Suppressing the interference of atmospheric turbulence and obtaining observation data with a high spatial resolution are an issue to be solved urgently for ground observations. One way to solve this problem is to perf...Suppressing the interference of atmospheric turbulence and obtaining observation data with a high spatial resolution are an issue to be solved urgently for ground observations. One way to solve this problem is to perform a statistical reconstruction of short-exposure speckle images. Combining the rapidity of Shift-Add and the accuracy of speckle masking, this paper proposes a novel reconstruction algorithm-NASIR(Non-rigid Alignment based Solar Image Reconstruction). NASIR reconstructs the phase of the object image at each frequency by building a computational model between geometric distortion and intensity distribution and reconstructs the modulus of the object image on the aligned speckle images by speckle interferometry. We analyzed the performance of NASIR by using the correlation coefficient, power spectrum, and coefficient of variation of intensity profile in processing data obtained by the NVST(1 m New Vacuum Solar Telescope). The reconstruction experiments and analysis results show that the quality of images reconstructed by NASIR is close to speckle masking when the seeing is good, while NASIR has excellent robustness when the seeing condition becomes worse. Furthermore, NASIR reconstructs the entire field of view in parallel in one go, without phase recursion and block-by-block reconstruction, so its computation time is less than half that of speckle masking. Therefore, we consider NASIR is a robust and highquality fast reconstruction method that can serve as an effective tool for data filtering and quick look.展开更多
The hard X-ray modulation telescope （HXMT） mission is mainly devoted to performing an all-sky survey at 1- 250 keV with both high sensitivity and high spatial resolution. The observed data reduction as well as the i...The hard X-ray modulation telescope （HXMT） mission is mainly devoted to performing an all-sky survey at 1- 250 keV with both high sensitivity and high spatial resolution. The observed data reduction as well as the image reconstruction for HXMT can be achieved by using the direct demodulation method （DDM）. However the original DDM is too computationally expensive for multi-dimensional data with high resolution to be employed for HXMT data. We propose an accelerated direct demodulation method especially adapted for data from HXMT. Simulations are also presented to demonstrate this method.展开更多
The portable adaptive optics(PAO)device is a low-cost and compact system,designed for 4-meter class telescopes that have no adaptive optics(AO)system,because of the physical space limitation at the Nasmyth or Cassegra...The portable adaptive optics(PAO)device is a low-cost and compact system,designed for 4-meter class telescopes that have no adaptive optics(AO)system,because of the physical space limitation at the Nasmyth or Cassegrain focus and the historically high cost of conventional AO.The initial scientific observations of the PAO are focused on the direct imaging of exoplanets and sub-stellar companions.This paper discusses the concept of PAO and the associated high-contrast imaging performance in our recent observational runs.PAO deliver a Strehl ratio better than 60%in H band under median seeing conditions of 1".Combined with our dedicated image rotation and subtraction(IRS)technique and the optimized IRS(O-IRS)algorithm,the averaged contrast ratio for a 5≤V_(mag)≤9 primary star is 1.3×10^(-5)and3.3×10^(-6)at angular distance of 0.36"with exposure time of 7 minutes and 2 hours,respectively.PAO has successfully revealed the known exoplanet ofκAnd b in our recent observation with the 3.5-meter ARC telescope at Apache Point Observatory.We have performed the associated astrometry and photometry analysis of the recoveredκAnd b planet,which gives a projected separation of 0.98"±0.05",a position angle of 51.1°±0.5°and a mass of 10.15_(-1.255)^(+2.19) MJup.These results demonstrate that PAO can be used for direct imaging of exoplanets with medium-sized telescopes.展开更多
This paper reviewed the developments of the last ten years in the field of international high-resolution earth observation, and introduced the developmental status and plans for China's high-resolution earth obser...This paper reviewed the developments of the last ten years in the field of international high-resolution earth observation, and introduced the developmental status and plans for China's high-resolution earth observation program. In addition, this paper expounded the transformation mechanism and procedure from earth observation data to geospatial information and geographical knowledge, and examined the key scientific and technological issues, including earth observation networks, high-precision image positioning, image understanding, automatic spatial information extraction, and focus services. These analyses provide a new impetus for pushing the application of China's high-resolution earth observation system from a "quantity" to "quality" change, from China to the world, from providing products to providing online service.展开更多
Lucky imaging is a high-resolution astronomical image recovery technique with two classic implementation algorithms,i.e.image selecting,shifting and adding in image space,and data selecting and image synthesizing in F...Lucky imaging is a high-resolution astronomical image recovery technique with two classic implementation algorithms,i.e.image selecting,shifting and adding in image space,and data selecting and image synthesizing in Fourier space.This paper proposes a novel lucky imaging algorithm where with space-domain and frequency-domain selection rates as a link,the two classic algorithms are combined successfully,making each algorithm a proper subset of the novel hybrid algorithm.Experimental results show that with the same experiment dataset and platform,the high-resolution image obtained by the proposed algorithm is superior to that obtained by the two classic algorithms.This paper also proposes a new lucky image selection and storage scheme,which can greatly save computer memory and enable lucky imaging algorithm to be implemented in a common desktop or laptop with small memory and to process astronomical images with more frames and larger size.In addition,through simulation analysis,this paper discusses the binary star detection limits of the novel lucky imaging algorithm and traditional ones under different atmospheric conditions.展开更多
With telescope apertures becoming larger and larger,the deployment of large-field telescopes is becoming increasingly popular.However,optical path calibration is necessary to ensure the image quality of large-field an...With telescope apertures becoming larger and larger,the deployment of large-field telescopes is becoming increasingly popular.However,optical path calibration is necessary to ensure the image quality of large-field and large-diameter telescopes.In particular,focal plane attitude calibration is an essential optical path calibration technique that has a direct impact on image quality.In this paper,a focal plane attitude detection method using eight acquisition cameras is proposed based on the calibration requirements of the wide-field telescope,LAMOST(Large Sky Area Multi-Object Fiber Spectroscopic Telescope).Comparison of simulation and experimental results shows that the detection accuracy of the proposed method can reach 30 arcsec.With additional testing and verification,this method could be used to facilitate regular focal plane attitude calibration for LAMOST as well as other large-field telescopes.展开更多
基金sponsored by the National Natural Science Foundation of China (NSFC) under Grant Nos.11873027, U2031140, 12073077, 11833010 and 11973088West Light Foundation of the Chinese Academy of Sciences (Y9XB01A and Y9XB019)。
文摘Suppressing the interference of atmospheric turbulence and obtaining observation data with a high spatial resolution are an issue to be solved urgently for ground observations. One way to solve this problem is to perform a statistical reconstruction of short-exposure speckle images. Combining the rapidity of Shift-Add and the accuracy of speckle masking, this paper proposes a novel reconstruction algorithm-NASIR(Non-rigid Alignment based Solar Image Reconstruction). NASIR reconstructs the phase of the object image at each frequency by building a computational model between geometric distortion and intensity distribution and reconstructs the modulus of the object image on the aligned speckle images by speckle interferometry. We analyzed the performance of NASIR by using the correlation coefficient, power spectrum, and coefficient of variation of intensity profile in processing data obtained by the NVST(1 m New Vacuum Solar Telescope). The reconstruction experiments and analysis results show that the quality of images reconstructed by NASIR is close to speckle masking when the seeing is good, while NASIR has excellent robustness when the seeing condition becomes worse. Furthermore, NASIR reconstructs the entire field of view in parallel in one go, without phase recursion and block-by-block reconstruction, so its computation time is less than half that of speckle masking. Therefore, we consider NASIR is a robust and highquality fast reconstruction method that can serve as an effective tool for data filtering and quick look.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11173038 and 11103022)the Tsinghua University Initiative Scientific Research Program (Grant No. 20111081102)
文摘The hard X-ray modulation telescope （HXMT） mission is mainly devoted to performing an all-sky survey at 1- 250 keV with both high sensitivity and high spatial resolution. The observed data reduction as well as the image reconstruction for HXMT can be achieved by using the direct demodulation method （DDM）. However the original DDM is too computationally expensive for multi-dimensional data with high resolution to be employed for HXMT data. We propose an accelerated direct demodulation method especially adapted for data from HXMT. Simulations are also presented to demonstrate this method.
基金supported by the National Natural Science Foundation of China(Grant Nos.11827804,U2031210)。
文摘The portable adaptive optics(PAO)device is a low-cost and compact system,designed for 4-meter class telescopes that have no adaptive optics(AO)system,because of the physical space limitation at the Nasmyth or Cassegrain focus and the historically high cost of conventional AO.The initial scientific observations of the PAO are focused on the direct imaging of exoplanets and sub-stellar companions.This paper discusses the concept of PAO and the associated high-contrast imaging performance in our recent observational runs.PAO deliver a Strehl ratio better than 60%in H band under median seeing conditions of 1".Combined with our dedicated image rotation and subtraction(IRS)technique and the optimized IRS(O-IRS)algorithm,the averaged contrast ratio for a 5≤V_(mag)≤9 primary star is 1.3×10^(-5)and3.3×10^(-6)at angular distance of 0.36"with exposure time of 7 minutes and 2 hours,respectively.PAO has successfully revealed the known exoplanet ofκAnd b in our recent observation with the 3.5-meter ARC telescope at Apache Point Observatory.We have performed the associated astrometry and photometry analysis of the recoveredκAnd b planet,which gives a projected separation of 0.98"±0.05",a position angle of 51.1°±0.5°and a mass of 10.15_(-1.255)^(+2.19) MJup.These results demonstrate that PAO can be used for direct imaging of exoplanets with medium-sized telescopes.
基金supported by National Basic Research Program of China(Grant No. 2012CB719906)
文摘This paper reviewed the developments of the last ten years in the field of international high-resolution earth observation, and introduced the developmental status and plans for China's high-resolution earth observation program. In addition, this paper expounded the transformation mechanism and procedure from earth observation data to geospatial information and geographical knowledge, and examined the key scientific and technological issues, including earth observation networks, high-precision image positioning, image understanding, automatic spatial information extraction, and focus services. These analyses provide a new impetus for pushing the application of China's high-resolution earth observation system from a "quantity" to "quality" change, from China to the world, from providing products to providing online service.
基金This work is supported by the National Natural Science Foundation of China(Grant No.11673009).
文摘Lucky imaging is a high-resolution astronomical image recovery technique with two classic implementation algorithms,i.e.image selecting,shifting and adding in image space,and data selecting and image synthesizing in Fourier space.This paper proposes a novel lucky imaging algorithm where with space-domain and frequency-domain selection rates as a link,the two classic algorithms are combined successfully,making each algorithm a proper subset of the novel hybrid algorithm.Experimental results show that with the same experiment dataset and platform,the high-resolution image obtained by the proposed algorithm is superior to that obtained by the two classic algorithms.This paper also proposes a new lucky image selection and storage scheme,which can greatly save computer memory and enable lucky imaging algorithm to be implemented in a common desktop or laptop with small memory and to process astronomical images with more frames and larger size.In addition,through simulation analysis,this paper discusses the binary star detection limits of the novel lucky imaging algorithm and traditional ones under different atmospheric conditions.
基金the National Natural Science Foundation of China(Grant No.U1931207)Funding for the project has been provided by the National Development and Reform Commission。
文摘With telescope apertures becoming larger and larger,the deployment of large-field telescopes is becoming increasingly popular.However,optical path calibration is necessary to ensure the image quality of large-field and large-diameter telescopes.In particular,focal plane attitude calibration is an essential optical path calibration technique that has a direct impact on image quality.In this paper,a focal plane attitude detection method using eight acquisition cameras is proposed based on the calibration requirements of the wide-field telescope,LAMOST(Large Sky Area Multi-Object Fiber Spectroscopic Telescope).Comparison of simulation and experimental results shows that the detection accuracy of the proposed method can reach 30 arcsec.With additional testing and verification,this method could be used to facilitate regular focal plane attitude calibration for LAMOST as well as other large-field telescopes.
