Fast Radio Bursts(FRBs)have emerged as one of the most intriguing and enigmatic phenomena in the field of radio astronomy.The key of current related research is to obtain enough FRB signals.Computer-aided search is ne...Fast Radio Bursts(FRBs)have emerged as one of the most intriguing and enigmatic phenomena in the field of radio astronomy.The key of current related research is to obtain enough FRB signals.Computer-aided search is necessary for that task.Considering the scarcity of FRB signals and massive observation data,the main challenge is about searching speed,accuracy and recall.in this paper,we propose a new FRB search method based on Commensal Radio Astronomy FAST Survey(CRAFTS)data.The CRAFTS drift survey data provide extensive sky coverage and high sensitivity,which significantly enhance the probability of detecting transient signals like FRBs.The search process is separated into two stages on the knowledge of the FRB signal with the structural isomorphism,while a different deep learning model is adopted in each stage.To evaluate the proposed method,FRB signal data sets based on FAST observation data are developed combining simulation FRB signals and real FRB signals.Compared with the benchmark method,the proposed method F-score achieved 0.951,and the associated recall achieved 0.936.The method has been applied to search for FRB signals in raw FAST data.The code and data sets used in the paper are available at github.com/aoxipo.展开更多
The image quality of a large field survey telescope with a fast focal ratio of the primary mirror is high sensitivity to the optical elements’misalignments and the primary mirror’s deformations.To maintain good opti...The image quality of a large field survey telescope with a fast focal ratio of the primary mirror is high sensitivity to the optical elements’misalignments and the primary mirror’s deformations.To maintain good optical performance,the perturbations need to be aligned,and the tomographic reconstruction of these perturbations can be derived from wavefront sensing with multi-field points for alignment.This work undertakes a comprehensive examination related to the implementation and optimization of a multi-field split curvature wavefront sensing system,including defocus distance,signal pre-processing,deblending of overlapped doughnuts,field-dependent correction,and distorted coordinate correction.We also conduct experiments to demonstrate the application and performance of a multi-field split curvature wavefront sensing system in Mephisto.In the context of the decentering of the secondary mirror,the coefficient of determination(R)attains a high value of 0.993,indicating a robust linearity between the coma coefficients and the decentering of the secondary mirror.A comparative analysis of the simulated and experimental results shows that the difference between them is less than 0.1λ.展开更多
For the public having a better understanding of solar activities,the Educational Adaptive-optics Solar Telescope(EAST)was built in July 2021 and is located at the Shanghai Astronomy Museum.The EAST consists of a 65 cm...For the public having a better understanding of solar activities,the Educational Adaptive-optics Solar Telescope(EAST)was built in July 2021 and is located at the Shanghai Astronomy Museum.The EAST consists of a 65 cm aperture solar telescope with a 177-element adaptive optics system and two-channel high resolution imaging system at the Hαand TiO bands,in addition to three full disk solar telescopes at CaK,Hαand TiO bands equipped on the tube of the main telescope.In this paper,the configuration of the EAST is described.Its performance and on-sky observational results are presented.The EAST,to our knowledge,is the most advanced solar telescope for the popularization of science in the world.Due to its excellent performance,the data acquired by the EAST can also be used for research on solar physics and space weather prediction.展开更多
文摘Fast Radio Bursts(FRBs)have emerged as one of the most intriguing and enigmatic phenomena in the field of radio astronomy.The key of current related research is to obtain enough FRB signals.Computer-aided search is necessary for that task.Considering the scarcity of FRB signals and massive observation data,the main challenge is about searching speed,accuracy and recall.in this paper,we propose a new FRB search method based on Commensal Radio Astronomy FAST Survey(CRAFTS)data.The CRAFTS drift survey data provide extensive sky coverage and high sensitivity,which significantly enhance the probability of detecting transient signals like FRBs.The search process is separated into two stages on the knowledge of the FRB signal with the structural isomorphism,while a different deep learning model is adopted in each stage.To evaluate the proposed method,FRB signal data sets based on FAST observation data are developed combining simulation FRB signals and real FRB signals.Compared with the benchmark method,the proposed method F-score achieved 0.951,and the associated recall achieved 0.936.The method has been applied to search for FRB signals in raw FAST data.The code and data sets used in the paper are available at github.com/aoxipo.
基金supported by the National Natural Science Foundation of China(grant No.12173062)。
文摘The image quality of a large field survey telescope with a fast focal ratio of the primary mirror is high sensitivity to the optical elements’misalignments and the primary mirror’s deformations.To maintain good optical performance,the perturbations need to be aligned,and the tomographic reconstruction of these perturbations can be derived from wavefront sensing with multi-field points for alignment.This work undertakes a comprehensive examination related to the implementation and optimization of a multi-field split curvature wavefront sensing system,including defocus distance,signal pre-processing,deblending of overlapped doughnuts,field-dependent correction,and distorted coordinate correction.We also conduct experiments to demonstrate the application and performance of a multi-field split curvature wavefront sensing system in Mephisto.In the context of the decentering of the secondary mirror,the coefficient of determination(R)attains a high value of 0.993,indicating a robust linearity between the coma coefficients and the decentering of the secondary mirror.A comparative analysis of the simulated and experimental results shows that the difference between them is less than 0.1λ.
基金supported by the National Natural Science Foundation of China(NSFC,Grant Nos.11727805,11703029,11733005 and 12103057)。
文摘For the public having a better understanding of solar activities,the Educational Adaptive-optics Solar Telescope(EAST)was built in July 2021 and is located at the Shanghai Astronomy Museum.The EAST consists of a 65 cm aperture solar telescope with a 177-element adaptive optics system and two-channel high resolution imaging system at the Hαand TiO bands,in addition to three full disk solar telescopes at CaK,Hαand TiO bands equipped on the tube of the main telescope.In this paper,the configuration of the EAST is described.Its performance and on-sky observational results are presented.The EAST,to our knowledge,is the most advanced solar telescope for the popularization of science in the world.Due to its excellent performance,the data acquired by the EAST can also be used for research on solar physics and space weather prediction.
