The In-Flight Realtime Trigger and Localization Software of GECAM

Zhao, Xia; Xiong, S. L.; Wen, Xiang-Yang; Li, Xinqiao; Cai, C.; Xiao, Shuo; Luo, Qi; Peng, W. X.; Guo, D. Y.; An, Zhongfu; Gong, Ke; Liao, J. Y.; Zhang, Yanqiu; Huang, Yue; Li, Lü; Wen, Xiaoqing; Zhang, Fei; Duan, Jing; Wang, Chen-Wei; Shi, Dong-Li; Zhang, Peng; Yi, Q. B.; Li, Chaoyang; Xu, Yunlin; Liang, Xiaohua; Liu, Yaqing; Zhang, Dali; Sun, Xilei; Zhang, Fan; Chen, Gang; Wang, Huanyu; Yang, Shiwen; Liu, Xiaojing; Min, Gao; Li, Mao-Shun; Wang, Jin-Zhou; Zhang, Xing; Zhao, Yi; Xue, W. C.; Chen, Kewei; Liu, Jia-Cong; Han, Xiaopeng; Qi, Jin-Ling; Jia, Hongyan; Zhang, Ke-Ke; Chen, Can; Yang, Xiongtao; Hou, Dongjie; Wang, Yusa; Qiao, Rui; Ma, Xiang; Li, Xiaobo; Wang, Ping; Song, X. Y.; Song, Liming; Zheng, S.; Li, Bing; Zhang, Hongmei; Zhu, Yanyan; Chen, Wei; He, J.; Zhang, Zhen; Hou, Jing; Wang, Hongjun; Hao, Yan-Chao; Wang, Xiangyu; Yang, Zongyuan; Wen, Zhi-Long; Chang, Zhi; Du, Ying; Gao, Rui; Lan, Xiaofei; Li, Yanguo; Li, Gang; Li, Xu-Fang; Lü, H.; Meng, Bo; Shi, Feng; Wang, Hui; Wang, Huizhen; Xu, Yupeng; Yang, Jian; Yang, Xuejuan; Zhang, Shuang‐Nan; Zhang, Chaoyue; Zhang, Chengmo; Tang, Zhicheng; Cheng, Cheng

doi:10.48550/arxiv.2112.05101

Cited by 6 publications

(8 citation statements)

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“…By the end of 2022 May, hundreds of bursts had been detected by GECAM-B (Zhao et al 2021;C. Cai et al 2023, in preparation;Y.…”

Section: Grbs Sgrs and Sflsmentioning

confidence: 99%

“…With the LaBr 3 crystal read out by a silicon photomultiplier array, GRDs could monitor the entire unocculted sky in the energy range of ∼15 keV to ∼5 MeV (Zhang et al 2022b(Zhang et al , 2022d. The CPD is designed to detect charged particles in the orbit, which is powerful for observing terrestrial electron beams and helping the GRDs to distinguish between gamma-ray burst events and charged particle burst events (Zhao et al 2021).…”

Section: Introductionmentioning

confidence: 99%

“…As shown in Table 1, a series of localization algorithms have been developed by the GECAM team for different stages after the trigger of a burst (Liao et al 2020;Zhao et al 2021;C. Cai et al 2023, in preparation;Y.…”

Section: Introductionmentioning

confidence: 99%

“…1. For onboard triggered bursts, the flight software computes their locations and provides a preliminary classification of the bursts within ∼20 s (Zhao et al 2021). The flight software employs a χ 2 minimization localization method considering the very limited onboard resources of computing and storage.…”

Section: Introductionmentioning

confidence: 99%

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GECAM Localization of High-energy Transients and the Systematic Error

Zhao

Xue

Xiong³

et al. 2023

ApJS

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The Gravitational Wave High-energy Electromagnetic Counterpart All-sky Monitor (GECAM) is a pair of microsatellites (i.e., GECAM-A and GECAM-B) dedicated to monitoring gamma-ray transients including the high-energy electromagnetic counterparts of gravitational waves, such as gamma-ray bursts, soft gamma-ray repeaters, solar flares, and terrestrial gamma-ray flashes. Since launch in 2020 December, GECAM-B has detected hundreds of astronomical and terrestrial events. For these bursts, localization is the key for burst identification and classification as well as follow-up observations in multiple wavelengths. Here, we propose a Bayesian localization method with Poisson data with Gaussian background profile likelihood to localize GECAM bursts based on the distribution of burst counts in detectors with different orientations. We demonstrate that this method can work well for all kinds of bursts, especially extremely short ones. In addition, we propose a new method to estimate the systematic error of localization based on a confidence level test, which can overcome some problems of the existing method in the literature. We validate this method by Monte Carlo simulations, and then apply it to a burst sample with accurate location and find that the mean value of the systematic error of GECAM-B localization is ∼2.°5. By considering this systematic error, we can obtain a reliable localization probability map for GECAM bursts. Our methods can be applied to other gamma-ray monitors.

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“…By the end of 2022 May, hundreds of bursts had been detected by GECAM-B (Zhao et al 2021;C. Cai et al 2023, in preparation;Y.…”

Section: Grbs Sgrs and Sflsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

GECAM Localization of High-energy Transients and the Systematic Error

Zhao

Xue

Xiong³

et al. 2023

ApJS

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“…At the time of writing, real time triggers and 1σ localisations for short GRBs can be obtained with accuracies < 10's of square degrees (e.g., Fermi GBM (Goldstein et al, 2020), the Neil Gehrels Swift Observatory (Gehrels et al, 2004;Troja, 2020), the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM; Zhao et al (2021)). To localise a substantial fraction of short GRBs to this accuracy with the current design of the HERMES instrument (and under the assumption that the satellites are uniformly distributed around equatorial and Polar orbits), at least 20 satellites divided evenly between equatorial and Polar orbit all observing the same field are required (i.e., combined detection from at least 10 HERMES instruments with large baselines in both the equatorial and Polar planes).…”

Section: Short Grbsmentioning

confidence: 99%

Localisation of gamma-ray bursts from the combined SpIRIT+HERMES-TP/SP nano-satellite constellation

Thomas¹,

Trenti²,

Campana³

et al. 2023

Preprint

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Multi-messenger observations of the transient sky to detect cosmic explosions and counterparts of gravitational wave mergers critically rely on orbiting wide-FoV telescopes to cover the wide range of wavelengths where atmospheric absorption and emission limit the use of ground facilities. Thanks to continuing technological improvements, miniaturised space instruments operating as distributed-aperture constellations are offering new capabilities for the study of high energy transients to complement ageing existing satellites. In this paper we characterise the performance of the upcoming joint SpIRIT and HERMES-TP/SP constellation for the localisation of high-energy transients through triangulation of signal arrival times. SpIRIT is an Australian technology and science demonstrator satellite designed to operate in a low-Earth Sun-synchronous Polar orbit that will augment the science operations for the equatorial HERMES-TP/SP constellation. In this work we simulate the improvement to the localisation capabilities of the HERMES -TP/SP constellation when SpIRIT is included in an orbital plane nearly perpendicular (inclination = 97.6°) to the HERMES -TP/SP orbits. For the fraction of GRBs detected by three of the HERMES satellites plus SpIRIT, we find that the combined constellation is capable of localising 60% of long GRBs to within ∼ 30 deg 2 on the sky, and 60% of short GRBs within ∼ 1850 deg 2 (1σ confidence regions), though it is beyond the scope of this work to characterise or rule out systematic uncertainty of the same order of magnitude. Based purely on statistical GRB localisation capabilities (i.e., excluding systematic uncertainties and sky coverage), these figures for long GRBs are comparable to those reported by the Fermi Gamma Burst Monitor instrument. These localisation statistics represents a reduction of the uncertainty for the burst localisation region for both long and short GRBs by a factor of ∼ 5 compared to the HERMES-TP/SP alone. Further improvements by an additional factor of 2 (or 4) can be achieved by launching an additional 4 (or 6) SpIRIT-like satellites into a Polar orbit respectively, which would both increase the fraction of sky covered by multiple satellite elements, and also enable localisation of ≥ 60% of long GRBs to within a radius of ∼ 1.5°(statistical uncertainty) on the sky, clearly demonstrating the value of a distributed all-sky high energy transient monitor composed of nano-satellites.

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