STORMY : A Real-time Triggering Framework using Yamagawa Solar Spectrograph for Active Solar Emission Observations with the MWA

TL;DR

STORMY introduces a near-real-time triggering framework for solar observations with the MWA by leveraging data from the Yamagawa solar spectrograph to efficiently capture transient solar radio bursts. The authors implement an end-to-end pipeline including bandpass correction, RFI mitigation, adaptive background subtraction, and binary dynamic-spectrum based event detection, culminating in automated triggers that reconfigure the MWA for short, targeted interferometric observations. Performance is quantified via precision, recall, and F1 metrics, showing an optimum around a $13\sigma$ threshold and successful operation with ~110 bursts recorded between mid-2024 and early-2025. The framework is positioned to be applicable to other facilities (e.g., LOFAR, OVRO-LWA, SKA-Low), enabling efficient triggered solar observations and informing SKA-era solar studies.

Abstract

Some of the most interesting insights into solar physics and space weather come from studying radio emissions associated with solar activity, which remain inherently unpredictable. Hence, a real-time triggering system is needed for solar observations with the versatile new-generation radio telescopes to efficiently capture these episodes of solar activity with the precious and limited solar observing time. We have developed such a system, Solar Triggered Observations of Radio bursts using MWA and Yamagawa (STROMY) for the Murchison Widefield Array (MWA), the precursor for the low frequency telescope of upcoming Square Kilometre Array Observatory (SKAO). It is based on near-real-time data from the Yamagawa solar spectrograph, located at a similar longitude to the MWA. We have devised, implemented, and tested algorithms to perform an effective denoising of the data to identify signatures of solar activity in the Yamagawa data in near real-time. End-to-end tests of triggered observations have been successfully carried out at the MWA. STORMY is operational at the MWA for the routine solar observations, a timely development in the view of the ongoing solar maximum. We present this new observing framework and discuss how it can enable efficient capturing of event-rich solar data with existing instruments, like the LOw Frequency ARray (LOFAR), Owens Valley Radio Observatory - Long Wavelength Array (OVRO-LWA) etc., and pave the way for triggered observing with the SKAO, especially the SKA-Low.

Figures (12)

• Figure 1: This figure shows an example of the real-time update of data from Yamagawa spectrograph and the MWA voltage buffer. For example: the chunk a is available at 2:46 and the next chunk b is available at 2:48, as seen in the figure. When a trigger is sent, the buffer data (red block) is saved and a regular correlator observation (blue arrow) is triggered. We lose about 1-minute of data even after recovering 160s of data from the MWA buffer.
• Figure 2: A schematic block diagram providing an overview of the entire observation triggering pipeline.
• Figure 3: Raw Yamagawa data is shown on the left panel and the median bandpass calculated from previous full day data is shown in the right panel.
• Figure 4: This figure shows the bandpass normalised dynamic spectrum where the varying signals are easily detectable. The yellow rectangles show a periodic RFI that is seen every 300 seconds. The red arrows show narrow band persistent RFIs.
• Figure 5: This figure shows how the periodic RFI is cleaned. The top left panel shows the dynamic spectrum with fragmented periodic RFI. The top right panel shows the dynamic spectrum after cleaning these RFI. The part within the 2. The x-axes are shared across subplots in each column.