What is LWA?

The Long Wavelength Array (LWA) is a large-scale radio telescope system designed for observing the universe in the low-frequency range, It is primarily used for studying astronomical phenomena such as solar activity, cosmic radiation, pulsars, and the early universe. The LWA consists of a network of ground-based, crossed-dipole antennas arranged in an interferometric array that captures long-wavelength radio emissions from space.  This technology is crucial for studying celestial events that are difficult to observe at higher frequencies due to atmospheric or cosmic noise interference. The design of LWA makes it well-suited for collecting data on phenomena such as solar storms, space weather, and transient astronomical events. In addition to its primary astronomical applications, the LWA is also used for ionospheric research and monitoring space weather, making it a versatile tool for both scientific research and practical applications.

Scientific Application: Observing Frequency Range, and How LWA is Related to SunRISE

The LWA operates in the low-frequency radio spectrum, observing signals between 5 MHz and 85 MHz. This frequency range is critical for detecting solar emissions, space weather events, and low-frequency radiation from distant astronomical objects. The LWA is especially valuable for studying solar activity, including solar flares and coronal mass ejections (CMEs), which can affect space weather and satellite communications. One significant collaboration is between the LWA and the SunRISE (Sun Radio Interferometer Space Experiment) mission, which aims to observe solar radio bursts using an array of CubeSats in space. The LWA complements SunRISE by providing ground-based data on solar activity. This collaboration helps to create a more complete picture of solar phenomena, combining data from space and ground observatories. By studying solar emissions at these frequencies, it is possible to improve predictions of solar storms and gain a better understanding of the mechanisms behind these powerful events. In addition to studying solar phenomena, the LWA is also valuable for ionospheric studies. The Earth’s ionosphere affects the propagation of radio waves, especially in the low-frequency range. The ionosphere generally blocks space radiations below 15 MHz, except in rare conditions when solar activity influences this cutoff frequency ​(Reeve_LWA-Model). By examining the interaction of radio waves with the ionosphere, the LWA enhances understanding of its behavior, particularly during solar events, which improves space weather predictions and their impact on Earth’s atmosphere.

                                        LWA Spectrum

LWA System Components: Brief about Design and Structure

Hardware components: The LWA system features several critical hardware components, with the crossed-dipole antenna being the most prominent. This antenna consists of four elements arranged in an inverted V-shape, each acting as a dipole for capturing radio signals. This configuration allows the system to receive dual polarizations, enabling it to distinguish between right-hand and left-hand circular polarizations. These dipoles are connected to the front-end electronics (FEE), which function as an active balun, converting balanced dipole signals into unbalanced signals for transmission via coaxial cables. The FEE enhances signal strength and quality, providing 34 dB of gain with a noise figure of 2.7 dB. The antenna is supported by a central steel mast and grounded using a 3×3 meter galvanized mesh ground screen, which reduces ground reflection effects, stabilizes the environment, and improves signal reception. Additional hardware components include power couplers and bias-tees, which supply power to the FEE, and optional ground stakes that stabilize the system on various terrains. The modular design of the LWA makes assembly in the field straightforward and adaptable for diverse deployment conditions.

                                 Crossed Dipole Antenna

                                       E-Callisto System

Software components: We are currently employing a Mini Windows PC to facilitate the automated upload of data collected by the E-Callisto system, a radio spectrometer used to monitor solar activity. The system is set up to upload the collected data to Google Drive at 15-minute intervals, ensuring continuous data synchronization and storage in a cloud environment for easy access and analysis. Simultaneously, we are developing a comprehensive data pipeline that integrates machine learning algorithms to automatically classify the types of solar bursts captured by the E-Callisto system. This pipeline is designed to improve the efficiency of data processing by categorizing burst types with a high degree of accuracy, enabling quicker identification of significant solar events and contributing to more effective research and monitoring efforts in solar radio astronomy.

Observing Sites

We have two sites for the Sunrise project. One site is located at Peach Mountain, Michigan, with coordinates 42.403° latitude and -83.924° longitude. The second site is in Michigan’s Upper Peninsula, where we plan to set up an antenna for data collection due to the lower noise levels in that area.