Marco Bartolini

Water masers in the Kronian system

The presence of water has been considered for a long time as a key condition for life in planetary environments. The Cassini mission discovered water vapour in the Kronian system by detecting absorption of UV emission from a background star (Hansen et al. 2006). Prompted by this discovery, we started an observational campaign for search of another manifestation of the water vapour in the Kronian system, its maser emission at the frequency of 22 GHz (1.35 cm wavelength). Observations with the 32 m Medicina radio telescope (INAF-IRA, Italy) started in 2006 using Mk5A data recording and the JIVE-Huygens software correlator. Later on, an on-line spectrometer was used at Medicina. The 14 m Metsahovi radio telescope (TKK-MRO, Finland) joined the observational campaign in 2008 using a locally developed data capture unit and software spectrometer. More than 300 hours of observations were collected in 2006-2008 campaign with the two radio telescopes. The data were analysed at JIVE using the Doppler tracking technique to compensate the observed spectra for the radial Doppler shift for various bodies in the Kronian system (Pogrebenko et al. 2009). Here we report the observational results for Hyperion, Titan, Enceladus and Atlas, and their physical interpretation. Encouraged by these results we started a campaign of follow up observations including other radio telescopes.

An RFI mitigation project at the Italian radio telescopes

In this paper we present the first results of a project aiming at the mitigation of one of the most pressing problems for observational radio astronomy in Italy and the cm-wavelength telescopes world-wide: the ever-deteriorating situation of Radio Frequency Interference (RFI). We illustrate the campaigns conducted at the Noto 32m radio telescope and the Sardinia Radio Telescope (SRT) observing sites to monitor the evolution of RFI at these locations in the frequency range 0.05–40 GHz. A new FPGA-based spectrometer and an offline software tool for RFI detection and excision are presented and their performances are summarized.

The Sardinia Radio Telescope (SRT): A large modern radio telescope for observations from meter to mm wavelengths

The Sardinia Radio Telescope (SRT) is a new 64-m across radio astronomical facility located in Sardinia, Italy, and operated by the National Institute for Astrophysics (INAF). It can operate on a broad frequency range −300 MHz to 115 GHz, and is equipped with three different focus solutions: a primary, a Gregorian, and four Beam Wave Guide foci. The primary mirror is an active surface able to compensate the gravitational stress variations at different elevations and keeps the antenna gain flat and optimal at any elevation, as proven by regular observations of the 20-GHz system of the telescope. The optics is shaped and designed to minimise bandpass ripples that can jeopardise deep spectroscopic observations. Tests have delivered stunning results making SRT a world-class instrument for spectro-scopic astrophysical research. Currently, the receiver fleet comprises a P-L-band co-axial receiver (300–410 MHz and 1300–1800 MHz), a C–band system (5.7–7.7 GHz), and a K-band 7-beam array (18–26 GHz). A second C-band receiver (4.2–5.6 GHz), a 7-beam S-band array (3.0–4.5 GHz) and a 19-beam Q-band array (33–50 GHz) are being developed. The P-L-band package has an ultra-broad frequency coverage and its extension to 300 MHz at the low frequency end makes it a unique pulsar research machine in the current international radio astronomical context. The telescope has officially commenced its single-dish operations on 1 February 2016 with the start of an Early Science Program (ESP) that has been delivering stunning results. In this talk we will present the telescope, its main features that make it a unique radio astronomical instrument for several types of astrophysical observations, and results from its ESP campaign.

Rules of thumb to increase the software quality through testing

The software maintenance typically requires 40-80% of the overall project costs, and this considerable variability mostly depends on the software internal quality: the more the software is designed and implemented to constantly welcome new changes, the lower will be the maintenance costs. The internal quality is typically enforced through testing, which in turn also affects the development and maintenance costs. This is the reason why testing methodologies have become a major concern for any company that builds - or is involved in building - software. Although there is no testing approach that suits all contexts, we infer some general guidelines learned during the Development of the Italian Single-dish COntrol System (DISCOS), which is a project aimed at producing the control software for the three INAF radio telescopes (the Medicina and Noto dishes, and the newly-built SRT). These guidelines concern both the development and the maintenance phases, and their ultimate goal is to maximize the DISCOS software quality through a Behavior-Driven Development (BDD) workflow beside a continuous delivery pipeline. We consider different topics and patterns; they involve the proper apportion of the tests (from end-to-end to low-level tests), the choice between hardware simulators and mockers, why and how to apply TDD and the dependency injection to increase the test coverage, the emerging technologies available for test isolation, bug fixing, how to protect the system from the external resources changes (firmware updating, hardware substitution, etc.) and, eventually, how to accomplish BDD starting from functional tests and going through integration and unit tests. We discuss pros and cons of each solution and point out the motivations of our choices either as a general rule or narrowed in the context of the DISCOS project.

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.