Since the Industrial Revolution,the pursuit of lighting for humanity has gradually evolved into an out-of-control disaster of light pollution.Artificial light at night(ALAN)scatters the constituents of the atmosphere(...Since the Industrial Revolution,the pursuit of lighting for humanity has gradually evolved into an out-of-control disaster of light pollution.Artificial light at night(ALAN)scatters the constituents of the atmosphere(such as gas molecules,aerosols,and clouds),causing the artificial glow to brighten the night sky during observations.1 The unrestrained expansion of urban lighting systems and the unrestrained flashing of commercial neon lights have led to an annual increase of 6%in the brightness of the night sky.Around the city,people can no longer see the Milky Way with the naked eye.This kind of light pollution not only obscures the starry sky but also disrupts the circadian rhythm that has formed in the ecosystem of Earth over millions of years;every year,millions of birds lose their way due to the strong light in cities and crash into tall buildings.The foraging and breeding behaviors of nocturnal animals have been severely disrupted,and biodiversity continues to decline.Human health itself is also threatened.Excessive night light can inhibit the secretion of melatonin and increase the risk of cancer and cardiovascular diseases.展开更多
Deconvolution in radio interferometry faces challenges due to incomplete sampling of the visibilities in the spatial frequency domain caused by a limited number of antenna baselines,resulting in an ill-posed inverse p...Deconvolution in radio interferometry faces challenges due to incomplete sampling of the visibilities in the spatial frequency domain caused by a limited number of antenna baselines,resulting in an ill-posed inverse problem.Reconstructing dirty images into clean ones is crucial for subsequent scientific analysis.To address these challenges,we propose a U-Net based method that extracts high-level information from the dirty image and reconstructs a clean image by effectively reducing artifacts and sidelobes.The U-Net architecture,consisting of an encoder-decoder structure and skip connections,facilitates the flow of information and preserves spatial details.Using simulated data of radio galaxies,we train our model and evaluate its performance on the testing set.Compared with the CLEAN method and the visibility and image conditioned denoising diffusion probabilistic model,our proposed model can effectively reconstruct both extended sources and faint point sources with higher values in the structural similarity index measure and the peak signal-to-noise ratio.Furthermore,we investigate the impact of noise on the model performance,demonstrating its robustness under varying noise levels.展开更多
Astronomical spectroscopy is crucial for exploring the physical properties,chemical composition,and kinematic behavior of celestial objects.With continuous advancements in observational technology,astronomical spectro...Astronomical spectroscopy is crucial for exploring the physical properties,chemical composition,and kinematic behavior of celestial objects.With continuous advancements in observational technology,astronomical spectroscopy faces the dual challenges of rapidly expanding data volumes and relatively lagging data processing capabilities.In this context,the rise of artificial intelligence technologies offers an innovative solution to address these challenges.This paper analyzes the latest developments in the application of machine learning for astronomical spectral data mining and discusses future research directions in AI-based spectral studies.However,the application of machine learning technologies presents several challenges.The high complexity of models often comes with insufficient interpretability,complicating scientific understanding.Moreover,the large-scale computational demands place higher requirements on hardware resources,leading to a significant increase in computational costs.AI-based astronomical spectroscopy research should advance in the following key directions.First,develop efficient data augmentation techniques to enhance model generalization capabilities.Second,explore more interpretable model designs to ensure the reliability and transparency of scientific conclusions.Third,optimize computational efficiency and reduce the threshold for deep-learning applications through collaborative innovations in algorithms and hardware.Furthermore,promoting the integration of cross-band data processing is essential to achieve seamless integration and comprehensive analysis of multi-source data,providing richer,multidimensional information to uncover the mysteries of the universe.展开更多
Astronomical site selection work is very hard.Unmanned technologies are important trends and solutions.We present a relatively easy method to plan a high reliability site selection which can extend the time from site ...Astronomical site selection work is very hard.Unmanned technologies are important trends and solutions.We present a relatively easy method to plan a high reliability site selection which can extend the time from site deployment to returning for maintaining by unmanned confirming the site.First,we redefine the reliability of a site selection deployment with the parameter of the trusty time,which means when we must return,and which can be relatively easy for estimating.The redefinition makes the reliability parameter as a Bayesian probability,and can be obtained by estimating besides testing,which makes the evaluation of each device's reliability much easier.Then we use block diagram tools in the Matlab Simulink software to construct structure diagram,and to link each component with relations of parallel,serial,protection,and so on.This makes the whole reliability value can be calculated at the time when we design or plan a site selection.We applied this concept and method in an actual site selection in Lenghu,Qinghai Province,China.The survey practice reveals its effectiveness and simpleness.展开更多
We evaluate the performance of the first generation scientific CMOS （sC- MOS） camera used for astronomical observations. The sCMOS camera was attached to a 25 cm telescope at Xinglong Observatory, in order to estima...We evaluate the performance of the first generation scientific CMOS （sC- MOS） camera used for astronomical observations. The sCMOS camera was attached to a 25 cm telescope at Xinglong Observatory, in order to estimate its photometric capabilities. We further compared the capabilities of the sCMOS camera with that of full-frame and electron multiplying CCD cameras in laboratory tests and observations. The results indicate the sCMOS camera is capable of performing photometry of bright sources, especially when high spatial resolution or temporal resolution is desired.展开更多
Astronomical cross-matching is a basic method for aggregating the observational data of different wavelengths. By data aggregation, the properties of astronomical objects can be understood comprehensively. Aiming at d...Astronomical cross-matching is a basic method for aggregating the observational data of different wavelengths. By data aggregation, the properties of astronomical objects can be understood comprehensively. Aiming at decreasing the time consumed on I/O operations, several improved methods are introduced, including a processing flow based on the boundary growing model, which can reduce the database query operations; a concept of the biggest growing block and its determination which can improve the performance of task partition and resolve data-sparse problem; and a fast bitwise algorithm to compute the index numbers of the neighboring blocks, which is a significant efficiency guarantee. Experiments show that the methods can effectively speed up cross-matching on both sparse datasets and high-density datasets.展开更多
To evaluate performances of a back-illuminated scientific CMOS(sCMOS)camera for astronomical observations,comparison tests between Andor Marana s CMOS and Andor iKon-L 936 CCD cameras were conducted in a laboratory an...To evaluate performances of a back-illuminated scientific CMOS(sCMOS)camera for astronomical observations,comparison tests between Andor Marana s CMOS and Andor iKon-L 936 CCD cameras were conducted in a laboratory and on a telescope.The laboratory tests showed that the readout noise of the sCMOS camera is about half lower,the dark current is about 17 times higher,the dynamic range is lower in the 12-bit setting and higher in the 16-bit setting,and the linearity and bias stability are comparable relative to those of the CCD camera.In field tests,we observed the open cluster M67 with the sCMOS and CCD cameras on a 60 cm telescope.Unlike the CCD camera,the sCMOS camera has a dual-amplifier architecture.Since a 16-bit image of the sCMOS camera is composed of two 12-bit images sampled with 12-bit high gain and low gain amplifiers simultaneously,it is not real 16-bit output data.The evaluation tests indicated that the dual-amplifier architecture of the s CMOS camera leads to a decline of photometric stability by about six times around specific pixel counts.For photometry of bright objects with similar magnitudes that require high frame rates,the s CMOS camera under 12-bit setting is a good choice.Therefore,the sCMOS camera is fitted with survey observations of variable objects requiring short exposure times,mostly less than 1 s,and high frame rates.It also satisfies the requirements for an offset guiding instrument owing to its high sensitivity,high temporal resolution and high stability.展开更多
Astronomical knowledge entities,such as celestial object identifiers,are crucial for literature retrieval and knowledge graph construction,and other research and applications in the field of astronomy.Traditional meth...Astronomical knowledge entities,such as celestial object identifiers,are crucial for literature retrieval and knowledge graph construction,and other research and applications in the field of astronomy.Traditional methods of extracting knowledge entities from texts face numerous challenging obstacles that are difficult to overcome.Consequently,there is a pressing need for improved methods to efficiently extract them.This study explores the potential of pre-trained Large Language Models(LLMs)to perform astronomical knowledge entity extraction(KEE)task from astrophysical journal articles using prompts.We propose a prompting strategy called PromptKEE,which includes five prompt elements,and design eight combination prompts based on them.We select four representative LLMs(Llama-2-70B,GPT-3.5,GPT-4,and Claude 2)and attempt to extract the most typical astronomical knowledge entities,celestial object identifiers and telescope names,from astronomical journal articles using these eight combination prompts.To accommodate their token limitations,we construct two data sets:the full texts and paragraph collections of 30 articles.Leveraging the eight prompts,we test on full texts with GPT-4and Claude 2,on paragraph collections with all LLMs.The experimental results demonstrate that pre-trained LLMs show significant potential in performing KEE tasks,but their performance varies on the two data sets.Furthermore,we analyze some important factors that influence the performance of LLMs in entity extraction and provide insights for future KEE tasks in astrophysical articles using LLMs.Finally,compared to other methods of KEE,LLMs exhibit strong competitiveness in multiple aspects.展开更多
This paper presents an ultra-low noise L-band radio astronomical cryogenic receiver for the Fivehundred-meter Aperture Spherical radio Telescope(FAST) telescope. The development of key low noise microwave parts of cou...This paper presents an ultra-low noise L-band radio astronomical cryogenic receiver for the Fivehundred-meter Aperture Spherical radio Telescope(FAST) telescope. The development of key low noise microwave parts of coupling low noise amplifier(Coupling-LNA) and conical quad-ridge orthogonal mode transducers(OMT) and reasonable system integration achieve outstanding performance of receiver. It covers the frequency range of 1.2 GHz to 1.8 GHz. Novel cryogenic Coupling-LNAs with low noise, large return loss, high dynamic range and the function of coupling calibration signals are developed for the proposed receiver. Amplification and coupling function circuits are integrated as a single Coupling-LNA with full noise temperature of 4 K at the physical temperature of 15 K. Its return loss is more than 18 d B, and output1 d B compression power is +5 d Bm. A cryogenic dewar is fabricated to provide 55 K and 15 K cryogenic environment for OMT and Coupling-LNAs, respectively. The receiver's system noise temperature is below9 K referred to feed aperture plane. Benefiting from optimal design and precise mechanical treatment, good scattering performance of OMT and equalized radiation patterns of horn are achieved with an antenna efficiency above 75%.展开更多
Artificial Intelligence(AI)is an interdisciplinary research field with widespread applications.It aims at developing theoretical,methodological,technological,and applied systems that simulate,enhance,and assist human ...Artificial Intelligence(AI)is an interdisciplinary research field with widespread applications.It aims at developing theoretical,methodological,technological,and applied systems that simulate,enhance,and assist human intelligence.Recently,notable accomplishments of artificial intelligence technology have been achieved in astronomical data processing,establishing this technology as central to numerous astronomical research areas such as radio astronomy,stellar and galactic(Milky Way)studies,exoplanets surveys,cosmology,and solar physics.This article systematically reviews representative applications of artificial intelligence technology to astronomical data processing,with comprehensive description of specific cases:pulsar candidate identification,fast radio burst detection,gravitational wave detection,spectral classification,and radio frequency interference mitigation.Furthermore,it discusses possible future applications to provide perspectives for astronomical research in the artificial intelligence era.展开更多
Astronomical outliers,such as unusual,rare or unknown types of astronomical objects or phenomena,constantly lead to the discovery of genuinely unforeseen knowledge in astronomy.More unpredictable outliers will be unco...Astronomical outliers,such as unusual,rare or unknown types of astronomical objects or phenomena,constantly lead to the discovery of genuinely unforeseen knowledge in astronomy.More unpredictable outliers will be uncovered in principle with the increment of the coverage and quality of upcoming survey data.However,it is a severe challenge to mine rare and unexpected targets from enormous data with human inspection due to a significant workload.Supervised learning is also unsuitable for this purpose because designing proper training sets for unanticipated signals is unworkable.Motivated by these challenges,we adopt unsupervised machine learning approaches to identify outliers in the data of galaxy images to explore the paths for detecting astronomical outliers.For comparison,we construct three methods,which are built upon the k-nearest neighbors(KNN),Convolutional Auto-Encoder(CAE)+KNN,and CAE+KNN+Attention Mechanism(att CAE_KNN)separately.Testing sets are created based on the Galaxy Zoo image data published online to evaluate the performance of the above methods.Results show that att CAE_KNN achieves the best recall(78%),which is 53%higher than the classical KNN method and 22%higher than CAE+KNN.The efficiency of att CAE_KNN(10 minutes)is also superior to KNN(4 h)and equal to CAE+KNN(10 minutes)for accomplishing the same task.Thus,we believe that it is feasible to detect astronomical outliers in the data of galaxy images in an unsupervised manner.Next,we will apply att CAE_KNN to available survey data sets to assess its applicability and reliability.展开更多
With the application of advanced astronomical technologies, equipments and methods all over the world, astronomical observations cover the range from radio, infrared, visible light, ultraviolet, X-ray and gamma-ray ba...With the application of advanced astronomical technologies, equipments and methods all over the world, astronomical observations cover the range from radio, infrared, visible light, ultraviolet, X-ray and gamma-ray bands, and enter into the era of full wavelength astronomy. How to effectively integrate data from different ground- and space-based observation equipments, different observers, different bands and different observation times, requires data fusion technology. In this paper we introduce a cross-match tool that is developed in the Python language, is based on the PostgreSQL database and uses Q3C as the core index, facilitating the cross-match work of massive astronomical data. It provides four different cross- match functions, namely： （I） cross-match of the custom error range; （II） cross-match of catalog errors; （III） cross-match based on the elliptic error range; （IV） cross-match of the nearest neighbor algorithm. The resulting cross-matched set provides a good foundation for subsequent data mining and statistics based on multiwavelength data. The most advantageous aspect of this tool is a user-oriented tool applied locally by users. By means of this tool, users can easily create their own databases, manage their own data and cross- match databases according to their requirements. In addition, this tool is also able to transfer data from one database into another database. More importantly, it is easy to get started with the tool and it can be used by astronomers without writing any code.展开更多
Digital channelization decomposes a wideband signal into multiple adjacent sub-bands using Parallel Technology.Channelization can effectively reduce the pressure on the radio astronomy digital backends system and make...Digital channelization decomposes a wideband signal into multiple adjacent sub-bands using Parallel Technology.Channelization can effectively reduce the pressure on the radio astronomy digital backends system and make wideband signal processing possible.Aiming at the problems of signal attenuation at sub-band edge,spectral leakage and aliasing encountered in wideband signal channelization,algorithms to reduce the problems are studied.We design a Critically Sampled Polyphase Filter Bank(CS-PFB)based on the Finite Impulse Response digital filter with a Hamming Window and systematically analyze the frequency response characteristics of the CS-PFB.Based on the channelized structure of the CS-PFB,an Over Sampled Polyphase Filter Bank(OS-PFB)is designed by data reuse,and the filtering frequency response characteristics of CS-PFB and OS-PFB are compared and analyzed.Using the wideband baseband data generated by the CASPSR(Collaboration for Astronomy Signal processing and electronics research Parkes Swinburne Recorder),we implement sub-band division and 16-band output of these data based on the 2×oversampling OS-PFB,and the problem of spectrum inversion in the sub-bands is corrected.After removing 25%of redundant data in the head and tail of each sub-band,we recombine the sub-bands into a wideband.The wideband signal is almost identical to the original observed signal.Therefore,the experimental results show that the OS-PFB can improve the channel response.For the 400 MHz baseband data of J0437-4715,we compare the pulse profile obtained from the original baseband data with the pulse profile obtained after the channelization and recombination.The phase and amplitude information of the pulse profiles are consistent,which verifies the correctness of our channelization algorithm.展开更多
A large ground-based optical/infrared telescope is being planned for a world-class astronomical site in China.The cloud-free night percentage is the primary meteorological consideration for evaluating candidate sites....A large ground-based optical/infrared telescope is being planned for a world-class astronomical site in China.The cloud-free night percentage is the primary meteorological consideration for evaluating candidate sites.The data from GMS and NOAA satellites and the MODIS instrument were utilized in this research,covering the period from 1996 to 2015.Our data analysis benefits from overlapping results from different independent teams as well as a uniform analysis of selected sites using GMS+NOAA data.Although significant ground-based monitoring is needed to validate these findings,we identify three different geographical regions with a high percentage of cloud-free conditions(~83%on average),which is slightly lower than at Mauna Kea and Cerro Armazones(~85%on average)and were chosen for the large international projects TMT and ELT respectively.Our study finds evidence that cloud distributions and the seasonal changes affected by the prevailing westerly winds and summer monsoons reduce the cloud cover in areas influenced by the westerlies.This is consistent with the expectations from climate change models and is suggestive that most of the identified sites will have reduced cloud cover in the future.展开更多
The Earth is buffered from the ferocious onslaught of the solar wind by a thin layer of matter known as the atmosphere and geospace.This layer absorbs energy from irradiance and outburst from the Sun,as well as from d...The Earth is buffered from the ferocious onslaught of the solar wind by a thin layer of matter known as the atmosphere and geospace.This layer absorbs energy from irradiance and outburst from the Sun,as well as from disasters,transient phenomena and anthropogenic emissions originated from Earth.Through complicated physics,the absorbed energy changes the atmospheric and geospace state and sometimes gets re-released to power extreme events such as space weather.Taking place globally,these complicated processes cannot be understood unless they are studied globally.The Chinese scientists have proposed the International Meridian Circle Program(IMCP)to meet this demand.By operating nearly 1000 instruments encompassing all latitudes along with the 120°E–60°W longitudes,IMCP aims,for the first time,to construct comprehensive 3D data representation of the atmosphere and geospace on a global scale and empower interdisciplinary research to tackle key questions related to Earth’s environment and climate change.展开更多
We will introduce the construction and design of a new simultaneous three-channel multicolor CCD photometer.This photometer has been mounted on the 1.2 m telescope at Jilin Astronomical Observatory,and is applied to s...We will introduce the construction and design of a new simultaneous three-channel multicolor CCD photometer.This photometer has been mounted on the 1.2 m telescope at Jilin Astronomical Observatory,and is applied to study space debris,gamma-ray burst afterglows,asteroids and other rapidly variable objects.As one of the ground follow-up telescopes of the Chinese-French Space-based multi-band astronomical Variable Objects Monitor(SVOM)mission,it appears very essential to evaluate the performance of the photometry system of this photometer,which can achieve simultaneous imaging within a field of view of 21’.5×21’.5,21’.5×21’.5 and21’.3×21’.3 in the Sloan Digital Sky Survey(SDSS)g’,r’,i’bands,respectively.Photometric calibrations were carried out by using plenty of SDSS standard stars,and the relationship between the photometric system and the Johnson-Bessel filter system was also studied.The results of the performance evaluation from observing open cluster M67 are presented.展开更多
Based on previous site testing and satellite cloud data,Ali,Daocheng and Muztagh-ata have been selected as candidate sites for the Large Optical/Infrared Telescope(LOT) in China.We present the data collection,processi...Based on previous site testing and satellite cloud data,Ali,Daocheng and Muztagh-ata have been selected as candidate sites for the Large Optical/Infrared Telescope(LOT) in China.We present the data collection,processing,management and quality analysis for our site testing based on using similar hardware.We analyze meteorological data,seeing,background light,cloud and precipitable water vapor data from 2017 March 10 to 2019 March 10.We also investigated the relative usefulness of our all-sky camera data in comparison to that from the meteorological TERRA satellite data based on a night-by-night comparison of the correlation and consistency between them.We find a 6% discrepancy arising from a wide range of factors.展开更多
From the mid-19th century to the end of the 20th century, photographic plates served as the primary detectors for astronomical observations. Astronomical photographic observations in China began in 1901, and over a ce...From the mid-19th century to the end of the 20th century, photographic plates served as the primary detectors for astronomical observations. Astronomical photographic observations in China began in 1901, and over a century, a total of approximately 30,000 astronomical photographic plates were captured. These historical plates play an irreplaceable role in conducting long-term, time-domain astronomical research. To preserve and explore these valuable original astronomical observational data, Shanghai Astronomical Observatory has organized the transportation of plates, taken during nighttime observations from various stations across the country, to the Sheshan Plate Archive for centralized preservation. For the first time, plate information statistics were calculated. On this basis, the plates were cleaned and digitally scanned, and finally digitized images were acquired for 29,314 plates. In this study, using Gaia DR2 as the reference star catalog, astrometric processing was carried out successfully on 15,696 single-exposure plates, including object extraction, stellar identification,and plate model computation. As a result, for long focal length telescopes, such as the 40 cm double-tube refractor telescope, the 1.56 m reflector telescope at Shanghai Astronomical Observatory, and the 1m reflecting telescope at Yunnan Astronomical Observatory, the astrometric accuracy obtained for their plates is approximately 0."1–0."3. The distribution of astrometric accuracy for medium and short focal length telescopes ranges from 0."3 to 1."0. The relevant data of this batch of plates, including digitized images and a stellar catalog of the plates, are archived and released by the National Astronomical Data Center. Users can access and download plate data based on keywords such as station, telescope, observation year, and observed celestial coordinates.展开更多
Transmission efficiency(TE) and focal ratio degradation(FRD) are two important parameters for evaluating the quality of an optical fiber system used for astronomy. Compared to TE, the focal ratio is more easily influe...Transmission efficiency(TE) and focal ratio degradation(FRD) are two important parameters for evaluating the quality of an optical fiber system used for astronomy. Compared to TE, the focal ratio is more easily influenced by external factors, such as bending or stress. Optical cables are widely implemented for multi-object telescopes and integral field units(IFUs). The design and fabrication process of traditional optical cables seldom considers the requirements of astronomical applications. In this paper, we describe a fiber bundle structure as the basic unit for miniaturized high-density FASOT-IFU optical cables,instead of the micro-tube structure in stranded cables. Seven fibers with hexagonal arrangement were accurately positioned by ultraviolet(UV)-curing acrylate to form the bundle. The coating diameter of a fiber is0.125 mm, and the outer diameter of the bundle is 0.58 mm. Compared with the 0.8 mm micro-tube structure of a traditional stranded cable, the outer diameter of the fiber bundle was reduced by 27.5%. Fiber paste was filled into the bundle to reduce stress between the fibers. We tested the output focal ratio(OFR) in95% of the encircled energy(EE95) of the fibers in the bundle under different conditions. With the incident focal ratio F/8, the maximum difference of OFR is 0.6. In particular, when the incident focal ratio is F/5,the maximum difference of OFR is only 0.1. The jacket formed by the UV-curing acrylate can withstand a certain stress of less than 1.38 N mm-1. The fiber bundle can maintain uniform emitting characteristics with a bending radius of 7.5 cm and with tension less than 6 N. The test results show that the structure of the fiber bundle can be used as a basic unit for miniaturized high-density astronomical optical cables.展开更多
This work shows details of an evaluation of an observational system comprising a complementary metal-oxidesemiconductor detector, 60 cm telescope and filter complement. The system’s photometric precision and differen...This work shows details of an evaluation of an observational system comprising a complementary metal-oxidesemiconductor detector, 60 cm telescope and filter complement. The system’s photometric precision and differential photometric precision, and extinction coefficients were assessed through observations of Supersky flat fields, open clusters, standard stars and exoplanets. Photometry was precision achieved at the 0.02 mag level, with differential photometry of 0.004 mag precision. Extinction was found to agree with previous studies conducted at Xinglong Observatory. Ultimately, the results demonstrate this observing system is capable of precision scientific observations with a charge-coupled device across the optical wavelengths.展开更多
基金supported by Strategic Priority Research Program of the Chinese Academy of Sciences grant XDB0550100by the Foundation of China Association for Science and Technology(CAST)under grants kpbwh-2023-3-03 and kpbwh-2024-2-08.
文摘Since the Industrial Revolution,the pursuit of lighting for humanity has gradually evolved into an out-of-control disaster of light pollution.Artificial light at night(ALAN)scatters the constituents of the atmosphere(such as gas molecules,aerosols,and clouds),causing the artificial glow to brighten the night sky during observations.1 The unrestrained expansion of urban lighting systems and the unrestrained flashing of commercial neon lights have led to an annual increase of 6%in the brightness of the night sky.Around the city,people can no longer see the Milky Way with the naked eye.This kind of light pollution not only obscures the starry sky but also disrupts the circadian rhythm that has formed in the ecosystem of Earth over millions of years;every year,millions of birds lose their way due to the strong light in cities and crash into tall buildings.The foraging and breeding behaviors of nocturnal animals have been severely disrupted,and biodiversity continues to decline.Human health itself is also threatened.Excessive night light can inhibit the secretion of melatonin and increase the risk of cancer and cardiovascular diseases.
基金supported by the National SKA Program of China(2020SKA0110300,2020SKA0110201)the National Natural Science Foundation of China(NSFC,grant Nos.12433012 and 12373097)+1 种基金the Guangdong Province Project of the Basic and Applied Basic Research Foundation(2024A1515011503)the Guangzhou Science and Technology Funds(2023A03J0016).
文摘Deconvolution in radio interferometry faces challenges due to incomplete sampling of the visibilities in the spatial frequency domain caused by a limited number of antenna baselines,resulting in an ill-posed inverse problem.Reconstructing dirty images into clean ones is crucial for subsequent scientific analysis.To address these challenges,we propose a U-Net based method that extracts high-level information from the dirty image and reconstructs a clean image by effectively reducing artifacts and sidelobes.The U-Net architecture,consisting of an encoder-decoder structure and skip connections,facilitates the flow of information and preserves spatial details.Using simulated data of radio galaxies,we train our model and evaluate its performance on the testing set.Compared with the CLEAN method and the visibility and image conditioned denoising diffusion probabilistic model,our proposed model can effectively reconstruct both extended sources and faint point sources with higher values in the structural similarity index measure and the peak signal-to-noise ratio.Furthermore,we investigate the impact of noise on the model performance,demonstrating its robustness under varying noise levels.
基金supported by the National Key R&D Program of China(2021YFC2203502 and 2022YFF0711502)the National Natural Science Foundation of China(NSFC)(12173077)+4 种基金the Tianshan Talent Project of Xinjiang Uygur Autonomous Region(2022TSYCCX0095 and 2023TSYCCX0112)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(PTYQ2022YZZD01)China National Astronomical Data Center(NADC)the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China(MOF)and administrated by the Chinese Academy of SciencesNatural Science Foundation of Xinjiang Uygur Autonomous Region(2022D01A360).
文摘Astronomical spectroscopy is crucial for exploring the physical properties,chemical composition,and kinematic behavior of celestial objects.With continuous advancements in observational technology,astronomical spectroscopy faces the dual challenges of rapidly expanding data volumes and relatively lagging data processing capabilities.In this context,the rise of artificial intelligence technologies offers an innovative solution to address these challenges.This paper analyzes the latest developments in the application of machine learning for astronomical spectral data mining and discusses future research directions in AI-based spectral studies.However,the application of machine learning technologies presents several challenges.The high complexity of models often comes with insufficient interpretability,complicating scientific understanding.Moreover,the large-scale computational demands place higher requirements on hardware resources,leading to a significant increase in computational costs.AI-based astronomical spectroscopy research should advance in the following key directions.First,develop efficient data augmentation techniques to enhance model generalization capabilities.Second,explore more interpretable model designs to ensure the reliability and transparency of scientific conclusions.Third,optimize computational efficiency and reduce the threshold for deep-learning applications through collaborative innovations in algorithms and hardware.Furthermore,promoting the integration of cross-band data processing is essential to achieve seamless integration and comprehensive analysis of multi-source data,providing richer,multidimensional information to uncover the mysteries of the universe.
基金supported by the Investigation of Technological Infrastructure Resources(No.2023FY101101)the National Natural Science Foundation of China(NSFC)(No.11073027 and No.12373104)。
文摘Astronomical site selection work is very hard.Unmanned technologies are important trends and solutions.We present a relatively easy method to plan a high reliability site selection which can extend the time from site deployment to returning for maintaining by unmanned confirming the site.First,we redefine the reliability of a site selection deployment with the parameter of the trusty time,which means when we must return,and which can be relatively easy for estimating.The redefinition makes the reliability parameter as a Bayesian probability,and can be obtained by estimating besides testing,which makes the evaluation of each device's reliability much easier.Then we use block diagram tools in the Matlab Simulink software to construct structure diagram,and to link each component with relations of parallel,serial,protection,and so on.This makes the whole reliability value can be calculated at the time when we design or plan a site selection.We applied this concept and method in an actual site selection in Lenghu,Qinghai Province,China.The survey practice reveals its effectiveness and simpleness.
文摘We evaluate the performance of the first generation scientific CMOS （sC- MOS） camera used for astronomical observations. The sCMOS camera was attached to a 25 cm telescope at Xinglong Observatory, in order to estimate its photometric capabilities. We further compared the capabilities of the sCMOS camera with that of full-frame and electron multiplying CCD cameras in laboratory tests and observations. The results indicate the sCMOS camera is capable of performing photometry of bright sources, especially when high spatial resolution or temporal resolution is desired.
基金Supported by National Natural Science Foundation of China (No.10978016)Natural Science Foundation of Tianjin (No. 08JCZDJC19700)Key Technologies Research and Development Program of Tianjin (No.09ZCKFGX00400)
文摘Astronomical cross-matching is a basic method for aggregating the observational data of different wavelengths. By data aggregation, the properties of astronomical objects can be understood comprehensively. Aiming at decreasing the time consumed on I/O operations, several improved methods are introduced, including a processing flow based on the boundary growing model, which can reduce the database query operations; a concept of the biggest growing block and its determination which can improve the performance of task partition and resolve data-sparse problem; and a fast bitwise algorithm to compute the index numbers of the neighboring blocks, which is a significant efficiency guarantee. Experiments show that the methods can effectively speed up cross-matching on both sparse datasets and high-density datasets.
基金supported by the National Natural Science Foundation of China(Grant Nos.U1831209,11803017 and 11903053)。
文摘To evaluate performances of a back-illuminated scientific CMOS(sCMOS)camera for astronomical observations,comparison tests between Andor Marana s CMOS and Andor iKon-L 936 CCD cameras were conducted in a laboratory and on a telescope.The laboratory tests showed that the readout noise of the sCMOS camera is about half lower,the dark current is about 17 times higher,the dynamic range is lower in the 12-bit setting and higher in the 16-bit setting,and the linearity and bias stability are comparable relative to those of the CCD camera.In field tests,we observed the open cluster M67 with the sCMOS and CCD cameras on a 60 cm telescope.Unlike the CCD camera,the sCMOS camera has a dual-amplifier architecture.Since a 16-bit image of the sCMOS camera is composed of two 12-bit images sampled with 12-bit high gain and low gain amplifiers simultaneously,it is not real 16-bit output data.The evaluation tests indicated that the dual-amplifier architecture of the s CMOS camera leads to a decline of photometric stability by about six times around specific pixel counts.For photometry of bright objects with similar magnitudes that require high frame rates,the s CMOS camera under 12-bit setting is a good choice.Therefore,the sCMOS camera is fitted with survey observations of variable objects requiring short exposure times,mostly less than 1 s,and high frame rates.It also satisfies the requirements for an offset guiding instrument owing to its high sensitivity,high temporal resolution and high stability.
基金supported by the National Natural Science Foundation of China(NSFC,Grant Nos.12273077,72101068,12373110,and 12103070)National Key Research and Development Program of China under grants(2022YFF0712400,2022YFF0711500)+2 种基金the 14th Five-year Informatization Plan of Chinese Academy of Sciences(CAS-WX2021SF-0204)supported by Astronomical Big Data Joint Research Centerco-founded by National Astronomical Observatories,Chinese Academy of Sciences and Alibaba Cloud。
文摘Astronomical knowledge entities,such as celestial object identifiers,are crucial for literature retrieval and knowledge graph construction,and other research and applications in the field of astronomy.Traditional methods of extracting knowledge entities from texts face numerous challenging obstacles that are difficult to overcome.Consequently,there is a pressing need for improved methods to efficiently extract them.This study explores the potential of pre-trained Large Language Models(LLMs)to perform astronomical knowledge entity extraction(KEE)task from astrophysical journal articles using prompts.We propose a prompting strategy called PromptKEE,which includes five prompt elements,and design eight combination prompts based on them.We select four representative LLMs(Llama-2-70B,GPT-3.5,GPT-4,and Claude 2)and attempt to extract the most typical astronomical knowledge entities,celestial object identifiers and telescope names,from astronomical journal articles using these eight combination prompts.To accommodate their token limitations,we construct two data sets:the full texts and paragraph collections of 30 articles.Leveraging the eight prompts,we test on full texts with GPT-4and Claude 2,on paragraph collections with all LLMs.The experimental results demonstrate that pre-trained LLMs show significant potential in performing KEE tasks,but their performance varies on the two data sets.Furthermore,we analyze some important factors that influence the performance of LLMs in entity extraction and provide insights for future KEE tasks in astrophysical articles using LLMs.Finally,compared to other methods of KEE,LLMs exhibit strong competitiveness in multiple aspects.
基金supported by the National Key R&D Program of China(2018YFE0202900)the National Natural Science Foundation of China(U1831110)。
文摘This paper presents an ultra-low noise L-band radio astronomical cryogenic receiver for the Fivehundred-meter Aperture Spherical radio Telescope(FAST) telescope. The development of key low noise microwave parts of coupling low noise amplifier(Coupling-LNA) and conical quad-ridge orthogonal mode transducers(OMT) and reasonable system integration achieve outstanding performance of receiver. It covers the frequency range of 1.2 GHz to 1.8 GHz. Novel cryogenic Coupling-LNAs with low noise, large return loss, high dynamic range and the function of coupling calibration signals are developed for the proposed receiver. Amplification and coupling function circuits are integrated as a single Coupling-LNA with full noise temperature of 4 K at the physical temperature of 15 K. Its return loss is more than 18 d B, and output1 d B compression power is +5 d Bm. A cryogenic dewar is fabricated to provide 55 K and 15 K cryogenic environment for OMT and Coupling-LNAs, respectively. The receiver's system noise temperature is below9 K referred to feed aperture plane. Benefiting from optimal design and precise mechanical treatment, good scattering performance of OMT and equalized radiation patterns of horn are achieved with an antenna efficiency above 75%.
基金This work is supported by National Key R&D Program of China No.2021YFC2203502 and 2022YFF0711502the National Natural Science Foundation of China(NSFC)(12173077 and 12003062)+5 种基金the Tianshan Innovation Team Plan of Xinjiang Uygur Autonomous Region(2022D14020)the Tianshan Talent Project of Xinjiang Uygur Autonomous Region(2022TSYCCX0095)the Scientific Instrument Developing Project of the Chinese Academy of Sciences,Grant No.PTYQ2022YZZD01China National Astronomical Data Center(NADC)the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China(MOF)and administrated by the Chinese Academy of Sciences(CAS)Natural Science Foundation of Xinjiang Uygur Autonomous Region(2022D01A360).
文摘Artificial Intelligence(AI)is an interdisciplinary research field with widespread applications.It aims at developing theoretical,methodological,technological,and applied systems that simulate,enhance,and assist human intelligence.Recently,notable accomplishments of artificial intelligence technology have been achieved in astronomical data processing,establishing this technology as central to numerous astronomical research areas such as radio astronomy,stellar and galactic(Milky Way)studies,exoplanets surveys,cosmology,and solar physics.This article systematically reviews representative applications of artificial intelligence technology to astronomical data processing,with comprehensive description of specific cases:pulsar candidate identification,fast radio burst detection,gravitational wave detection,spectral classification,and radio frequency interference mitigation.Furthermore,it discusses possible future applications to provide perspectives for astronomical research in the artificial intelligence era.
基金the science research grants from the China Manned Space Project with Nos.CMS-CSST-2021-A01 and CMS-CSST-2021-B05the funding and technical support from the Jiangsu Key Laboratory of Big Data Security and Intelligent Processing。
文摘Astronomical outliers,such as unusual,rare or unknown types of astronomical objects or phenomena,constantly lead to the discovery of genuinely unforeseen knowledge in astronomy.More unpredictable outliers will be uncovered in principle with the increment of the coverage and quality of upcoming survey data.However,it is a severe challenge to mine rare and unexpected targets from enormous data with human inspection due to a significant workload.Supervised learning is also unsuitable for this purpose because designing proper training sets for unanticipated signals is unworkable.Motivated by these challenges,we adopt unsupervised machine learning approaches to identify outliers in the data of galaxy images to explore the paths for detecting astronomical outliers.For comparison,we construct three methods,which are built upon the k-nearest neighbors(KNN),Convolutional Auto-Encoder(CAE)+KNN,and CAE+KNN+Attention Mechanism(att CAE_KNN)separately.Testing sets are created based on the Galaxy Zoo image data published online to evaluate the performance of the above methods.Results show that att CAE_KNN achieves the best recall(78%),which is 53%higher than the classical KNN method and 22%higher than CAE+KNN.The efficiency of att CAE_KNN(10 minutes)is also superior to KNN(4 h)and equal to CAE+KNN(10 minutes)for accomplishing the same task.Thus,we believe that it is feasible to detect astronomical outliers in the data of galaxy images in an unsupervised manner.Next,we will apply att CAE_KNN to available survey data sets to assess its applicability and reliability.
基金funded by the National Key Basic Research Program of China (2014CB845700)the National Natural Science Foundation of China (NSFC, Grant Nos. 61272272, 11178021 and 11033001)NSFC-Texas A&M University Joint Research Program (No. 11411120219)
文摘With the application of advanced astronomical technologies, equipments and methods all over the world, astronomical observations cover the range from radio, infrared, visible light, ultraviolet, X-ray and gamma-ray bands, and enter into the era of full wavelength astronomy. How to effectively integrate data from different ground- and space-based observation equipments, different observers, different bands and different observation times, requires data fusion technology. In this paper we introduce a cross-match tool that is developed in the Python language, is based on the PostgreSQL database and uses Q3C as the core index, facilitating the cross-match work of massive astronomical data. It provides four different cross- match functions, namely： （I） cross-match of the custom error range; （II） cross-match of catalog errors; （III） cross-match based on the elliptic error range; （IV） cross-match of the nearest neighbor algorithm. The resulting cross-matched set provides a good foundation for subsequent data mining and statistics based on multiwavelength data. The most advantageous aspect of this tool is a user-oriented tool applied locally by users. By means of this tool, users can easily create their own databases, manage their own data and cross- match databases according to their requirements. In addition, this tool is also able to transfer data from one database into another database. More importantly, it is easy to get started with the tool and it can be used by astronomers without writing any code.
基金supported by the National Key R&D Program of China(Nos.2021YFC2203502 and 2022YFF0711502)the National Natural Science Foundation of China(NSFC,Nos.12173077 and 12003062)+6 种基金The Tianshan Innovation Team Plan of Xinjiang Uygur Autonomous Region(2022D14020)the Tianshan Talent Project of Xinjiang Uygur Autonomous Region(2022TSYCCX0095)the Scientific Instrument Developing Project of the Chinese Academy of Sciences,Grant No.PTYQ2022YZZD01China National Astronomical Data Center(NADC)the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China(MOF)administrated by the Chinese Academy of Sciences(CAS)Natural Science Foundation of Xinjiang Uygur Autonomous Region(2022D01A360)。
文摘Digital channelization decomposes a wideband signal into multiple adjacent sub-bands using Parallel Technology.Channelization can effectively reduce the pressure on the radio astronomy digital backends system and make wideband signal processing possible.Aiming at the problems of signal attenuation at sub-band edge,spectral leakage and aliasing encountered in wideband signal channelization,algorithms to reduce the problems are studied.We design a Critically Sampled Polyphase Filter Bank(CS-PFB)based on the Finite Impulse Response digital filter with a Hamming Window and systematically analyze the frequency response characteristics of the CS-PFB.Based on the channelized structure of the CS-PFB,an Over Sampled Polyphase Filter Bank(OS-PFB)is designed by data reuse,and the filtering frequency response characteristics of CS-PFB and OS-PFB are compared and analyzed.Using the wideband baseband data generated by the CASPSR(Collaboration for Astronomy Signal processing and electronics research Parkes Swinburne Recorder),we implement sub-band division and 16-band output of these data based on the 2×oversampling OS-PFB,and the problem of spectrum inversion in the sub-bands is corrected.After removing 25%of redundant data in the head and tail of each sub-band,we recombine the sub-bands into a wideband.The wideband signal is almost identical to the original observed signal.Therefore,the experimental results show that the OS-PFB can improve the channel response.For the 400 MHz baseband data of J0437-4715,we compare the pulse profile obtained from the original baseband data with the pulse profile obtained after the channelization and recombination.The phase and amplitude information of the pulse profiles are consistent,which verifies the correctness of our channelization algorithm.
基金partly supported by the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China(MOF)and administered by the Chinese Academy of Sciences(CAS)supported by the National Natural Science Foundation of China(Grant Nos.11573054,11703065,11603044 and 11873081)+1 种基金support from a CAS PIFIUK STFC grant ST/R006598/1。
文摘A large ground-based optical/infrared telescope is being planned for a world-class astronomical site in China.The cloud-free night percentage is the primary meteorological consideration for evaluating candidate sites.The data from GMS and NOAA satellites and the MODIS instrument were utilized in this research,covering the period from 1996 to 2015.Our data analysis benefits from overlapping results from different independent teams as well as a uniform analysis of selected sites using GMS+NOAA data.Although significant ground-based monitoring is needed to validate these findings,we identify three different geographical regions with a high percentage of cloud-free conditions(~83%on average),which is slightly lower than at Mauna Kea and Cerro Armazones(~85%on average)and were chosen for the large international projects TMT and ELT respectively.Our study finds evidence that cloud distributions and the seasonal changes affected by the prevailing westerly winds and summer monsoons reduce the cloud cover in areas influenced by the westerlies.This is consistent with the expectations from climate change models and is suggestive that most of the identified sites will have reduced cloud cover in the future.
基金Supported by Beijing Municipal Science and Technology Commission(Z181100002918001)。
文摘The Earth is buffered from the ferocious onslaught of the solar wind by a thin layer of matter known as the atmosphere and geospace.This layer absorbs energy from irradiance and outburst from the Sun,as well as from disasters,transient phenomena and anthropogenic emissions originated from Earth.Through complicated physics,the absorbed energy changes the atmospheric and geospace state and sometimes gets re-released to power extreme events such as space weather.Taking place globally,these complicated processes cannot be understood unless they are studied globally.The Chinese scientists have proposed the International Meridian Circle Program(IMCP)to meet this demand.By operating nearly 1000 instruments encompassing all latitudes along with the 120°E–60°W longitudes,IMCP aims,for the first time,to construct comprehensive 3D data representation of the atmosphere and geospace on a global scale and empower interdisciplinary research to tackle key questions related to Earth’s environment and climate change.
基金Supported by the National Natural Science Foundation of China。
文摘We will introduce the construction and design of a new simultaneous three-channel multicolor CCD photometer.This photometer has been mounted on the 1.2 m telescope at Jilin Astronomical Observatory,and is applied to study space debris,gamma-ray burst afterglows,asteroids and other rapidly variable objects.As one of the ground follow-up telescopes of the Chinese-French Space-based multi-band astronomical Variable Objects Monitor(SVOM)mission,it appears very essential to evaluate the performance of the photometry system of this photometer,which can achieve simultaneous imaging within a field of view of 21’.5×21’.5,21’.5×21’.5 and21’.3×21’.3 in the Sloan Digital Sky Survey(SDSS)g’,r’,i’bands,respectively.Photometric calibrations were carried out by using plenty of SDSS standard stars,and the relationship between the photometric system and the Johnson-Bessel filter system was also studied.The results of the performance evaluation from observing open cluster M67 are presented.
基金partly supported by the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China (MOF) and administered by the Chinese Academy of Sciences (CAS)supported by the National NaturalScience Foundation of China (Grant Nos.11573054,11703065,11603044 and 11873081)HRAJ acknowledges support from a CAS PIFI and UK STFC grant ST/R006598/1。
文摘Based on previous site testing and satellite cloud data,Ali,Daocheng and Muztagh-ata have been selected as candidate sites for the Large Optical/Infrared Telescope(LOT) in China.We present the data collection,processing,management and quality analysis for our site testing based on using similar hardware.We analyze meteorological data,seeing,background light,cloud and precipitable water vapor data from 2017 March 10 to 2019 March 10.We also investigated the relative usefulness of our all-sky camera data in comparison to that from the meteorological TERRA satellite data based on a night-by-night comparison of the correlation and consistency between them.We find a 6% discrepancy arising from a wide range of factors.
基金supported by the Shanghai Science and Technology Innovation Action Plan(grant No.21511104100)the Global Common Challenge Special Project(grant No.018GJHZ2023110GC)the China National Key Basic Research Program(grant No.2012FY120500)。
文摘From the mid-19th century to the end of the 20th century, photographic plates served as the primary detectors for astronomical observations. Astronomical photographic observations in China began in 1901, and over a century, a total of approximately 30,000 astronomical photographic plates were captured. These historical plates play an irreplaceable role in conducting long-term, time-domain astronomical research. To preserve and explore these valuable original astronomical observational data, Shanghai Astronomical Observatory has organized the transportation of plates, taken during nighttime observations from various stations across the country, to the Sheshan Plate Archive for centralized preservation. For the first time, plate information statistics were calculated. On this basis, the plates were cleaned and digitally scanned, and finally digitized images were acquired for 29,314 plates. In this study, using Gaia DR2 as the reference star catalog, astrometric processing was carried out successfully on 15,696 single-exposure plates, including object extraction, stellar identification,and plate model computation. As a result, for long focal length telescopes, such as the 40 cm double-tube refractor telescope, the 1.56 m reflector telescope at Shanghai Astronomical Observatory, and the 1m reflecting telescope at Yunnan Astronomical Observatory, the astrometric accuracy obtained for their plates is approximately 0."1–0."3. The distribution of astrometric accuracy for medium and short focal length telescopes ranges from 0."3 to 1."0. The relevant data of this batch of plates, including digitized images and a stellar catalog of the plates, are archived and released by the National Astronomical Data Center. Users can access and download plate data based on keywords such as station, telescope, observation year, and observed celestial coordinates.
基金funded by the Joint Research Fund in Astronomy under cooperative agreement between the National Natural Science Foundation of China (NSFC)the Chinese Academy of Sciences (Grant Nos. U1631239 and U1831115)+1 种基金the NSFC (Grant No. 11603008)the Fundamental Research Funds for Central Universities to Harbin Engineering University
文摘Transmission efficiency(TE) and focal ratio degradation(FRD) are two important parameters for evaluating the quality of an optical fiber system used for astronomy. Compared to TE, the focal ratio is more easily influenced by external factors, such as bending or stress. Optical cables are widely implemented for multi-object telescopes and integral field units(IFUs). The design and fabrication process of traditional optical cables seldom considers the requirements of astronomical applications. In this paper, we describe a fiber bundle structure as the basic unit for miniaturized high-density FASOT-IFU optical cables,instead of the micro-tube structure in stranded cables. Seven fibers with hexagonal arrangement were accurately positioned by ultraviolet(UV)-curing acrylate to form the bundle. The coating diameter of a fiber is0.125 mm, and the outer diameter of the bundle is 0.58 mm. Compared with the 0.8 mm micro-tube structure of a traditional stranded cable, the outer diameter of the fiber bundle was reduced by 27.5%. Fiber paste was filled into the bundle to reduce stress between the fibers. We tested the output focal ratio(OFR) in95% of the encircled energy(EE95) of the fibers in the bundle under different conditions. With the incident focal ratio F/8, the maximum difference of OFR is 0.6. In particular, when the incident focal ratio is F/5,the maximum difference of OFR is only 0.1. The jacket formed by the UV-curing acrylate can withstand a certain stress of less than 1.38 N mm-1. The fiber bundle can maintain uniform emitting characteristics with a bending radius of 7.5 cm and with tension less than 6 N. The test results show that the structure of the fiber bundle can be used as a basic unit for miniaturized high-density astronomical optical cables.
文摘This work shows details of an evaluation of an observational system comprising a complementary metal-oxidesemiconductor detector, 60 cm telescope and filter complement. The system’s photometric precision and differential photometric precision, and extinction coefficients were assessed through observations of Supersky flat fields, open clusters, standard stars and exoplanets. Photometry was precision achieved at the 0.02 mag level, with differential photometry of 0.004 mag precision. Extinction was found to agree with previous studies conducted at Xinglong Observatory. Ultimately, the results demonstrate this observing system is capable of precision scientific observations with a charge-coupled device across the optical wavelengths.
