Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Xu-Fang Li
Cong-Zhan Liu
Yi-Fei Zhang
Xiao-Bo Li
Zheng-Wei Li
Xue-Feng Lu
Zhi Chang
Ming-Yu Ge
Juan Zhang
Yu-Peng Xu
Fang-Jun Lu
Li-Ming Song
Shuang-Nan Zhang
Abstract： Purpose: The High-Energy X-ray telescope (HE), one of the three main payloads of the \textit{Insight}-HXMT mission, is composed of eighteen NaI(Tl)/CsI(Na) phoswich detectors, where NaI(Tl) serves as the primary detector covering 20--250\,keV, and CsI(Na) is used as an active shield detector to suppress the background of NaI(Tl) and also serves as an all-sky gamma-ray burst monitor covering 0.2--3\,MeV. In this paper, we review the in-orbit performance of HE in the first 5 years since \textit{Insight}-HXMT was launched on June 15, 2017. Methods: The major performances we concern include the gain and energy resolution of NaI(Tl) and CsI(Na) detectors, the performance of pulse-shape-discriminator (PSD) and system dead-time. In this work, we investigate these performances mainly using the data of blank-sky observations and the data when the telescope in earth occultation. Results: The overall performance of HE/NaI(Tl) is very stable in the first 5 years, whereas the gain of HE/CsI(Na) shows a continuously increasing trend and should be calibrated regularly. Conclusion: In general, HE is still in good health and well-calibrated status after five-year's operation. The in-orbit performance of HE has no significant deviation from expectation. HE is expected to be in operation healthily for another several years of extended mission life.
Peer Review Status:
Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Jin-Yuan Liao
Shu Zhang
Juan Zhang
Gang Li
Zhi Chang
Yu-Peng Chen
Ming-Yu Ge
Jing Jin
Xue-Feng Lu
Yuan You
Xue-Lei Cao
Yong Chen
Yue Huang
Wei-Chun Jiang
Xiao-Bo Li
Xu-Fang Li
Zheng-Wei Li
Cong-Zhan Liu
Ying Tan
Yan-Ji Yang
Abstract： Purpose: We present the five-year in-orbit background evolution of Insight-HXMT since the launch, as well as the effects of the background model in data analysis. Methods: The backgrounds of the three main payloads, i.e., Low-Energy Telescope, Medium-Energy Telescope and High-Energy Telescope, are described, respectively. The evolution of the background over time is obtained by simply comparing the background in every year during the in-orbit operation of Insight-HXMT. Results: The major observational characteristics of the Insight-HXMT in-orbit background are presented, including the light curve, spectrum, geographical distribution, and long-term evolution. The systematic error in background estimation is investigated for every year. Conclusion: The observational characteristics of the five-year in-orbit background are consistent with our knowledge of the satellite design and the space environment, and the background model is still valid for the latest observations of Insight-HXMT.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Jin-Yuan Liao
Shu Zhang
Juan Zhang
Gang Li
Zhi Chang
Yu-Peng Chen
Ming-Yu Ge
Jing Jin
Xue-Feng Lu
Yuan You
Xue-Lei Cao
Yong Chen
Yue Huang
Wei-Chun Jiang
Xiao-Bo Li
Xu-Fang Li
Zheng-Wei Li
Cong-Zhan Liu
Ying Tan
Yan-Ji Yang
Abstract： Purpose: We present the five-year in-orbit background evolution of Insight-HXMT since the launch, as well as the effects of the background model in data analysis. Methods: The backgrounds of the three main payloads, i.e., Low-Energy Telescope, Medium-Energy Telescope and High-Energy Telescope, are described, respectively. The evolution of the background over time is obtained by simply comparing the background in every year during the in-orbit operation of Insight-HXMT. Results: The major observational characteristics of the Insight-HXMT in-orbit background are presented, including the light curve, spectrum, geographical distribution, and long-term evolution. The systematic error in background estimation is investigated for every year. Conclusion: The observational characteristics of the five-year in-orbit background are consistent with our knowledge of the satellite design and the space environment, and the background model is still valid for the latest observations of Insight-HXMT.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Yan-Qiu Zhang
Shao-Lin Xiong
Rui Qiao
Dong-Ya Guo
Wen-Xi Peng
Xin-Qiao Li
Wang-Chen Xue
Chao Zheng
Jia-Cong Liu
Wen-Jun Tan
Chen-Wei Wang
Peng Zhang
Ping Wang
Ce Cai
Shuo Xiao
Yue Huang
Pei-Yi Feng
Xiao-Bo Li
Li-Ming Song
Qi-Bin Yi
Abstract： The gamma-ray detectors (GRDs) of GECAM-C onborad SATech-01 satellite is designed to monitor gamma-ray transients all over the sky from 6 keV to 6 MeV. The energy response matrix is the key to do spectral measurements of bursts, which is usually generated from GEANT4 simulation and partially verified by the ground calibration. In this work, energy response matrix of GECAM-C GRD is cross-calibrated with Fermi/GBM and Swift/BAT using a sample of Gamma-Ray Bursts (GRBs) and Soft Gamma-Ray Repeaters (SGRs). The calibration results show there is a good agreement between GECAM-C and other reasonably well calibrated instrument (i.e. Fermi/GBM and Swift/BAT). We also find that different GRD detectors of GECAM-C also show consistency with each other. All these results indicate that GECAM-C GRD can provide reliable spectral measurements.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Wang-Chen Xue
Xiao-Bo Li
Shao-Lin Xiong
Yong Chen
Shuang-Nan Zhang
Li-Ming Song
Shu Zhang
Ming-Yu Ge
You-Li Tuo
Hai-Tao Li
Dao-Chun Yu
Dong-Ya Guo
Jia-Cong Liu
Yan-Qiu Zhang
Chao Zheng
Abstract： The Earth occultation technique has broad applications in both astronomy and atmospheric density measurements. We construct the background model during the occultation of the Crab Nebula observed by the Insight-Hard X-ray Modulation Telescope (Insight-HXMT) at energies between 6 keV and 100 keV. We propose a Bayesian atmospheric density retrieval method based on the Earth occultation technique, combining Poisson and Gaussian statistics. By modeling the atmospheric attenuation of X-ray photons during the occultation, we simultaneously retrieved the neutral densities of the atmosphere at different altitude ranges. Our method considers the correlation of densities between neighboring atmospheric layers and reduces the potential systematic bias to which previous work may be subject. Previous analyses based on light curve fitting or spectral fitting also lost some spectral or temporal information of the data. In contrast to previous work, the occultation data observed by the three telescopes onboard Insight-HXMT is fully used in our analysis, further reducing the statistical error in density retrieval. We apply our method to cross-check the (semi-)empirical atmospheric models, using 115 sets of occultation data of the Crab Nebula observed by Insight-HXMT. We find that the retrieved neutral density is ~10%, ~20%, and ~25% less than the values of the widely used atmospheric model NRLMSISE-00, in the altitude range of 55--80 km, 80--90 km, and 90--100 km, respectively. We also show that the newly released atmospheric model NRLMSIS 2.0 is generally consistent with our density measurements.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Xu-Fang Li
Cong-Zhan Liu
Yi-Fei Zhang
Xiao-Bo Li
Zheng-Wei Li
Xue-Feng Lu
Zhi Chang
Ming-Yu Ge
Juan Zhang
Yu-Peng Xu
Fang-Jun Lu
Li-Ming Song
Shuang-Nan Zhang
Abstract： Purpose: The High-Energy X-ray telescope (HE), one of the three main payloads of the \textit{Insight}-HXMT mission, is composed of eighteen NaI(Tl)/CsI(Na) phoswich detectors, where NaI(Tl) serves as the primary detector covering 20--250\,keV, and CsI(Na) is used as an active shield detector to suppress the background of NaI(Tl) and also serves as an all-sky gamma-ray burst monitor covering 0.2--3\,MeV. In this paper, we review the in-orbit performance of HE in the first 5 years since \textit{Insight}-HXMT was launched on June 15, 2017. Methods: The major performances we concern include the gain and energy resolution of NaI(Tl) and CsI(Na) detectors, the performance of pulse-shape-discriminator (PSD) and system dead-time. In this work, we investigate these performances mainly using the data of blank-sky observations and the data when the telescope in earth occultation. Results: The overall performance of HE/NaI(Tl) is very stable in the first 5 years, whereas the gain of HE/CsI(Na) shows a continuously increasing trend and should be calibrated regularly. Conclusion: In general, HE is still in good health and well-calibrated status after five-year's operation. The in-orbit performance of HE has no significant deviation from expectation. HE is expected to be in operation healthily for another several years of extended mission life.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Yi Zhao
Wang-Chen Xue
Shao-Lin Xiong
Yuan-Hao Wang
Jia-Cong Liu
Qi Liuo
Yan-Qiu Zhang
Jian-Chao Sun
Xiao-Yun Zhao
Ce Cai
Shuo Xiao
Yue Huang
Xiao-Bo Li
Zhen Zhang
Jin-Yuan Liao
Sheng Yang
Rui Qiao
Dong-Ya Guo
Chao Zheng
Qi-Bin Yi
Abstract： 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 gravitational waves high-energy electromagnetic counterparts, Gamma-ray Bursts, Soft Gamma-ray Repeaters, Solar Flares and Terrestrial Gamma-ray Flashes. Since launch in December 2020, 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 multi-wavelength. Here, we propose a Bayesian localization method with Poisson data with Gaussian background profile likelihood to localize GECAM bursts based on the burst counts distribution in detectors with different orientations. We demonstrate that this method can work well for all kinds of bursts, especially for 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 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 $\sim 2.5^{\circ}$. 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.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Yi Zhao
Wang-Chen Xue
Shao-Lin Xiong
Yuan-Hao Wang
Jia-Cong Liu
Qi Liuo
Yan-Qiu Zhang
Jian-Chao Sun
Xiao-Yun Zhao
Ce Cai
Shuo Xiao
Yue Huang
Xiao-Bo Li
Zhen Zhang
Jin-Yuan Liao
Sheng Yang
Rui Qiao
Dong-Ya Guo
Chao Zheng
Qi-Bin Yi
Abstract： 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 gravitational waves high-energy electromagnetic counterparts, Gamma-ray Bursts, Soft Gamma-ray Repeaters, Solar Flares and Terrestrial Gamma-ray Flashes. Since launch in December 2020, 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 multi-wavelength. Here, we propose a Bayesian localization method with Poisson data with Gaussian background profile likelihood to localize GECAM bursts based on the burst counts distribution in detectors with different orientations. We demonstrate that this method can work well for all kinds of bursts, especially for 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 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 $\sim 2.5^{\circ}$. 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.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Wang-Chen Xue
Xiao-Bo Li
Shao-Lin Xiong
Yong Chen
Shuang-Nan Zhang
Li-Ming Song
Shu Zhang
Ming-Yu Ge
You-Li Tuo
Hai-Tao Li
Dao-Chun Yu
Dong-Ya Guo
Jia-Cong Liu
Yan-Qiu Zhang
Chao Zheng
Abstract： The Earth occultation technique has broad applications in both astronomy and atmospheric density measurements. We construct the background model during the occultation of the Crab Nebula observed by the Insight-Hard X-ray Modulation Telescope (Insight-HXMT) at energies between 6 keV and 100 keV. We propose a Bayesian atmospheric density retrieval method based on the Earth occultation technique, combining Poisson and Gaussian statistics. By modeling the atmospheric attenuation of X-ray photons during the occultation, we simultaneously retrieved the neutral densities of the atmosphere at different altitude ranges. Our method considers the correlation of densities between neighboring atmospheric layers and reduces the potential systematic bias to which previous work may be subject. Previous analyses based on light curve fitting or spectral fitting also lost some spectral or temporal information of the data. In contrast to previous work, the occultation data observed by the three telescopes onboard Insight-HXMT is fully used in our analysis, further reducing the statistical error in density retrieval. We apply our method to cross-check the (semi-)empirical atmospheric models, using 115 sets of occultation data of the Crab Nebula observed by Insight-HXMT. We find that the retrieved neutral density is ~10%, ~20%, and ~25% less than the values of the widely used atmospheric model NRLMSISE-00, in the altitude range of 55--80 km, 80--90 km, and 90--100 km, respectively. We also show that the newly released atmospheric model NRLMSIS 2.0 is generally consistent with our density measurements.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Xiao-Yun Zhao
Shao-Lin Xiong
Xiang-Yang Wen
Xin-Qiao Li
Ce Cai
Shuo Xiao
Qi Luo
Wen-Xi Peng
Dong-Ya Guo
Zheng-Hua An
Ke Gong
Jin-Yuan Liao
Yan-Qiu Zhang
Yue Huang
Lu Li
Xing Wen
Fei Zhang
Jing Duan
Chen-Wei Wang
Dong-Li Shi
Abstract： Realtime trigger and localization of bursts are the key functions of GECAM, which is an all-sky gamma-ray monitor launched in Dec 10, 2020. We developed a multifunctional trigger and localization software operating on the CPU of the GECAM electronic box (EBOX). This onboard software has the following features: high trigger efficiency for real celestial bursts with a suppression of false triggers caused by charged particle bursts and background fluctuation, dedicated localization algorithm optimized for short and long bursts respetively, short time latency of the trigger information which is downlinked throught the BeiDou satellite navigation System (BDS). This paper presents the detailed design and deveopment of this trigger and localization software system of GECAM, including the main functions, general design, workflow and algorithms, as well as the verification and demonstration of this software, including the on-ground trigger tests with simulated gamma-ray bursts made by a dedicated X-ray tube and the in-flight performance to real gamma-ray bursts and magnetar bursts.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Yan-Qiu Zhang
Shao-Lin Xiong
Rui Qiao
Dong-Ya Guo
Wen-Xi Peng
Xin-Qiao Li
Wang-Chen Xue
Chao Zheng
Jia-Cong Liu
Wen-Jun Tan
Chen-Wei Wang
Peng Zhang
Ping Wang
Ce Cai
Shuo Xiao
Yue Huang
Pei-Yi Feng
Xiao-Bo Li
Li-Ming Song
Qi-Bin Yi
Abstract： The gamma-ray detectors (GRDs) of GECAM-C onborad SATech-01 satellite is designed to monitor gamma-ray transients all over the sky from 6 keV to 6 MeV. The energy response matrix is the key to do spectral measurements of bursts, which is usually generated from GEANT4 simulation and partially verified by the ground calibration. In this work, energy response matrix of GECAM-C GRD is cross-calibrated with Fermi/GBM and Swift/BAT using a sample of Gamma-Ray Bursts (GRBs) and Soft Gamma-Ray Repeaters (SGRs). The calibration results show there is a good agreement between GECAM-C and other reasonably well calibrated instrument (i.e. Fermi/GBM and Swift/BAT). We also find that different GRD detectors of GECAM-C also show consistency with each other. All these results indicate that GECAM-C GRD can provide reliable spectral measurements.
Peer Review Status:Awaiting Review
Hits
Hits
Downloads
Comment