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Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) is a space-borne instrument dedicated to monitoring high-energy transients, thereinto Terrestrial Gamma-ray Flashes (TGFs) and Terrestrial Electron Beams (TEBs). We propose a TGF/TEB search algorithm, with which 147 bright TGFs and 4 TEBs are identified during an effective observation time of $\sim$ 9 months. We show that, with gamma-ray and charged particle detectors, GECAM can effectively identify and distinguish TGFs and TEBs, and measure their temporal and spectral properties in detail. Moreover, we find an interesting TEB consisting of two pulses with a separation of $\sim$ 150 ms, which is expected to originate from a lightning process near the geomagnetic footprint. We also find that the GECAM TGF’s lightning-association ratio is $\sim$ 80\% in the east Asia region using the GLD360 lightning network, which is significantly higher than previous observations.

Background The Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) is primarily designed to spot gamma-ray bursts corresponding to gravitational waves. In order to achieve stable observations from various astronomical phenomena, the payload performance need to be monitored during the in-orbit operation. Method This article describes the design and implementation of GECAM satellite payload performance monitoring (GPPM) software. The software extracts the payload status and telescope observations (light curves, energy spectrums, characteristic peak fitting of energy spectrums, etc) from the payload data. Considering the large amount of payload status parameters in the engineering data, we have designed a method of parameter processing based on the configuration tables. This method can deal with the frequent changes of the data formats and facilitate program maintenance. Payload status and performance are monitored through defined thresholds and monitoring reports. The entire software is implemented in python language and the huge amount of observation data is stored in MongoDB. Conclusion The design and implementation of GPPM software have been completed, tested with ground and in-orbit payload data. The software can monitor the performance of GECAM payload effectively. The overall design of the software and the data processing method can be applied to other satellites., Published in RDTM