rotation measure map combining S-PASS with archival data from the Wilkinson Microwave Anisotropy Probe (WMAP) and Planck experiments. A Stokes I map has been generated, with sensitivity limited to the confusion level of 9 mK.RMC was the recipient of an Australian Research Council Future Fellowship (FT110100108). BMG acknowledges the support of the Natural Sciences and Engineering Research Council of Canada (NSERC) through grant RGPIN-2015-05948, and of the Canada Research Chairs program. XHS is supported by the National Natural Science Foundation of China under grant no. 11763008. MH acknowledges funding from the European Research Council (ERC) under the European Union Horizon 2020 research and innovation programme (grant agreement No 77266

Solar radiation effects on the Sardinia Radio Telescope performances

The Sardinia Radio Telescope, a 64-metre diameter fully steerable radio telescope operated by INAF, will be upgraded in order to extend its current operating frequency range 0.3-26.5 GHz up to 116 GHz, thanks to a National Operational Program (PON) funding assigned to INAF by the Italian Ministry of University and Research. The PON project is organized in nine Work Packages, one of which is dedicated to the accomplishment of a sophisticated metrology system designed to monitor the cause of the pointing errors and the reflector surface deformations. The entire antenna structure will therefore be equipped with a network of sensors, like thermal sensors, inclinometers, accelerometers, collimators, anemometers, strain gauges and others, to study environmental stresses and how they affect the SRT performances. This work is devoted to the investigation of the thermal stress effects produced by solar radiation. In particular, two analyses are carried out to confirm the relevance of a thorough temperature monitoring system, both conducted using Finite Element Analysis. First, a possible approach for the simulation of realistic thermal scenarios due to insolation is proposed and the effects on the pointing accuracy are analysed. Second, a feasible method to study the impacts that a differential heating of the Back Up Structure (BUS) produces on the radio telescope main reflector surface is presented. Finally, these effects are analysed as optical aberrations and modelled in terms of Zernike polynomials

Be social, be agile: team engagement with Redmine

System engineering and project-team management are essential tools to ensure the project success and the Redmine is a valuable platform for the work organization and for a system engineered approach. We review in this work the management needs related to our project, and suggest the possibility that they fit to many research activities with a similar scenario: small team, technical difficulties (or unknowns), intense activity sprints and long pauses due to external schedule management, a large degree of shared leadership. We will then present our implementation with the Redmine, showing that the use of the platform resulted in a strong engagement and commitment of the team. The explicit goal of this work is also to rise, at least internally, the awareness about team needs and available organizational tools and methods; and to highlight a shareable approach to team management and small scale system engineering