The 35th annual conference on Astronomical Data Analysis Software & Systems 2025 in Görlitz, Germany

The Monitor of All-sky X-ray Image (MAXI), installed on the Exposed Facility of the Japanese Experiment Module "Kibo" on the International Space Station (ISS) in 2009, has been providing valuable data for X-ray astronomy until now. The Data ARchives and Transmission System (DARTS: https://darts.isas.jaxa.jp), operated by JAXA, makes MAXI event data publicly available, enabling researchers to perform their own analysis. In this study, we develop a system that automatically generates and updates light curves of major targets.
MAXI data are downlinked via the ISS to the ground. Since the ISS maintains communication with the ground for about 70% of each day, data are obtained at relatively high frequency compared with other satellites. The remaining 30% of the observations are stored onboard and transmitted later, with delays ranging from several minutes to a few days. These delayed data must be inserted into the correct chronological order during the data processing. Furthermore, such updates need to be applied to all sources observed by MAXI whenever new data become available.
Currently, there are systems that generate light curves at fixed time intervals, but no system has been available that updates light curves upon each data delivery. Our system performs updates at every data downlink, incorporating the delayed data into the correct time sequence. As a result, it can provide the most up-to-date and high-quality light curves in the shortest possible time after data acquisition. This system facilitates the use of MAXI data and contributes to rapid scientific studies and the monitoring of variable X-ray sources.