Observing GeV gamma-rays is an important goal of the DArk Matter Particle Explorer(DAMPE)for indirect dark matter searching and high energy astrophysics. In this work, we present a set of accurate instrument response ...Observing GeV gamma-rays is an important goal of the DArk Matter Particle Explorer(DAMPE)for indirect dark matter searching and high energy astrophysics. In this work, we present a set of accurate instrument response functions for DAMPE(DmpIRFs) including the effective area, point-spread function and energy dispersion, which are crucial for gamma-ray data analysis based on statistics from simulation data. A dedicated software named DmpST is developed to facilitate the scientific analyses of DAMPE gamma-ray data. Considering the limited number of photons and angular resolution of DAMPE, the maximum likelihood method is adopted in DmpST to better disentangle different source components. The basic mathematics and framework regarding this software are also introduced in this paper.展开更多
The Standards of Fundamental Astronomy(SOFA)is a service provided by the International Astronomical Union that offers algorithms and software for astronomical calculations,which was released in two versions for FORTRA...The Standards of Fundamental Astronomy(SOFA)is a service provided by the International Astronomical Union that offers algorithms and software for astronomical calculations,which was released in two versions for FORTRAN77 and ANSI C,respectively.In this work,we implement the Python package PyMsOfa for SOFA service by three ways:(1)a Python wrapper package based on a foreign function library for Python(ctypes),(2)a Python wrapper package with the foreign function interface for Python calling C code(cffi)and(3)a Python package directly written in pure Python codes from SOFA subroutines.The package PyMsOfa has fully implemented 247 functions of the original SOFA routines released on 2023 October 11.In addition,PyMsOfa is also extensively examined,which is exactly consistent with those test examples given by the original SOFA.This Python package can be suitable to not only the astrometric detection of habitable planets from the Closeby Habitable Exoplanet Survey mission,but also for the frontier themes of black holes and dark matter related to astrometric calculations and other fields.The source codes are available via http://pypi.org/project/PyMsOfa/and https://github.com/CHES2023/PyMsOfa.展开更多
We describe the current plans for a spectroscopic survey of millions of stars in the Milky Way galaxy using the Guo Shou Jing Telescope （GSJT, formerly calledthe Large sky Area Multi-Object fiber Spectroscopic Telesc...We describe the current plans for a spectroscopic survey of millions of stars in the Milky Way galaxy using the Guo Shou Jing Telescope （GSJT, formerly calledthe Large sky Area Multi-Object fiber Spectroscopic Telescope -- LAMOST）. The survey will obtain spectra for 2.5 million stars brighter than r 〈 19 during dark/grey time, and 5 million stars brighter than r 〈 17 or J 〈 16 on nights that are moonlit or have low transparency. The survey will begin in the fall of 2012, and will run for at least four years. The telescope＇s design constrains the optimal declination range for observations to 10~ 〈 di 〈 50~, and site conditions lead to an emphasis on stars in the direction of the Galactic anticenter. The survey is divided into three parts with different target selection strategies： disk, anticenter, and spheroid. The resulting dataset will be used to study the merger history of the Milky Way, the substructure and evolution of the disks, the nature of the first generation of stars through identification of the lowest metallicity stars, and star formation through study of open clusters and OB associations. Detailed design of the LAMOST Experiment for Galactic Understanding and Exploration （LEGUE） survey will be completed in summer 2012, after a review of the results of the pilot survey.展开更多
Based on years of input from the four geodetic techniques （SLR, GPS, VLBI and DORIS）, the strategies of the combination were studied in SHAO to generate a new global terrestrial reference frame as the material reali...Based on years of input from the four geodetic techniques （SLR, GPS, VLBI and DORIS）, the strategies of the combination were studied in SHAO to generate a new global terrestrial reference frame as the material realization of the ITRS defined in IERS Conventions. The main input includes the time series of weekly solutions （or fortnightly for SLR 1983-1993） of observational data for satellite techniques and session-wise normal equations for VLBI. The set of estimated unknowns includes 3- dimensional Cartesian coordinates at the reference epoch 2005.0 of the stations distributed globally and their rates as well as the time series of consistent Earth Orientation Parameters （EOPs） at the same epochs as the input. Besides the final solution, namely SOL-2, generated by using all the inputs before 2015.0 obtained from short-term observation processing, another reference solution, namely SOL- 1, was also computed by using the input before 2009.0 based on the same combination of procedures for the purpose of comparison with ITRF2008 and DTRF2008 and for evaluating the effect of the latest six more years of data on the combined results. The estimated accuracy of the x-component and y-component of the SOL- 1 TRF-origin was better than 0.1 mm at epoch 2005.0 and better than 0.3 mm yr- 1 in time evolution, either compared with ITRF2008 or DTRF2008. However, the z-component of the translation parameters from SOL-1 to ITRF2008 and DTRF2008 were 3.4 mm and -1.0 ram, respectively. It seems that the z-component of the SOL-1 TRF-origin was much closer to the one in DTRF2008 than the one in ITRF2008. The translation parameters from SOL-2 to ITRF2014 were 2.2, -1.8 and 0.9 mm in the x-, y- and z-components respectively with rates smaller than 0.4 mmyr-1. Similarly, the scale factor transformed from SOL-1 to DTRF2008 was much smaller than that to ITRF2008. The scale parameter from SOL-2 to ITRF2014 was -0.31 ppb with a rate lower than 0.01 ppb yr-1. The external precision （WRMS） compared with IERS EOP 08 C04 of the combined EOP series was smaller than 0.06 mas for the polar motions, smaller than 0.01 ms for the UT1-UTC and smaller than 0.02 ms for the LODs. The precision of the EOPs in SOL-2 was slightly higher than that of SOL-1.展开更多
The Five-hundred-meter Aperture Spherical radio Telescope(FAST) will make contributions to studies of Galactic and extragalactic masers. This telescope, with construction finished and now undergoing commissioning, has...The Five-hundred-meter Aperture Spherical radio Telescope(FAST) will make contributions to studies of Galactic and extragalactic masers. This telescope, with construction finished and now undergoing commissioning, has an innovative design that leads to the highest sensitivity of any single dish radio telescope in the world. FAST's potential for OH megamaser research is discussed, including the sky density of masers detectable in surveys. The scientific impact expected from FAST maser studies is also discussed.展开更多
In this work,we explore the mappings from solar images taken in Hα(6563 A)by the Global Oscillation Network Group(GONG)on the ground to those observed in eight different wavelengths(94,131,171,193,211,304,335 and 160...In this work,we explore the mappings from solar images taken in Hα(6563 A)by the Global Oscillation Network Group(GONG)on the ground to those observed in eight different wavelengths(94,131,171,193,211,304,335 and 1600 A)by SDO/AIA in space.Eight mappings are built by training the conditional Generative Adversarial Networks(cGANs)on datasets with 500 paired images,which are[Hα,AIA94],[Hα,AIA131],[Hα,AIA171],[Hα,AIA193],[Hα,AIA211],[Hα,AIA304],[Hα,AIA335]and[Hα,AIA1600].We evaluate the eight trained cGANs models on validation and test datasets with 154-pair images and 327-pair images,respectively.The model generated fake AIA images match the corresponding observed AIA images well on large-scale structures such as large active regions and prominences.But the small-scale flare loops and filament threads are difficult to reconstruct.Four quantitative comparisons are carried out on the validation and test datasets to score the mappings.We find that the model-generated images in 304 and 1600 A match the corresponding observed images best.This exploration suggests that the cGANs are promising methods for mappings between ground-based Ha and space-based EUV/UV images,while some improvements are necessary.展开更多
Three-way spacecraft Doppler tracking is currently widely used and it plays an important role in the control and navigation of deep space missions. Using the theory of three-way Doppler tracking, including possible vi...Three-way spacecraft Doppler tracking is currently widely used and it plays an important role in the control and navigation of deep space missions. Using the theory of three-way Doppler tracking, including possible violations of the local Lorentz invariance （LLI） and the local position invariance （LPI）, we analyze the post-fit residuals of three-way Doppler tracking data of Mars Express. These Doppler observations were carried out from August 7th to 8th in 2009, with an uplink station administered by the European Space Agency at New Norcia in Australia and three downlink stations at Shanghai, Kunming and Urumqi in China. We find that, although these observations impose preliminary bounds on LLI at the level of 10^-2, they are not suitable for testing LPI because of the configuration of these stations and the accuracy of the observations. To our knowledge, this is one of the first attempts in China to apply radio science to the field of fundamental physics.展开更多
We analyze the post-fit residuals of one-way Doppler tracking data from the Mars Express （MEX） spacecraft to test possible violations of local Lorentz invariance （LLI） and local position invariance （LPI）. These ...We analyze the post-fit residuals of one-way Doppler tracking data from the Mars Express （MEX） spacecraft to test possible violations of local Lorentz invariance （LLI） and local position invariance （LPI）. These one-way Doppler observations were carried out on 2011 August 7 for about 20 minutes at Sheshan Station of Shanghai Astronomical Observatory in China. These downlink signals were sent by MEX for telemetry at X-band. Because we are not able to decode the data in the form of teleme- try and separate them from the carrier frequency, this makes the post-fit residuals of the Doppler data degrade to the level of 0.1 m s^-1. Even so, the residuals can still impose upper bounds on LLI and LPI at 10^-1, which is consistent with the prediction based on our analysis of the detectability. Although the upper bounds given by three-way Doppler tracking of MEX are better than those obtained in the present work, one-way Doppler measurements still provide a unique chance to test possible violations of LLI and LPI far from the ground stations.展开更多
Imaging observations of solar X-ray bursts can reveal details of the energy release process and particle acceleration in flares.Most hard X-ray imagers make use of the modulation-based Fourier transform imaging method...Imaging observations of solar X-ray bursts can reveal details of the energy release process and particle acceleration in flares.Most hard X-ray imagers make use of the modulation-based Fourier transform imaging method,an indirect imaging technique that requires algorithms to reconstruct and optimize images.During the last decade,a variety of algorithms have been developed and improved.However,it is difficult to quantitatively evaluate the image quality of different solutions without a true,reference image of observation.How to choose the values of imaging parameters for these algorithms to get the best performance is also an open question.In this study,we present a detailed test of the characteristics of these algorithms,imaging dynamic range and a crucial parameter for the CLEAN method,clean beam width factor(CBWF).We first used SDO/AIA EUV images to compute DEM maps and calculate thermal X-ray maps.Then these realistic sources and several types of simulated sources are used as the ground truth in the imaging simulations for both RHESSI and ASO-S/HXI.The different solutions are evaluated quantitatively by a number of means.The overall results suggest that EM,PIXON,and CLEAN are exceptional methods for sidelobe elimination,producing images with clear source details.Although MEM_GE,MEM_NJIT,VIS_WV and VIS_CS possess fast imaging processes and generate good images,they too possess associated imperfections unique to each method.The two forward fit algorithms,VF and FF,perform differently,and VF appears to be more robust and useful.We also demonstrated the imaging capability of HXI and available HXI algorithms.Furthermore,the effect of CBWF on image quality was investigated,and the optimal settings for both RHESSI and HXI were proposed.展开更多
In the ancient history,Chinese astronomers had made tremendous achievements.They maintained the longest continuous records of all kinds of astronomical phenomena,such as solar eclipses,sunspots,comets and vip stars(...In the ancient history,Chinese astronomers had made tremendous achievements.They maintained the longest continuous records of all kinds of astronomical phenomena,such as solar eclipses,sunspots,comets and vip stars(nova or supernova),which are still useful today for astronomical research.Ancient展开更多
The proposed design of a microwave superconducting kinetic inductance detector(MKID)array readout system characterizes the performance of MKIDs through a digital homodyne frequency mixing architecture.Meanwhile,the re...The proposed design of a microwave superconducting kinetic inductance detector(MKID)array readout system characterizes the performance of MKIDs through a digital homodyne frequency mixing architecture.Meanwhile,the readout system is implemented using a frequency division multiplexing circuit system,coupled with an FFT design to enable the readout of MKID arrays.The system is characterized by its compact size,low cost,portability,and ease of further development.Together,these features have significant implications for the design and readout of terahertz MKID arrays,while simultaneously advancing both the theoretical and practical aspects of MKID technology.展开更多
Vast magnetospheric regions are mapped along the field lines to the narrow latitudinal band of the polar/auroral regions. Therefore monitoring of solar wind energy dissipation into the ionosphere at auroral latitudes ...Vast magnetospheric regions are mapped along the field lines to the narrow latitudinal band of the polar/auroral regions. Therefore monitoring of solar wind energy dissipation into the ionosphere at auroral latitudes gives unique opportunities to study geomagnetic disturbances in their complexity from a relatively well-localized vantage point. Here we introduce and present the current state of a recently proposed science project for coordinated monitoring of high-latitude activity with the EISCAT (European Incoherent Scatter) radar array supported by ground-based magnetometer and optical data and ENA (Energetic Neutral Atom) observation from the CINEMA (Cube-Sat for Ions, Neutrals, Electrons and Magnetic field) satellite system.展开更多
Based on the updated M giant star catalog selected from Large Sky Area Multi-Object Fiber Spectroscopic Telescope DR9,we identify substructures within the integrals-of-motion space through the Friends-of-Friends clust...Based on the updated M giant star catalog selected from Large Sky Area Multi-Object Fiber Spectroscopic Telescope DR9,we identify substructures within the integrals-of-motion space through the Friends-of-Friends clustering algorithm.We obtain members belonging to several known substructures:the Sagittarius stream,Galactic Anticenter Substructure(GASS),Gaia-Enceladus-Sausage(GES),Splash,and the high-αdisk.Furthermore,we also identify two groups which cannot be clearly associated with previously known substructures.Our findings confirm the existence of metal-rich constituents within the GES,representing newly formed stars that originated from the metal-enriched gas delivered during the GES merger event and subsequently evolved.Additionally,this study further expands the sample of GASS,high-αdisk,and Splash stars.Analysis of these metal-rich M giant stars as members of the GES,Splash,and high-αdisk components supports an evolution scenario for the early Milky Way,as proposed by previous studies.In this scenario,stars initially formed in a high-α primordial disk were dynamically heated by the massive accretion event(GES).This process redistributed stellar orbits,creating the Splash population,while the undisturbed portion of the primordial disk persisted as the present-day high-αdisk component.展开更多
This study presents an achievement of laser cooling of alkaline-earth atoms in the Chinese Space Station’s strontium(Sr)atomic space optical clock.The system’s core components,physical unit,optical unit,and electric...This study presents an achievement of laser cooling of alkaline-earth atoms in the Chinese Space Station’s strontium(Sr)atomic space optical clock.The system’s core components,physical unit,optical unit,and electrical unit,have a total volume of 306 L and a total mass of 163.8 kg.These compact and robust units can overcome mechanical vibrations and temperature fluctuations during space launch.The laser sources of the optical unit are composed of diode lasers,and the injection locking of slave lasers is automatically performed by a program.In the experiment,a blue magneto-optical trap of cold atoms was achieved,with the atom numbers estimated to be approximately(1.50±0.13)×10^(6) for 87Sr and(8.00±0.56)×10^(6) for 88Sr.This work establishes a foundation for atomic confinement and high-precision interrogation in space-based optical clocks and expands the frontiers of cold atom physics in microgravity.展开更多
Research on the properties of neutron stars with dark energy is a particularly interesting yet unresolved problem in astrophysics.We analyze the influence of dark energy on the equation of state,the maximum mass,the s...Research on the properties of neutron stars with dark energy is a particularly interesting yet unresolved problem in astrophysics.We analyze the influence of dark energy on the equation of state,the maximum mass,the surface gravitational redshift and the Keplerian frequency for the traditional neutron star and the hyperon star matter within the relativistic mean field theory,using the GM1 and TM1 parameter sets by considering the two flavor symmetries of SU(6)and SU(3)combined with the observations of PSR J1614-2230,PSR J0348+0432,PSR J0030+0451,RX J0720.4-3125,and 1E 1207.4-5209.It is found that the existence of dark energy leads to the softened equations of the state of the traditional neutron star and the hyperon star.The radius of a fixed-mass traditional neutron star(or hyperon star)with dark energy becomes smaller,which leads to increased compactness.The existence of dark energy can also enhance the surface gravitational redshift and the Keplerian frequency of traditional neutron stars and hyperon stars.The growth of the Keplerian frequency may cause the spin rate to speed up,which may provide a possible way to understand and explain the pulsar glitch phenomenon.Specifically,we infer that the mass and the surface gravitational redshift of PSR J1748-2446ad without dark energy for the GM1(TM1)parameter set are 1.141 M_(☉)(1.309 M_(☉))and 0.095(0.105),respectively.The corresponding values for the GM1(TM1)parameter set are 0.901 M_(☉)(1.072M_(☉))and 0.079(0.091)if PSR J1748-2446ad contains dark energy withα=0.05.PSR J1748-2446ad may be a low-mass pulsar with a lower surface gravitational redshift under our selected models.展开更多
The standing waves existing in radio telescope data are primarily due to reflections among the instruments,which significantly impact the spectral quality of the Five-hundred-meter Aperture Spherical radio Telescope(F...The standing waves existing in radio telescope data are primarily due to reflections among the instruments,which significantly impact the spectral quality of the Five-hundred-meter Aperture Spherical radio Telescope(FAST).Eliminating these standing waves for FAST is challenging given the constant changes in their phases and amplitudes.Over a ten-second period,the phases shift by 18°while the amplitudes fluctuate by 6 mK.Thus,we developed the fast Fourier transform(FFT)filter method to eliminate these standing waves for every individual spectrum.The FFT filter can decrease the rms from 3.2 to 1.15 times the theoretical estimate.Compared to other methods such as sine fitting and running median,the FFT filter achieves a median rms of approximately 1.2 times the theoretical expectation and the smallest scatter at 12%.Additionally,the FFT filter method avoids the flux loss issue encountered with some other methods.The FFT is also efficient in detecting harmonic radio frequency interference(RFI).In the FAST data,we identified three distinct types of harmonic RFI,each with amplitudes exceeding 100 mK and intrinsic frequency periods of 8.1,0.5,and 0.37 MHz,respectively.The FFT filter,proven as the most effective method,is integrated into the H I data calibration and imaging pipeline for FAST(HiFAST,https://hifast.readthedocs.io).展开更多
Decameter-hectometric(DH)Type Ⅱ bursts,arising from coronal mass ejection(CME)-driven shock waves,are crucial for understanding solar-terrestrial interactions and space weather forecasting.This study provides a compr...Decameter-hectometric(DH)Type Ⅱ bursts,arising from coronal mass ejection(CME)-driven shock waves,are crucial for understanding solar-terrestrial interactions and space weather forecasting.This study provides a comprehensive statistical analysis of CMEs associated with DH type Ⅱ solar radio bursts during Solar Cycle 24(2009–2019),utilizing data from the Wind/WAVES,Solar TErrestrial RElations Observatory/SWAVES,and Solar and Heliospheric Observatory/LASCO catalogs.Analyzing 180 events,we report key spectral and kinematic properties,including a mean CME speed of(1058±531)km s^(−1) and a mean width of(288.39±99.3),with 62%classified as halo CMEs.About 12%of the total CMEs are accelerated,58%of them are decelerated,and 30%of them are constant.Similarly,CMEs having a speed≤800 km s^(−1) are constant,and those with speed≥800 km s^(−1) are decelerated.DH type Ⅱ bursts displayed a mean starting frequency of(12,169.72±4939)kHz,ending frequency of(2152.69±3022.07)kHz,bandwidth of(10,017±5353)kHz,and an average duration of(345.62±453)minutes.A power-law relationship was established between the drift rate(df/dt)and burst duration(D),characterized by df/dt=2749.07·D^(−0.88),highlighting the inverse dependence of drift rate on burst longevity.This suggests a dynamic interplay between shock parameters and the ambient solar corona.The findings underscore the persistent and robust spectral coverage of CME-driven shocks,offering new insights into their evolution and impact on the heliospheric environment.展开更多
Integrating available instrumental records with meteorite analysis could build a link between meteorite chemical groups and their original parent bodies.However,such comprehensive source region-tracing studies have no...Integrating available instrumental records with meteorite analysis could build a link between meteorite chemical groups and their original parent bodies.However,such comprehensive source region-tracing studies have not been conducted for any meteorite fall events in China.On 2022 December 15 at 09:48 UT,meteoroid Tanxi was recorded by numerous cameras in populous northern Zhejiang.This event offers an opportunity to conduct the first systematic origin-tracing study for a meteorite fall event in China.The Tanxi meteorite was classified as an H6chondrite.This meteoroid entered the atmosphere with a velocity of 13.49 km s^(-1)and a slope of 69.52°.It most likely underwent a two-stage fragmentation process,with early fragmentation under a dynamic pressure of0.08 MPa,and main fragmentation under a dynamic pressure of 7.83 MPa.Before colliding with the Earth,the meteoroid’s heliocentric orbit had a semimajor axis of 2.363±0.107 au,an eccentricity of 0.584±0.019 and an inclination of 2.078±0.074°.A backward Dshevolution result of 5000 yr shows Tanxi’s orbit is most similar to a small near-Earth asteroid 2016 WV2.The source region analysis of the Tanxi fall indicates that the H chondrites could originate from two distinct reservoirs:the 3:1J mean motion resonance complex(51.2±3.7%)and the v6secular resonance region(41.6±2.9%).展开更多
Using a semi-analytic approach,we estimate halo spins for a large sample of H I-rich galaxies from the Arecibo Legacy Fast ALFA Survey and examine the correlation between H I mass fractions and halo spins.Our analysis...Using a semi-analytic approach,we estimate halo spins for a large sample of H I-rich galaxies from the Arecibo Legacy Fast ALFA Survey and examine the correlation between H I mass fractions and halo spins.Our analysis reveals a strong correlation between halo spin and the H I-to-stellar mass ratio in both low-mass and massive galaxy samples.This finding suggests a universal formation scenario:higher halo spin reduces angular momentum loss and gas condensation,leading to lower star formation rates and weaker feedback,which in turn help retain gas within dark matter halos.展开更多
We estimate halo spins for H I-rich galaxies in the Arecibo Legacy Fast ALFA survey using a semi-analytic approach,examining the relationship between halo spin and stellar surface density.Our findings reveal an invers...We estimate halo spins for H I-rich galaxies in the Arecibo Legacy Fast ALFA survey using a semi-analytic approach,examining the relationship between halo spin and stellar surface density.Our findings reveal an inverse correlation in both low-and high-mass galaxy samples,with stellar surface density decreasing as halo spin increases.This trend highlights the pivotal role of halo spin in galaxy evolution and suggests a universal formation scenario:high-spin halos,accompanied by high-spin accreted gas,retain angular momentum,preventing gas from efficiently condensing in the galactic center and thus suppressing star formation.Consequently,weak feedback redistributes gas to the halo outskirts without significant expulsion.The shallower central gravitational potential in high-spin halos promotes outward stellar migration,leading to more extended stellar distributions and lower stellar surface densities.展开更多
基金supported in part by the National Key Program for Research and Development (2016YFA0400200)the Strategic Priority Research Program of Chinese Academy of Sciences (XDB23040000)+3 种基金the 13th Five-year Informatization Plan of Chinese Academy of Sciences (XXH13506)the National Natural Science Foundation of China (Nos. U1631111, U1738123, U1738136 and U1738210)Youth Innovation Promotion Association of Chinese Academy of Sciencesthe Young Elite Scientists Sponsorship Program
文摘Observing GeV gamma-rays is an important goal of the DArk Matter Particle Explorer(DAMPE)for indirect dark matter searching and high energy astrophysics. In this work, we present a set of accurate instrument response functions for DAMPE(DmpIRFs) including the effective area, point-spread function and energy dispersion, which are crucial for gamma-ray data analysis based on statistics from simulation data. A dedicated software named DmpST is developed to facilitate the scientific analyses of DAMPE gamma-ray data. Considering the limited number of photons and angular resolution of DAMPE, the maximum likelihood method is adopted in DmpST to better disentangle different source components. The basic mathematics and framework regarding this software are also introduced in this paper.
基金financially supported by the National Natural Science Foundation of China(NSFC,Grant Nos.12033010,11773081,12111530175)the Strategic Priority Research Program on Space Science of the Chinese Academy of Sciences(grant No.XDA 15020800)the Foundation of Minor Planets of the Purple Mountain Observatory。
文摘The Standards of Fundamental Astronomy(SOFA)is a service provided by the International Astronomical Union that offers algorithms and software for astronomical calculations,which was released in two versions for FORTRAN77 and ANSI C,respectively.In this work,we implement the Python package PyMsOfa for SOFA service by three ways:(1)a Python wrapper package based on a foreign function library for Python(ctypes),(2)a Python wrapper package with the foreign function interface for Python calling C code(cffi)and(3)a Python package directly written in pure Python codes from SOFA subroutines.The package PyMsOfa has fully implemented 247 functions of the original SOFA routines released on 2023 October 11.In addition,PyMsOfa is also extensively examined,which is exactly consistent with those test examples given by the original SOFA.This Python package can be suitable to not only the astrometric detection of habitable planets from the Closeby Habitable Exoplanet Survey mission,but also for the frontier themes of black holes and dark matter related to astrometric calculations and other fields.The source codes are available via http://pypi.org/project/PyMsOfa/and https://github.com/CHES2023/PyMsOfa.
基金partially supported by the National Natural Science Foundation of China (Grant Nos. 10573022, 10973015, 11061120454and 11243003)the US National Science Foundation through grant AST-09-37523
文摘We describe the current plans for a spectroscopic survey of millions of stars in the Milky Way galaxy using the Guo Shou Jing Telescope （GSJT, formerly calledthe Large sky Area Multi-Object fiber Spectroscopic Telescope -- LAMOST）. The survey will obtain spectra for 2.5 million stars brighter than r 〈 19 during dark/grey time, and 5 million stars brighter than r 〈 17 or J 〈 16 on nights that are moonlit or have low transparency. The survey will begin in the fall of 2012, and will run for at least four years. The telescope＇s design constrains the optimal declination range for observations to 10~ 〈 di 〈 50~, and site conditions lead to an emphasis on stars in the direction of the Galactic anticenter. The survey is divided into three parts with different target selection strategies： disk, anticenter, and spheroid. The resulting dataset will be used to study the merger history of the Milky Way, the substructure and evolution of the disks, the nature of the first generation of stars through identification of the lowest metallicity stars, and star formation through study of open clusters and OB associations. Detailed design of the LAMOST Experiment for Galactic Understanding and Exploration （LEGUE） survey will be completed in summer 2012, after a review of the results of the pilot survey.
基金supported by the Ministry of Science and Technology of China(2015FY310200)the National Key Research and Development Program of China(2016YFB0501405)+1 种基金the National Natural Science Foundation of China(11173048 and 11403076)the State Key Laboratory of Aerospace Dynamics and the Crustal Movement Observation Network of China(CMONOC)
文摘Based on years of input from the four geodetic techniques （SLR, GPS, VLBI and DORIS）, the strategies of the combination were studied in SHAO to generate a new global terrestrial reference frame as the material realization of the ITRS defined in IERS Conventions. The main input includes the time series of weekly solutions （or fortnightly for SLR 1983-1993） of observational data for satellite techniques and session-wise normal equations for VLBI. The set of estimated unknowns includes 3- dimensional Cartesian coordinates at the reference epoch 2005.0 of the stations distributed globally and their rates as well as the time series of consistent Earth Orientation Parameters （EOPs） at the same epochs as the input. Besides the final solution, namely SOL-2, generated by using all the inputs before 2015.0 obtained from short-term observation processing, another reference solution, namely SOL- 1, was also computed by using the input before 2009.0 based on the same combination of procedures for the purpose of comparison with ITRF2008 and DTRF2008 and for evaluating the effect of the latest six more years of data on the combined results. The estimated accuracy of the x-component and y-component of the SOL- 1 TRF-origin was better than 0.1 mm at epoch 2005.0 and better than 0.3 mm yr- 1 in time evolution, either compared with ITRF2008 or DTRF2008. However, the z-component of the translation parameters from SOL-1 to ITRF2008 and DTRF2008 were 3.4 mm and -1.0 ram, respectively. It seems that the z-component of the SOL-1 TRF-origin was much closer to the one in DTRF2008 than the one in ITRF2008. The translation parameters from SOL-2 to ITRF2014 were 2.2, -1.8 and 0.9 mm in the x-, y- and z-components respectively with rates smaller than 0.4 mmyr-1. Similarly, the scale factor transformed from SOL-1 to DTRF2008 was much smaller than that to ITRF2008. The scale parameter from SOL-2 to ITRF2014 was -0.31 ppb with a rate lower than 0.01 ppb yr-1. The external precision （WRMS） compared with IERS EOP 08 C04 of the combined EOP series was smaller than 0.06 mas for the polar motions, smaller than 0.01 ms for the UT1-UTC and smaller than 0.02 ms for the LODs. The precision of the EOPs in SOL-2 was slightly higher than that of SOL-1.
基金supported by the China Ministry of Science and Technology under the National Basic Research Program of China (973 program, 2012CB821800)the National Natural Science Foundation of China (Nos. 11473007, 11373038 and 11590782)supported by the Strategic Priority Research Program (No. XDB09000000) from the Chinese Academy of Sciences
文摘The Five-hundred-meter Aperture Spherical radio Telescope(FAST) will make contributions to studies of Galactic and extragalactic masers. This telescope, with construction finished and now undergoing commissioning, has an innovative design that leads to the highest sensitivity of any single dish radio telescope in the world. FAST's potential for OH megamaser research is discussed, including the sky density of masers detectable in surveys. The scientific impact expected from FAST maser studies is also discussed.
基金financial support from the National Oceanic and Atmospheric Administrationthe National Aeronautics and Space Administration+2 种基金the United States Air Forcesupported by the National Natural Science Foundation of China(Grant Nos.41761134088,11790302(11790300),11473071 and U1731241)the Strategic Priority Research Program on Space Science,CAS(Grant Nos.XDA15052200 and XDA15320301)supported by Scientific Research Project of‘333 Project’of Jiangsu(BRA2019310)。
文摘In this work,we explore the mappings from solar images taken in Hα(6563 A)by the Global Oscillation Network Group(GONG)on the ground to those observed in eight different wavelengths(94,131,171,193,211,304,335 and 1600 A)by SDO/AIA in space.Eight mappings are built by training the conditional Generative Adversarial Networks(cGANs)on datasets with 500 paired images,which are[Hα,AIA94],[Hα,AIA131],[Hα,AIA171],[Hα,AIA193],[Hα,AIA211],[Hα,AIA304],[Hα,AIA335]and[Hα,AIA1600].We evaluate the eight trained cGANs models on validation and test datasets with 154-pair images and 327-pair images,respectively.The model generated fake AIA images match the corresponding observed AIA images well on large-scale structures such as large active regions and prominences.But the small-scale flare loops and filament threads are difficult to reconstruct.Four quantitative comparisons are carried out on the validation and test datasets to score the mappings.We find that the model-generated images in 304 and 1600 A match the corresponding observed images best.This exploration suggests that the cGANs are promising methods for mappings between ground-based Ha and space-based EUV/UV images,while some improvements are necessary.
基金Supported by the National Natural Science Foundation of China
文摘Three-way spacecraft Doppler tracking is currently widely used and it plays an important role in the control and navigation of deep space missions. Using the theory of three-way Doppler tracking, including possible violations of the local Lorentz invariance （LLI） and the local position invariance （LPI）, we analyze the post-fit residuals of three-way Doppler tracking data of Mars Express. These Doppler observations were carried out from August 7th to 8th in 2009, with an uplink station administered by the European Space Agency at New Norcia in Australia and three downlink stations at Shanghai, Kunming and Urumqi in China. We find that, although these observations impose preliminary bounds on LLI at the level of 10^-2, they are not suitable for testing LPI because of the configuration of these stations and the accuracy of the observations. To our knowledge, this is one of the first attempts in China to apply radio science to the field of fundamental physics.
基金funded by the National Natural Science Foundation of China(Grant Nos.11103010,11573015 and 11073047)the Fundamental Research Program of Jiangsu Province of China under No.BK2011553+2 种基金the Research Fund for the Doctoral Program of Higher Education of China(No.20110091120003)the Fundamental Research Funds for the Central Universities(Grant No.20620140586)the Opening Project of Shanghai Key Laboratory of Space Navigation and Position Techniques(Grant No.14DZ2276100)
文摘We analyze the post-fit residuals of one-way Doppler tracking data from the Mars Express （MEX） spacecraft to test possible violations of local Lorentz invariance （LLI） and local position invariance （LPI）. These one-way Doppler observations were carried out on 2011 August 7 for about 20 minutes at Sheshan Station of Shanghai Astronomical Observatory in China. These downlink signals were sent by MEX for telemetry at X-band. Because we are not able to decode the data in the form of teleme- try and separate them from the carrier frequency, this makes the post-fit residuals of the Doppler data degrade to the level of 0.1 m s^-1. Even so, the residuals can still impose upper bounds on LLI and LPI at 10^-1, which is consistent with the prediction based on our analysis of the detectability. Although the upper bounds given by three-way Doppler tracking of MEX are better than those obtained in the present work, one-way Doppler measurements still provide a unique chance to test possible violations of LLI and LPI far from the ground stations.
基金supported by the National Key R&D Program of China 2022YFF0503002the National Natural Science Foundation of China(NSFC,Grant Nos.12333010 and 12233012)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(grant No.XDB0560000)supported by the Prominent Postdoctoral Project of Jiangsu Province(2023ZB304)supported by the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences,grant No.XDA15320000.
文摘Imaging observations of solar X-ray bursts can reveal details of the energy release process and particle acceleration in flares.Most hard X-ray imagers make use of the modulation-based Fourier transform imaging method,an indirect imaging technique that requires algorithms to reconstruct and optimize images.During the last decade,a variety of algorithms have been developed and improved.However,it is difficult to quantitatively evaluate the image quality of different solutions without a true,reference image of observation.How to choose the values of imaging parameters for these algorithms to get the best performance is also an open question.In this study,we present a detailed test of the characteristics of these algorithms,imaging dynamic range and a crucial parameter for the CLEAN method,clean beam width factor(CBWF).We first used SDO/AIA EUV images to compute DEM maps and calculate thermal X-ray maps.Then these realistic sources and several types of simulated sources are used as the ground truth in the imaging simulations for both RHESSI and ASO-S/HXI.The different solutions are evaluated quantitatively by a number of means.The overall results suggest that EM,PIXON,and CLEAN are exceptional methods for sidelobe elimination,producing images with clear source details.Although MEM_GE,MEM_NJIT,VIS_WV and VIS_CS possess fast imaging processes and generate good images,they too possess associated imperfections unique to each method.The two forward fit algorithms,VF and FF,perform differently,and VF appears to be more robust and useful.We also demonstrated the imaging capability of HXI and available HXI algorithms.Furthermore,the effect of CBWF on image quality was investigated,and the optimal settings for both RHESSI and HXI were proposed.
文摘In the ancient history,Chinese astronomers had made tremendous achievements.They maintained the longest continuous records of all kinds of astronomical phenomena,such as solar eclipses,sunspots,comets and vip stars(nova or supernova),which are still useful today for astronomical research.Ancient
基金funded by the National Key Research and Development Program of China under Nos.2023YFA1608200&2020YFC2201703the National Natural Science Foundation of China(NSFC,Grant No.12020101002)the Natural Science Foundation of China for the youth under No.12103093。
文摘The proposed design of a microwave superconducting kinetic inductance detector(MKID)array readout system characterizes the performance of MKIDs through a digital homodyne frequency mixing architecture.Meanwhile,the readout system is implemented using a frequency division multiplexing circuit system,coupled with an FFT design to enable the readout of MKID arrays.The system is characterized by its compact size,low cost,portability,and ease of further development.Together,these features have significant implications for the design and readout of terahertz MKID arrays,while simultaneously advancing both the theoretical and practical aspects of MKID technology.
基金supported by the BK21 Plus program through the National Research Foundation(NRF)funded by the Ministry of Education of Korea.
文摘Vast magnetospheric regions are mapped along the field lines to the narrow latitudinal band of the polar/auroral regions. Therefore monitoring of solar wind energy dissipation into the ionosphere at auroral latitudes gives unique opportunities to study geomagnetic disturbances in their complexity from a relatively well-localized vantage point. Here we introduce and present the current state of a recently proposed science project for coordinated monitoring of high-latitude activity with the EISCAT (European Incoherent Scatter) radar array supported by ground-based magnetometer and optical data and ENA (Energetic Neutral Atom) observation from the CINEMA (Cube-Sat for Ions, Neutrals, Electrons and Magnetic field) satellite system.
基金supported by the National Key Research and Development Program of China No.2024YFA1611902the National Natural Science Foundation of China(NSFC)under grants Nos.12273027 and 12588202+3 种基金the Innovation Team Funds of China West Normal University under grant No.KCXTD2022-6CAS Project for Young Scientists in Basic Research under grants Nos.YSBR-062 and YSBR-092the Strategic Priority Research Program of Chinese Academy of Sciences under grant No.XDB1160102the science research grant from the China Manned Space Project with No.CMS-CSST-2025-A11.
文摘Based on the updated M giant star catalog selected from Large Sky Area Multi-Object Fiber Spectroscopic Telescope DR9,we identify substructures within the integrals-of-motion space through the Friends-of-Friends clustering algorithm.We obtain members belonging to several known substructures:the Sagittarius stream,Galactic Anticenter Substructure(GASS),Gaia-Enceladus-Sausage(GES),Splash,and the high-αdisk.Furthermore,we also identify two groups which cannot be clearly associated with previously known substructures.Our findings confirm the existence of metal-rich constituents within the GES,representing newly formed stars that originated from the metal-enriched gas delivered during the GES merger event and subsequently evolved.Additionally,this study further expands the sample of GASS,high-αdisk,and Splash stars.Analysis of these metal-rich M giant stars as members of the GES,Splash,and high-αdisk components supports an evolution scenario for the early Milky Way,as proposed by previous studies.In this scenario,stars initially formed in a high-α primordial disk were dynamically heated by the massive accretion event(GES).This process redistributed stellar orbits,creating the Splash population,while the undisturbed portion of the primordial disk persisted as the present-day high-αdisk component.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB35010202)the National Natural Science Foundation of China(Grants No.62275268)。
文摘This study presents an achievement of laser cooling of alkaline-earth atoms in the Chinese Space Station’s strontium(Sr)atomic space optical clock.The system’s core components,physical unit,optical unit,and electrical unit,have a total volume of 306 L and a total mass of 163.8 kg.These compact and robust units can overcome mechanical vibrations and temperature fluctuations during space launch.The laser sources of the optical unit are composed of diode lasers,and the injection locking of slave lasers is automatically performed by a program.In the experiment,a blue magneto-optical trap of cold atoms was achieved,with the atom numbers estimated to be approximately(1.50±0.13)×10^(6) for 87Sr and(8.00±0.56)×10^(6) for 88Sr.This work establishes a foundation for atomic confinement and high-precision interrogation in space-based optical clocks and expands the frontiers of cold atom physics in microgravity.
基金partially funded by the Horizontal Scientific Research Project of the National Astronomical Observatories of CAS(Grant No.E0900501)and the Theoretical Fundamental Research Special Project of the Changchun Observatory,National Astronomical Observatories,CAS(Grant No.Y990000205)。
文摘Research on the properties of neutron stars with dark energy is a particularly interesting yet unresolved problem in astrophysics.We analyze the influence of dark energy on the equation of state,the maximum mass,the surface gravitational redshift and the Keplerian frequency for the traditional neutron star and the hyperon star matter within the relativistic mean field theory,using the GM1 and TM1 parameter sets by considering the two flavor symmetries of SU(6)and SU(3)combined with the observations of PSR J1614-2230,PSR J0348+0432,PSR J0030+0451,RX J0720.4-3125,and 1E 1207.4-5209.It is found that the existence of dark energy leads to the softened equations of the state of the traditional neutron star and the hyperon star.The radius of a fixed-mass traditional neutron star(or hyperon star)with dark energy becomes smaller,which leads to increased compactness.The existence of dark energy can also enhance the surface gravitational redshift and the Keplerian frequency of traditional neutron stars and hyperon stars.The growth of the Keplerian frequency may cause the spin rate to speed up,which may provide a possible way to understand and explain the pulsar glitch phenomenon.Specifically,we infer that the mass and the surface gravitational redshift of PSR J1748-2446ad without dark energy for the GM1(TM1)parameter set are 1.141 M_(☉)(1.309 M_(☉))and 0.095(0.105),respectively.The corresponding values for the GM1(TM1)parameter set are 0.901 M_(☉)(1.072M_(☉))and 0.079(0.091)if PSR J1748-2446ad contains dark energy withα=0.05.PSR J1748-2446ad may be a low-mass pulsar with a lower surface gravitational redshift under our selected models.
基金supported by the China National Key Program for Science and Technology Research and Development of China (2022YFA1602901,2023YFA1608204)the National SKA Program of China (No.2022SKA0110201)+5 种基金the National Natural Science Foundation of China (NSFC,grant Nos.11873051,11988101,12033008,12041305,12125302,12173016,and 12203065)the CAS Project for Young Scientists in Basic Research grant (No.YSBR-062)the K.C.Wong Education Foundationthe science research grants from the China Manned Space Projectsupport from the Cultivation Project for FAST Scientific Payoff and Research Achievement of CAMS-CASsupported by the China Postdoctoral Science Foundation grant No.2024M763213
文摘The standing waves existing in radio telescope data are primarily due to reflections among the instruments,which significantly impact the spectral quality of the Five-hundred-meter Aperture Spherical radio Telescope(FAST).Eliminating these standing waves for FAST is challenging given the constant changes in their phases and amplitudes.Over a ten-second period,the phases shift by 18°while the amplitudes fluctuate by 6 mK.Thus,we developed the fast Fourier transform(FFT)filter method to eliminate these standing waves for every individual spectrum.The FFT filter can decrease the rms from 3.2 to 1.15 times the theoretical estimate.Compared to other methods such as sine fitting and running median,the FFT filter achieves a median rms of approximately 1.2 times the theoretical expectation and the smallest scatter at 12%.Additionally,the FFT filter method avoids the flux loss issue encountered with some other methods.The FFT is also efficient in detecting harmonic radio frequency interference(RFI).In the FAST data,we identified three distinct types of harmonic RFI,each with amplitudes exceeding 100 mK and intrinsic frequency periods of 8.1,0.5,and 0.37 MHz,respectively.The FFT filter,proven as the most effective method,is integrated into the H I data calibration and imaging pipeline for FAST(HiFAST,https://hifast.readthedocs.io).
基金supported by the National Key R&D Program of China(2021YFA1600500 and 2021YFA1600503)sponsored by the CAS-TWAS President Fellowship Programpartially supported by the Tianchi Talent Program of the Xinjiang Uygur Autonomous Region of China.
文摘Decameter-hectometric(DH)Type Ⅱ bursts,arising from coronal mass ejection(CME)-driven shock waves,are crucial for understanding solar-terrestrial interactions and space weather forecasting.This study provides a comprehensive statistical analysis of CMEs associated with DH type Ⅱ solar radio bursts during Solar Cycle 24(2009–2019),utilizing data from the Wind/WAVES,Solar TErrestrial RElations Observatory/SWAVES,and Solar and Heliospheric Observatory/LASCO catalogs.Analyzing 180 events,we report key spectral and kinematic properties,including a mean CME speed of(1058±531)km s^(−1) and a mean width of(288.39±99.3),with 62%classified as halo CMEs.About 12%of the total CMEs are accelerated,58%of them are decelerated,and 30%of them are constant.Similarly,CMEs having a speed≤800 km s^(−1) are constant,and those with speed≥800 km s^(−1) are decelerated.DH type Ⅱ bursts displayed a mean starting frequency of(12,169.72±4939)kHz,ending frequency of(2152.69±3022.07)kHz,bandwidth of(10,017±5353)kHz,and an average duration of(345.62±453)minutes.A power-law relationship was established between the drift rate(df/dt)and burst duration(D),characterized by df/dt=2749.07·D^(−0.88),highlighting the inverse dependence of drift rate on burst longevity.This suggests a dynamic interplay between shock parameters and the ambient solar corona.The findings underscore the persistent and robust spectral coverage of CME-driven shocks,offering new insights into their evolution and impact on the heliospheric environment.
基金supported by the National Key Research and Development Program of China(2023YFE0109900)the B-type Strategic Priority Research Program of Chinese Academy of Sciences(grant No.XDB 41000000)+4 种基金the National Natural Science Foundation of China(grant Nos.42273038,62227901,42073060 and 12150009)Space debris and NEO research project(No.KJSP2020020204)Youth Innovation Promotion Association CAS(2023332)the Science and Technology Project of Qinghai Province(2025-ZJ-T0)the Minor Planet Foundation of China.
文摘Integrating available instrumental records with meteorite analysis could build a link between meteorite chemical groups and their original parent bodies.However,such comprehensive source region-tracing studies have not been conducted for any meteorite fall events in China.On 2022 December 15 at 09:48 UT,meteoroid Tanxi was recorded by numerous cameras in populous northern Zhejiang.This event offers an opportunity to conduct the first systematic origin-tracing study for a meteorite fall event in China.The Tanxi meteorite was classified as an H6chondrite.This meteoroid entered the atmosphere with a velocity of 13.49 km s^(-1)and a slope of 69.52°.It most likely underwent a two-stage fragmentation process,with early fragmentation under a dynamic pressure of0.08 MPa,and main fragmentation under a dynamic pressure of 7.83 MPa.Before colliding with the Earth,the meteoroid’s heliocentric orbit had a semimajor axis of 2.363±0.107 au,an eccentricity of 0.584±0.019 and an inclination of 2.078±0.074°.A backward Dshevolution result of 5000 yr shows Tanxi’s orbit is most similar to a small near-Earth asteroid 2016 WV2.The source region analysis of the Tanxi fall indicates that the H chondrites could originate from two distinct reservoirs:the 3:1J mean motion resonance complex(51.2±3.7%)and the v6secular resonance region(41.6±2.9%).
基金support from the National Natural Science Foundation of China(NSFC)grant 12273037the CAS Pioneer Hundred Talents Program(Category B)+1 种基金the USTC Research Funds of the Double First-Class Initiativesupported by the China Manned Space Program with grant No.CMS-CSST-2025-A06 and CMS-CSST-2025-A08.
文摘Using a semi-analytic approach,we estimate halo spins for a large sample of H I-rich galaxies from the Arecibo Legacy Fast ALFA Survey and examine the correlation between H I mass fractions and halo spins.Our analysis reveals a strong correlation between halo spin and the H I-to-stellar mass ratio in both low-mass and massive galaxy samples.This finding suggests a universal formation scenario:higher halo spin reduces angular momentum loss and gas condensation,leading to lower star formation rates and weaker feedback,which in turn help retain gas within dark matter halos.
基金supports from the CAS Pioneer Hundred Talents Program (Category B)the National Natural Science Foundation of China (NSFC, grant No. 12273037)+2 种基金Funds of the Double First-Class Initiativesupported by the research grants from the China Manned Space Project (the second-stage CSST science projects:“Investigation of small-scale structures in galaxies and forecasting of observations” and “CSST study on specialized galaxies in ultraviolet and multi-band”)supported by the China Postdoctoral Science Foundation grant No. 2024M763213
文摘We estimate halo spins for H I-rich galaxies in the Arecibo Legacy Fast ALFA survey using a semi-analytic approach,examining the relationship between halo spin and stellar surface density.Our findings reveal an inverse correlation in both low-and high-mass galaxy samples,with stellar surface density decreasing as halo spin increases.This trend highlights the pivotal role of halo spin in galaxy evolution and suggests a universal formation scenario:high-spin halos,accompanied by high-spin accreted gas,retain angular momentum,preventing gas from efficiently condensing in the galactic center and thus suppressing star formation.Consequently,weak feedback redistributes gas to the halo outskirts without significant expulsion.The shallower central gravitational potential in high-spin halos promotes outward stellar migration,leading to more extended stellar distributions and lower stellar surface densities.
