## 1 Introduction  
Lightning discharges emit electromagnetic radiation in broadband frequency ranges covering from ULF/VLF, VHF/UHF, and even up to gamma-ray [1], where VHF energy can be detected and recorded by satellites through the ionosphere [2]. At the end of the 20 th century, the United States and a few European nations proposed an innovative concept of establishing a multi-star joint network to capture the electromagnetic pulses (EMPs) generated by lightning, thereby creating a global lightning location network. This network would complement the existing ground-based location networks and enhance the predictive capabilities for extreme weather events [3; 4]. Recently, the Marshall Space Flight Center of NASA and the Los Alamos Laboratory jointly launched the 'CubeSpark' project. This project plans to deploy six low-orbit small satellites equipped with optical and electromagnetic detectors to form a detection constellation, which will synchronously capture lightning EMPs to provide a detailed description of the three-dimensional morphology and evolution of lightning within thunderstorm clouds [5]. Although the detailed results of this technology have not yet been publicly reported and are still in the experimental stage, some low-orbit single satellite detection projects have made progress, such as the American ALEX satellite [2] and FORTE satellite [6], Russia's Chibis-M satellite [7], and Japan's Maido-1 satellite [8]. As for the characteristics and capabilities of high-orbit satellites in detecting lightning EMPs, recent studies have reported on the STPsat6 satellite [9]. The SY15 satellite was successfully deployed into a sun-synchronous orbit in September 2022. It operates with an orbital period of 90 min, revisits the same area every 11 h, and maintains an altitude of 500 km with an inclination of 97.5\({}^{\circ}\). The satellite is equipped with a wideband electromagnetic pulse detector (WEMPD) that is sensitive to a frequency band of 25 to 75 MHz, designed to detect atmospheric EMPs [10]. During its operational period from March 2023 to December 2023, the SY15 satellite captured some strong EMPs. To clarify, these events are identified when, after accounting for the ionospheric dispersion of the signal (a process known as 'declirping'), the square of the peak value of the electric field exceeds 0.1 mV\({}^{2}\)/m\({}^{2}\). This level of intensity corresponds to an effective radiated power from the ground source in the range of 10 kW. Additionally, the slant total electron content (STEC) inferred from the dechirping signal is found to be greater than 5 TECU (10\({}^{16}\) electrons/m\({}^{2}\)). The two defining characteristics of a strong EMP are mathematically expressed as \(E_{dec}^{2}>0.1\)mV\({}^{2}\)/m\({}^{2}\) and \(STEC_{dec}>5\)TECU. During the detection and recording of events, the satellite's subsatellite points are distributed globally. This necessitates the determination of the geographical locations of radiation sources to further investigate the origins of various types of events, as well as their seasonal variations and geographical distributions. Single-satellite detection of EMPs is not capable of directly pinpointing the source of radiation. The geographical locations of events detected by a single satellite are primarily ascertained by 'borrowing' the location information of concurrent events within the ground-based lightning location network [11; 12]. This method is named synchronous locating (SCL). However, there is often an issue with the inconsistent detection of frequency bands between the satellite-borne and ground-based systems that cover a broad area, as well as the focus on different physical processes of lightning. The satellite-borne system can detect more intra-cloud lightning flashes by monitoring the VHF band, while the ground-based system can detect more cloud-to-ground lightning flashes by monitoring the VLF band. This discrepancy leads to a very limited number of events that can be determined using the SCL method.