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HiFAST:An HIdata calibration and imaging pipeline for FAST

Science China(Physics,Mechanics & Astronomy) 2024年第5期67卷 182-199页

作者： Yingjie Jing Jie Wang Chen Xu Ziming Liu Qingze Chen Tiantian Liang Jinlong Xu Yixian Cao Jing Wang Huijie Hu Chuan-Peng Zhang Qi Guo Liang Gao Mei Ai Hengqian Gan Xuyang Gao jinlin han Ligang Hou Zhipeng Hou Peng Jiang Xu Kong Fujia Li Zerui Liu Li Shao Hengxing Pan Jun Pan Lei Qian Jinghai Sun Ningyu Tang Qingliang Yang Bo Zhang Zhiyu Zhang Ming Zhu National Astronomical Observatories Chinese Academy of SciencesBeijing 100012China Institute for Frontiers in Astronomy and Astrophysics Beijing Normal UniversityBeijing 02206China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China Guizhou Radio Astronomical Observatory Guizhou UniversityGuiyang 55000China Max Planck Institute for Extraterrestrial Physics Garching 85748Germany Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China Institute of Computational Cosmology Department of PhysicsUniversity of DurhamDurham DHI 3LEUK CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Deep Space Exploration Laboratory/Department of Astronomy University of Science and Technology of ChinaHefei 230026China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China Astrophysics Department of PhysicsUniversity of OxfordOxford OX/3RHUK College of Earth Sciences Guilin University of TechnologyGuilin 541004China Department of Physics Anhui Normal UniversityWuhu 241002China School of Astronomy and Space Science Nanjing UniversityNanjing 210023China Key Laboratory of Modern Astronomy and Astrophysics Nanjing UniversityNanjing 20023China

The Five-hundred-meter Aperture Spherical radio Telescope(FAST)has the largest aperture and a 19-beam L-band receiver,making it powerful for investigating the neutral hydrogen atomic gas(HI)in the *** present HiFAST(https://***),a dedicated,modular,and self-contained calibration and imaging pipeline for processing the H?data of *** pipeline consists of frequency-dependent noise diode calibration,baseline fitting,standing wave removal using an FFT-based method,flux density calibration,stray radiation correction,and gridding to produce data *** modules can be combined as needed to process the data from most FAST observation modes:tracking,drift scanning,On-The-Fly mapping,and most of their *** HiFAST,the root-mean-square(RMS)noises of the calibrated spectra from all 19 beams were only slightly(~5%)higher than the theoretical *** results for the extended source M33 and the point sources are consistent with the results from *** moment maps(0,1 and 2)of M33 agree well with the results from the Arecibo Galaxy Environment Survey(AGES)with a fractional difference of less than 10%.For a common sample of 221 sources with signal-to-noise ratio S/N>10 from the Arecibo Legacy Fast ALFA(ALFALFA)survey,the mean value of fractional difference in the integrated flux density,Sint,between the two datasets is approximately 0.005%,with a dispersion of 15.4%.Further checks on the integrated flux density of 23 sources with seven observations indicate that the variance in the flux density of the source with luminous objects(Sint>2.5 Jy km s-1)is less than 5%.Our tests suggest that the FAST telescope,with the efficient,precise,and user-friendly pipeline HiFAST,will yield numerous significant scientific findings in the investigation of the H?in the universe.

关键词： fractional luminous correction

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A new method to analyse pulsar nulling phenomenon

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Science China(Physics,Mechanics & Astronomy) 2014年第8期57卷 1600-1606页

作者： YANG AiYuan han jinlin WANG Na Xinjiang Astronomical Observatory Chinese Academy of Sciences The University of Chinese Academy of Sciences National Astronomical Observatories Chinese Academy of Sciences

Pulsar hulling is a phenomenon of sudden cessation of pulse emission for a number of periods. The nulling fraction was often used to characterize the phenomenon. We propose a new method to analyse pulsar hulling phenomenon, by involving two key parameters, the nulling degree, X, which is defined as the angle in a rectangular coordinates for the numbers of nulling periods and bursting periods, and the nulling scale, N, which is defined as the effective length of the consecutive nulling periods and bursting periods. The nulling degree X can be calculated by tanX = Nnulling/Nbursting and the mean is related to the nulling fraction, while the nulling scale, N, is also a newly defined fundamental parameter which indicates how often the nulling occurs. We determined the distributions ofx and N for 10 pulsars by using the data in literature. We found that the nulling degree X indicates the relative length of nulling to that of bursting, and the nulling scale N is found to be related to the derivative of rotation frequency and hence the loss rate of rotational energy of pulsars. Their deviations reflect the randomness of the nulling process.

关键词： pulsars radio sources radiation mechanisms

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An efficient method to identify galaxy clusters by using SuperCOSMOS,2MASS and WISE data

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Science China(Physics,Mechanics & Astronomy) 2014年第11期57卷 2168-2173页

作者： XU WeiWei WEN ZhongLue han jinlin National Astronomical Observatories Chinese Academy of Sciences University of Chinese Academy of Sciences

The survey data of Wide-field Infrared Survey Explorer(WISE)provide an opportunity for the identification of galaxy *** present an efficient method for detecting galaxy clusters by combining the WISE data with SuperCOSMOS and 2MASS *** performing star-galaxy separation,we calculate the number of companion galaxies around the galaxies with photometric redshifts previously estimated by the SuperCOSMOS,2MASS and WISE data.A scaled richness Rscal 30 is set as a criterion to identify *** a sky area of 275 deg2of the Sloan Digital Sky Survey Stripe 82 region,we identify 302 clusters in the redshift range of 0.1

关键词： infrared galaxy clusters redshifts

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Repeated Compton scattering in a strong magnetic field

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Science China(Physics,Mechanics & Astronomy) 2012年第10期55卷 1931-1937页

作者： WANG PengFei CHOU ChihKang han jinlin National Astronomical Observatories Chinese Academy of SciencesBeijing 100012China

Repeated scatterings of unpolarized photons by non-relativistic electrons in a static and uniform magnetic field are investigated by using the Boltzmann equation with quantum mechanical correction factors for the stimulated scattering *** resulting Kompaneets equation depends explicitly on the electron cyclotron frequency and the incidence angle of the incoming photons relative to the direction of the magnetic *** evolutionary behavior of the photon spectrum and energy density is highly anisotropic with respect to the static external magnetic *** applications of our results to the X-ray emission from compact and massive stellar objects are discussed in detail and those to the interaction of the microwave background radiation with the hot electrons in galactic clusters are discussed briefly.

关键词： electromagnetic waves: magnetospheric propagation X-ray scattering: interactions with matter neutron stars

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Discovery of eight lensing clusters of galaxies

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Science China(Physics,Mechanics & Astronomy) 2014年第9期57卷 1809-1815页

作者： LIANG SuMing WEN ZhongLue han jinlin JIANG YunYing National Astronomical Observatories Chinese Academy of Sciences The University of Chinese Academy of Sciences

Clusters of galaxies have a huge mass which can act as gravitational *** behind clusters can be distorted by the lenses to form arcs in *** a search was done for giant lensed arcs using the SDSS *** visually inspecting SDSS images of newly identified clusters in the SDSS DR8 and Stripe 82 data,we discover 8 strong lensing clusters together with additional 3probable and 6 possible *** lensed arcs show bluer colors than the member galaxies of *** masses and optical luminosities of galaxy clusters interior to the arcs are *** mass-to-light ratios are found to be in the range of a few tens of M⊙/L⊙,consistent with the distribution of previously known lensing clusters.

关键词： galaxy clusters gravitational lenses and luminous arcs photography and photometry

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The best detection conditions for pulsars in the Galactic disk

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Science China(Physics,Mechanics & Astronomy) 2011年第3期54卷 552-557页

作者： XU XiangYang WANG Chen han jinlin HU Lin College of Science Guizhou University Guiyang 550025 China National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China

Radio detection of pulsars in the Galactic disk is strongly affected by the dispersion and scattering effect of the interstellar medium and the Galactic background radio emission. In order to know the best conditions for discovery of pulsars, we select and simulate pulsar samples in the Galactic disk, and calculate the detection probability with various observation conditions (such as observational frequency, telescope aperture, receiver bandwidth and integration time). We have found that the detection fraction increases with the telescope aperture, receiver bandwidth and integration time. To detect pulsars in the nearer half of the Galactic disk, the observation frequency should be in the range of 1-2 GHz, while for pulsars in the farther half of the disk, the frequency should be in the range of 3.5-4.5 GHz. Due to the strong influence of scattering, the short period pulsars are hard to be detected, especially for pulsars in the farther half of the Galactic disk.

关键词： pulsars neutron stars radio telescopes scattering of electromagnetic radiation in plasmas

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Five E+A (post-starburst) galaxies as Brightest Cluster Galaxies

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Science China(Physics,Mechanics & Astronomy) 2012年第2期55卷 354-357页

作者： LIU FengShan WEN ZhongLue han jinlin MENG XianMin College of Physical Science and Technology Shenyang Normal UniversityShenyang 110034China National Astronomical Observatories Chinese Academy of SciencesA20 Datun RoadBeijing 100012China

Brightest Cluster Galaxies （BCGs） are mostly elliptical galaxies and very rarely have prominent star formations. We found that five out of 8,812 BCGs are E＋A （i.e., post-starburst） galaxies, having an Hd absorption line with an equivalent width 〉2.5 A and no distinct emission lines in [O II] and Ha-. The E＋A features we identified from the BCGs for the first time are not as significant as those in general galaxies, indicating that historically the star formations were not very violent.

关键词： galaxies clusters general

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HiFAST:An H?data calibration and imaging pipeline for FAST

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Science China(Physics,Mechanics & Astronomy) 2024年第5期Mechanics & Astronomy) .卷 186-203页

作者： Yingjie Jing Jie Wang Chen Xu Ziming Liu Qingze Chen Tiantian Liang Jinlong Xu Yixian Cao Jing Wang Huijie Hu Chuan-Peng Zhang Qi Guo Liang Gao Mei Ai Hengqian Gan Xuyang Gao jinlin han Ligang Hou Zhipeng Hou Peng Jiang Xu Kong Fujia Li Zerui Liu Li Shao Hengxing Pan Jun Pan Lei Qian Jinghai Sun Ningyu Tang Qingliang Yang Bo Zhang Zhiyu Zhang Ming Zhu National Astronomical Observatories Chinese Academy of Sciences Institute for Frontiers in Astronomy and Astrophysics Beijing Normal University School of Astronomy and Space Science University of Chinese Academy of Sciences Guizhou Radio Astronomical Observatory Guizhou University Max Planck Institute for Extraterrestrial Physics Kavli Institute for Astronomy and Astrophysics Peking University Institute of Computational Cosmology Department of PhysicsUniversity of Durham CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of Sciences Deep Space Exploration Laboratory/Department of Astronomy University of Science and Technology of China School of Astronomy and Space Science University of Science and Technology of China Astrophysics Department of PhysicsUniversity of Oxford College of Earth Sciences Guilin University of Technology Department of Physics Anhui Normal University School of Astronomy and Space Science Nanjing University Key Laboratory of Modern Astronomy and Astrophysics Nanjing University

The Five-hundred-meter Aperture Spherical radio Telescope（FAST） has the largest aperture and a 19-beam L-band receiver,making it powerful for investigating the neutral hydrogen atomic gas（H?） in the *** present HiFAST（https://***）,a dedicated,modular,and self-contained calibration and imaging pipeline for processing the H?data of *** pipeline consists of frequency-dependent noise diode calibration,baseline fitting,standing wave removal using an FFT-based method,flux density calibration,stray radiation correction,and gridding to produce data *** modules can be combined as needed to process the data from most FAST observation modes:tracking,drift scanning,On-The-Fly mapping,and most of their *** HiFAST,the root-mean-square（RMS） noises of the calibrated spectra from all 19 beams were only slightly（～5%） higher than the theoretical *** results for the extended source M33 and the point sources are consistent with the results from *** moment maps（0,1 and 2） of M33 agree well with the results from the Arecibo Galaxy Environment Survey（AGES） with a fractional difference of less than 10%.For a common sample of 221 sources with signal-to-noise ratio S/N>10 from the Arecibo Legacy Fast ALFA（ALFALFA） survey,the mean value of fractional difference in the integrated flux density,Sint,between the two datasets is approximately 0.005%,with a dispersion of 15.4%.Further checks on the integrated flux density of 23 sources with seven observations indicate that the variance in the flux density of the source with luminous objects(Sint>2.5 Jy km s-1) is less than 5%.Our tests suggest that the FAST telescope,with the efficient,precise,and user-friendly pipeline HiFAST,will yield numerous significant scientific findings in the investigation of the H? in the universe.

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时序InSAR技术在水库监测中的应用研究

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水利信息化 2024年第2期 42-46页

作者：郭子琦韩锦琳王媛潘子轩河南省水利勘测有限公司河南郑州450008

针对InSAR变形监测成本低、广域普查的特点,利用Sentinel-1A影像,对洛阳市某水库蓄水初期进行时序InSAR变形监测。经过变形监测将研究区划分为4个滑坡隐患区及4个城镇疑似沉降区,采用遥感普查+重点监测方案,对库区进行拦水坝变形分析、... 详细信息

针对InSAR变形监测成本低、广域普查的特点,利用Sentinel-1A影像,对洛阳市某水库蓄水初期进行时序InSAR变形监测。经过变形监测将研究区划分为4个滑坡隐患区及4个城镇疑似沉降区,采用遥感普查+重点监测方案,对库区进行拦水坝变形分析、地质灾害高发区普查、城镇地表变形监测,最后整体评估水库蓄水工程对城镇地质扰动的影响。结果表明:2020—2021年水库拦水坝中部为形变显著区,2年间最大累计变形为54.1 mm,两侧变形数值呈对称状分布,符合迎水压力结构受力特征;水利工程建设对周边城镇的扰动几乎可以忽略不计,测区内整体呈稳定状态。时序InSAR技术非接触式监测地表地物变形,可为水库巡检预警机制提供新的技术方案。

关键词： InSAR 时序变形监测水库拦水坝地质灾害

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Peering into the Milky Way by FAST:Ⅲ.Magnetic fields in the Galactic halo and farther spiral arms revealed by the Faraday effect of faint pulsars

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Science China(Physics,Mechanics & Astronomy) 2022年第12期65卷 39-54页

作者： Jun Xu jinlin han PengFei Wang Yi Yan National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of Astronomy University of Chinese Academy of SciencesBeijing 100049China

The Five-hundred-meter Aperture Spherical radio Telescope(FAST)is the most sensitive radio telescope for pulsar *** make polarimetric measurements of a large number of faint and distant pulsars using the *** present the new measurements of Faraday rotation for 134 faint pulsars in the Galactic *** improvements are also made for some basic pulsar parameters for 15 of *** analyse the newly determined rotation measures(RMs)for the Galactic magnetic fields by using these 134 halo pulsars,together with previously available RMs for pulsars and extragalactic radio sources and also the newly determined RMs for another 311 faint pulsars which are either newly discovered in the project of the Galactic Plane Pulsar Snapshot(GPPS)survey or previously known pulsars without *** RM tomographic analysis in the first Galactic quadrant gives roughly the same field strength of around 2μG for the large-scale toroidal halo magnetic *** scale height of the halo magnetic fields is found to be at least 2.7±0.3 *** RM differentiation of a large number of pulsars in the Galactic disk in the Galactic longitude range of 26°

关键词： magnetic fields interstellar medium pulsars

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