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In this paper we present details of the construction of a wideband, cryogenic receiver and its successful commissioning on the Arecibo 12m telescope. The cryogenic receiver works in the 2.5-14 GHz frequency range. The telescope is operated by the Arecibo Observatory, and is located within the premises of the Observatory. We upgraded the current narrow band, room temperature receivers of the telescope with the new wideband receiver. The current receiver is built around a Quadruple-Ridged Flared Horn (QRHF) developed by Akgiray et al. (2013). To mitigate strong radio frequency interference (RFI) below 2.7 GHz, we installed a highpass filter before the first stage low noise amplifier (LNA). The QRHF, highpass filter, noise coupler and LNA are located inside a cryostat and are cooled to 15 K. The measured receiver temperature is 25 K (median value) over 2.5 GHz to 14 GHz. The system temperature measured at zenith is about 40 K near 3.1 and 8.6 GHz and the zenith antenna gains are 0.025 and 0.018 K/Jy at the two frequencies respectively. In the next stage of the development, we plan to upgrade the highpass filter in order to achieve better RFI rejection near 2.5 GHz, improve the aperture efficiency at 8.6 GHz and upgrade the IF system to increase the upper frequency of operation from 12 GHz to 14 GHz., Comment: 13 pages, 7 figures, 1 table (submitted for publication)

The Next Generation Arecibo Telescope (NGAT) was a concept presented in a white paper Roshi et al. (2021) developed by members of the Arecibo staff and user community immediately after the collapse of the 305 m legacy telescope. A phased array of small parabolic antennas placed on a tiltable plate-like structure forms the basis of the NGAT concept. The phased array would function both as a transmitter and as a receiver. This envisioned state of the art instrument would offer capabilities for three research fields, viz. radio astronomy, planetary and space & atmospheric sciences. The proposed structure could be a single plate or a set of closely spaced segments, and in either case it would have an equivalent collecting area of a parabolic dish of size 300 m. In this study we investigate the feasibility of realizing the structure. Our analysis shows that, although a single structure ~300 m in size is achievable, a scientifically competitive instrument 130 to 175 m in size can be developed in a more cost effective manner. We then present an antenna configuration consisting of one hundred and two 13 m diameter dishes. The diameter of an equivalent collecting area single dish would be ~130 m, and the size of the structure would be ~146 m. The weight of the structure is estimated to be 4300 tons which would be 53% of the weight of the Green Bank Telescope. We refer to this configuration as NGAT-130. We present the performance of the NGAT-130 and show that it surpasses all other radar and single dish facilities. Finally, we briefly discuss its competitiveness for radio astronomy, planetary and space & atmospheric science applications., Comment: 6 pages, 5 figures, 1 table, Invited paper for the ICEAA-IEEE APWC conference, Venice, Italy, Oct 9-13, 2023

The sudden release of magnetic energy on the Sun drives powerful solar flares and coronal mass ejections. The key issue is the difficulty in predicting the occurrence time and location of strong solar eruptions, i.e., those leading to the high impact space weather disturbances at the near-Earth environment. Solar radio imaging helps identify the magnetic field characteristics of active regions susceptible to intense flares and energetic coronal mass ejections. Mapping of the Sun at X-band (8.1 -- 9.3 GHz) with the 12-m radio telescope at the Arecibo Observatory allows monitoring of the evolution of the brightness temperature of active regions in association with the development of magnetic complexity, which can lead to strong eruptions. For a better forecasting strategy in the future, such ground-based radio observations of high-spatial and temporal resolution, along with a full polarization capability, would have tremendous potential not only to understand the magnetic activity of solar eruptions, but also for revealing the particle acceleration mechanism and additional exciting science., Comment: 11 pages and 3 figures (White Paper Submitted to `Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033')