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Monitoring Solar Radio Bursts Using TART (Transient Array Radio Telescope) Radio Power at L-band Frequencies

written by Brian Mutula and Mary Dusabe

Introduction

The Transient Array Radio Telescope (TART) is a compact radio telescope designed for monitoring radio signals from satellites and space phenomena such as solar activity. Towards the end of August 2024, the Kenya Space Agency (KSA) partnered with the TART development team from New Zealand, through the Electronics Research Foundation, to install TART at the Technical University of Kenya (TUK) in Nairobi (Latitude: –1.292°, Longitude: 36.826°, Altitude: 751 m). The location near the equator is ideal because it provides a wide and balanced view of both the northern and southern skies, making it well-suited for continuous space monitoring.

TART consists of 24 antennas working together to observe radio signals. It operates at a frequency of 1.575 GHz, which falls in the L-band of the radio spectrum—commonly used for GNSS (Global Navigation Satellite Systems). The telescope has a 2.5 MHz bandwidth and a baseband frequency of 4.092 MHz, meaning it processes a narrow yet precise range of signals. Its sampling rate of 16.368 MHz enables high-resolution data capture, allowing scientists to detect rapid changes in radio emissions. The system operates in visibility mode (vis), where the data collected measures the combined signal strength and phase differences between antenna pairs, essential for analyzing sources of radio emissions in the sky.

Monitoring solar radio bursts
Solar radio bursts (SRBs) are powerful bursts of radio energy released by the Sun during solar flares and coronal mass ejections (CMEs). These events send high-energy particles and intense radio waves into space. When they enter our upper atmosphere, they can interfere with satellite communications, disrupt radio broadcasts, and degrade the accuracy of GNSS-based navigation systems like GPS. Data from TART’s 24 antennas was analyzed to measure changes in radio power received from the sky. The system combines signals from every pair of antennas (called baselines), and by summing these signals, the total radio power at each moment in time is determined.

Throughout the month of July 2025, several periods were observed where the measured radio power increased significantly for 5 to 20 minutes. Comparison with official solar flare reports from GOES X-ray data showed that many of these power spikes occurred at the same time as solar flares. This suggests that the observed radio power enhancements were caused by solar radio bursts (SRBs) rather than random noise or local interference. For example, on 24 July 2025, analysis show multiple spikes which coincided with C1 to C3 solar flare reports from https://www.spaceweatherlive.com/.

Figure 1: Time series of TART radio power (red) and Sun altitude (blue) on 24 July 2025, showing multiple power enhancements correlated with solar activity. The time is expressed in UTC

Analysis of the baseline-level power distribution using a heatmap was done to further investigate the nature of the detected power spikes. Figure 2 shows a zoomed-in section during a major burst event. The widespread increase across nearly all baselines demonstrates that the event affected the entire array simultaneously, consistent with a solar-origin radio burst. This is in contrast to localized noise sources, which typically only disturb a limited subset of baselines.

Figure 2: Zoomed-in heatmap of baseline power during a major spike on 24 July 2025, illustrating that all baselines were affected simultaneously, characteristic of a solar radio burst. In comparison, localized terrestrial noise typically impacts only a few baselines. Time is expressed in UTC.

Conclusion

Detecting solar radio bursts at 1.575 GHz shows that solar activity can cause measurable disturbances in frequencies used by satellite navigation systems. Monitoring these effects is vital for protecting technologies that rely on GNSS signals, including communication networks, navigation systems, and power grids. The Kenya Space Agency (KSA) has been expanding its efforts in space weather monitoring to safeguard technologies that rely on satellite communication and navigation. TART complements current monitoring tools by providing additional insights into solar activity. This added capacity enhances early-warning efforts and supports the development of strategies to forecast and mitigate disruptions caused by solar events on critical infrastructure.

Monitoring Solar Radio Bursts Using TART (Transient Array Radio Telescope) Radio Power at L-band Frequencies

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