Search

Probing the solar corona is crucial to study the coronal heating and solar wind acceleration. However, the transient and inhomogeneous solar wind flows carry large-amplitude inherent Alfven waves and turbulence, which make detection more difficult. We report the oscillation and propagation of the solar wind at 2.6 solar radii (Rs) by observation of China Tianwen and ESA Mars Express with radio telescopes. The observations were carried out on Oct.9 2021, when one coronal mass ejection (CME) passed across the ray paths of the telescope beams. We obtain the frequency fluctuations (FF) of the spacecraft signals from each individual telescope. Firstly, we visually identify the drift of the frequency spikes at a high spatial resolution of thousands of kilometers along the projected baselines. They are used as traces to estimate the solar wind velocity. Then we perform the cross-correlation analysis on the time series of FF from different telescopes. The velocity variations of solar wind structure along radial and tangential directions during the CME passage are obtained. The oscillation of tangential velocity confirms the detection of streamer wave. Moreover, at the tail of the CME, we detect the propagation of an accelerating fast field-aligned density structure indicating the presence of magnetohydrodynamic waves. This study confirm that the ground station-pairs are able to form particular spatial projection baselines with high resolution and sensitivity to study the detailed propagation of the nascent dynamic solar wind structure., 13 pages, 9 figures

We describe the design and architecture of PHAROS2, a cryogenically cooled 4-8 GHz Phased Array Feed (PAF) demonstrator with a digital beamformer for radio astronomy application. The instrument will be capable of synthesizing four independent single-polarization beams by combining 24 active elements of an array of Vivaldi antennas. PHAROS2, the upgrade of PHAROS (PHased Arrays for Reflector Observing Systems), features: a) commercial cryogenic LNAs with state-of-the-art performance, b) a “Warm Section” for signal filtering, conditioning and single downconversion to select a ≈275 MHz Intermediate Frequency (IF) bandwidth within the 4-8 GHz Radio Frequency (RF) band, c) an IF signal transportation by analog WDM (Wavelength Division Mutiplexing) fiber-optic link, and d) a FPGA-based Italian Tile Processing Module (iTPM) digital backend.

The aim of this article is to present the architecture proposed for the bistatic radar BIRALES (BIstatic Radar for LEo Surveys) as an instrument for space debris detection in the framework of the European Space Surveillance and Tracking Support Framework (EUSST). In the following paragraphs, the architecture and the upgrades done so far will be presented, as well as the multibeam technology and system calibration. Eventually, the orbit determination algorithm both for known and unknown objects is described, along with the numerical simulation.

We describe the design and performance of the Front- Ends for the 64-m diameter Sardinia Radio Telescope (SRT). An early science program was completed with SRT in August 2016, following a successful technical and scientific commissioning of the telescope and of its instrumentation. We give an overview of the three cryogenic Front-Ends, covering four bands, that were deployed on SRT during the early science program: P-band (305-410 MHz), L-band (1.3-1.8 GHz), high C-band (5.7- 7.7 GHz) and K-band (18-26.5 GHz). In addition, we describe the cryogenic Front-Ends that are currently under development, among which a seven beam for S-band (3.0-4.5 GHz) a mono-feed for Low-Cband (4.2-5.6 GHz), a 19-element for Q-band (33-50 GHz) and a mono-feed for a 3 mm band. Finally, we describe the development status of a demonstrator of a cryogenic C-band Phased Array Feed (PAF) for potential use at the SRT primary focus.

In the period 2012 June-2013 October, the Sardinia Radio Telescope (SRT) went through the technical commissioning phase. The characterization involved three first-light receivers, ranging in frequency between 300MHz and 26GHz, connected to a Total Power back-end. It also tested and employed the telescope active surface installed in the main reflector of the antenna. The instrument status and performance proved to be in good agreement with the expectations in terms of surface panels alignment (at present 300μmrms to be improved with microwave holography), gain (̃0.6K/Jy in the given frequency range), pointing accuracy (5 arcsec at 22GHz) and overall single-dish operational capabilities. Unresolved issues include the commissioning of the receiver centered at 350MHz, which was compromised by several radio frequency interferences, and a lower-than-expected aperture efficiency for the 22-GHz receiver when pointing at low elevations. Nevertheless, the SRT, at present completing its Astronomical Validation phase, is positively approaching its opening to the scientific community.