The Educational Adaptive-optics Solar Telescope(EAST)at the Shanghai Astronomy Museum has been running routine astronomical observations since 2021.It is a 65-cm-aperture Gregorian solar telescope for scientific educa...The Educational Adaptive-optics Solar Telescope(EAST)at the Shanghai Astronomy Museum has been running routine astronomical observations since 2021.It is a 65-cm-aperture Gregorian solar telescope for scientific education,outreach,and research.The telescope system is designed in an“open”format so that the solar tower architecture can be integrated with it,and visitors can watch the observations live from inside the tower.Equipped with adaptive optics,a high-resolution imaging system,and an integral field unit spectro-imaging system,this telescope can obtain high-resolution solar images in the TiO and Hαbands,and perform spectral image reconstruction using 400 optical fibers at selected wavelengths.It can be used not only in public education and scientific outreach but also in solar physics research.展开更多
The science of radio astronomy focuses on the observation and study of celestial objects by reading their radio waves. The 5 meter radio-telescope is able to observe different radio sources using a C-band LNB. This re...The science of radio astronomy focuses on the observation and study of celestial objects by reading their radio waves. The 5 meter radio-telescope is able to observe different radio sources using a C-band LNB. This research was essentially focused on Crab Nebula, also known as Taurus A. The study led to interesting observations, which were validated numerically using various scientific computing software. The radio waves emitted by Taurus A are readable by the RTL-SDR, a software defined radio receiver. This device is capable of reading radio frequencies in the range of 0.5 MHZ to 1700 MHZ.展开更多
Attempts to determine characters of astronomical objects have been one of major and vibrant activities in both astronomy and data science fields.Instead of a manual inspection,various automated systems are invented to...Attempts to determine characters of astronomical objects have been one of major and vibrant activities in both astronomy and data science fields.Instead of a manual inspection,various automated systems are invented to satisfy the need,including the classification of light curve profiles.A specific Kaggle competition,namely Photometric LSST Astronomical Time-Series Classification Challenge(PLAsTiCC),is launched to gather new ideas of tackling the abovementioned task using the data set collected from the Large Synoptic Survey Telescope(LSST)project.Almost all proposed methods fall into the supervised family with a common aim to categorize each object into one of pre-defined types.As this challenge focuses on developing a predictive model that is robust to classifying unseen data,those previous attempts similarly encounter the lack of discriminate features,since distribution of training and actual test datasets are largely different.As a result,well-known classification algorithms prove to be sub-optimal,while more complicated feature extraction techniques may help to slightly boost the predictive performance.Given such a burden,this research is set to explore an unsupervised alternative to the difficult quest,where common classifiers fail to reach the 50%accuracy mark.A clustering technique is exploited to transform the space of training data,from which a more accurate classifier can be built.In addition to a single clustering framework that provides a comparable accuracy to the front runners of supervised learning,a multiple-clustering alternative is also introduced with improved performance.In fact,it is able to yield a higher accuracy rate of 58.32%from 51.36%that is obtained using a simple clustering.For this difficult problem,it is rather good considering for those achieved by well-known models like support vector machine(SVM)with 51.80%and Naive Bayes(NB)with only 2.92%.展开更多
In order to ensure the normal operation of radio astronomy observations,an extremely sensitive receiver system needs to be equipped in front of the large radio telescope.An 8-pole wideband high-temperature superconduc...In order to ensure the normal operation of radio astronomy observations,an extremely sensitive receiver system needs to be equipped in front of the large radio telescope.An 8-pole wideband high-temperature superconducting(HTS)filter using a Coplanar Spiral Resonator Structure with a passband of 1160~1670 MHz is developed to suppress strong radio interference.The filter is fabricated on a 36 mm×14 mm YBCO HTS film,which is deposited on a 0.5 mm thick MgO substrate.The minimum insertion loss measured in the liquid nitrogen temperature region is 0.03 dB,and the first parasitic passband appears at 2600 MHz.The measured results are in good agreement with the simulations.The filter can be used in radio telescope receivers for the observation of neutral hydrogen and pulsars,as well as in high-sensitivity satellite navigation instruments.展开更多
The ESA and CAS SMILE mission orbit is highly elliptical and will pass through multiple radiation environments.The Soft X-ray Imager(SXI)instrument aboard has a radiation shutter door designed to close when the surrou...The ESA and CAS SMILE mission orbit is highly elliptical and will pass through multiple radiation environments.The Soft X-ray Imager(SXI)instrument aboard has a radiation shutter door designed to close when the surrounding radiation flux is high.The shutter door will close when passing below an altitude threshold to protect against trapped particles in the Earth’s Van Allen Belts.Therefore,two radiation environments can be approximated based on the shutter door position:open and closed.The instrument background for the CCDs(Charge-Coupled Devices)that form the focal plane array of the SXI were evaluated for the two environments.Due to the correlation of the space environment with the solar cycle,the solar minima and maxima,the background was also evaluated at these two extremes.The results demonstrated that the highest instrument background will occur during solar minima due to the main contributing source being Galactic Cosmic Rays(GCRs).It was also found that the open background was highest for solar minima and that the closed background was highest during solar maxima.This is due to the radiation shutter door acting as a scattering centre and the changes in the energy flux distribution of the GCRs between the two solar extremes.展开更多
来自人造卫星的信号是射电天文观测面临的主要射频干扰(radio frequency interference,RFI)之一,这些RFI会将天文信号掩埋,为天文信号的搜寻和分析带来困扰。为了缓减卫星对天文观测的影响,我们在之前的工作中为500 m口径球面射电望远镜...来自人造卫星的信号是射电天文观测面临的主要射频干扰(radio frequency interference,RFI)之一,这些RFI会将天文信号掩埋,为天文信号的搜寻和分析带来困扰。为了缓减卫星对天文观测的影响,我们在之前的工作中为500 m口径球面射电望远镜(Five-hundred-meter Aperture Spherical radio Telescope,FAST)开发了卫星电磁干扰监测软件,主要包括卫星数据库、观测模块和监测模块。近年来随着多个巨型卫星星座的规划发射以及望远镜观测模式的增多,卫星对射电天文观测的影响更为复杂,已有的软件已经不能满足实际的需要。为此,本文在单个卫星干扰分析的基础上提出了卫星星座的干扰评估方法,并对已有监测软件进行了升级,升级后卫星数据库覆盖更多的在轨卫星及星座信息且能够自动化更新,观测模块能够支持更多种观测模式下的卫星过境预测和干扰评估。在实际天文观测中,通过接在FAST接收机上的频谱仪数据对软件的干扰预测结果进行了实验验证,结果证明升级后的软件能够在多种观测模式下预测可能威胁的卫星以及对应的过境时间,为望远镜观测规划的调整、卫星干扰的规避和接收系统的保护提供重要的支撑。展开更多
The Jiao Tong University Spectroscopic Telescope(JUST)is a 4.4-meter f/6.0 segmented-mirror telescope dedicated to spectroscopic observations.The JUST primary mirror is composed of 18 hexagonal segments,each with a di...The Jiao Tong University Spectroscopic Telescope(JUST)is a 4.4-meter f/6.0 segmented-mirror telescope dedicated to spectroscopic observations.The JUST primary mirror is composed of 18 hexagonal segments,each with a diameter of 1.1 m.JUST provides two Nasmyth platforms for placing science instruments.One Nasmyth focus fits a field of view of 10′and the other has an extended field of view of 1.2°with correction optics.A tertiary mirror is used to switch between the two Nasmyth foci.JUST will be installed at a site at Lenghu in Qinghai Province,China,and will conduct spectroscopic observations with three types of instruments to explore the dark universe,trace the dynamic universe,and search for exoplanets:(1)a multi-fiber(2000 fibers)medium-resolution spectrometer(R=4000-5000)to spectroscopically map galaxies and large-scale structure;(2)an integral field unit(IFU)array of 500 optical fibers and/or a long-slit spectrograph dedicated to fast follow-ups of transient sources for multi-messenger astronomy;(3)a high-resolution spectrometer(R~100000)designed to identify Jupiter analogs and Earth-like planets,with the capability to characterize the atmospheres of hot exoplanets.展开更多
随着无线电技术的发展,射频干扰(radio frequency interference,RFI)对射电天文观测的影响越来越大,尤其是周期性RFI对天文观测的影响越来越显著。本文围绕宽带、高时间分辨率频谱数据,采用阈值计算、噪声通道过滤、快速傅里叶变换、周...随着无线电技术的发展,射频干扰(radio frequency interference,RFI)对射电天文观测的影响越来越大,尤其是周期性RFI对天文观测的影响越来越显著。本文围绕宽带、高时间分辨率频谱数据,采用阈值计算、噪声通道过滤、快速傅里叶变换、周期计算、通道合并、来源分析和模板库建立等步骤,提出一种面向宽带频谱序列的周期RFI统计方法。将该方法应用于新疆天文台南山观测站26 m射电望远镜(Nan Shan 26 m Radio Telescope,NSRT)脉冲星观测终端数据,有效地检测并提取出了频谱序列中的周期性RFI,可为进一步电磁干扰缓解提供数据支撑。展开更多
基金supported by the Shanghai Municipal People’s Government
文摘The Educational Adaptive-optics Solar Telescope(EAST)at the Shanghai Astronomy Museum has been running routine astronomical observations since 2021.It is a 65-cm-aperture Gregorian solar telescope for scientific education,outreach,and research.The telescope system is designed in an“open”format so that the solar tower architecture can be integrated with it,and visitors can watch the observations live from inside the tower.Equipped with adaptive optics,a high-resolution imaging system,and an integral field unit spectro-imaging system,this telescope can obtain high-resolution solar images in the TiO and Hαbands,and perform spectral image reconstruction using 400 optical fibers at selected wavelengths.It can be used not only in public education and scientific outreach but also in solar physics research.
文摘The science of radio astronomy focuses on the observation and study of celestial objects by reading their radio waves. The 5 meter radio-telescope is able to observe different radio sources using a C-band LNB. This research was essentially focused on Crab Nebula, also known as Taurus A. The study led to interesting observations, which were validated numerically using various scientific computing software. The radio waves emitted by Taurus A are readable by the RTL-SDR, a software defined radio receiver. This device is capable of reading radio frequencies in the range of 0.5 MHZ to 1700 MHZ.
基金funded by the Security BigData Fusion Project(Office of theMinistry of Higher Education,Science,Research and Innovation).The corresponding author is the project PI.
文摘Attempts to determine characters of astronomical objects have been one of major and vibrant activities in both astronomy and data science fields.Instead of a manual inspection,various automated systems are invented to satisfy the need,including the classification of light curve profiles.A specific Kaggle competition,namely Photometric LSST Astronomical Time-Series Classification Challenge(PLAsTiCC),is launched to gather new ideas of tackling the abovementioned task using the data set collected from the Large Synoptic Survey Telescope(LSST)project.Almost all proposed methods fall into the supervised family with a common aim to categorize each object into one of pre-defined types.As this challenge focuses on developing a predictive model that is robust to classifying unseen data,those previous attempts similarly encounter the lack of discriminate features,since distribution of training and actual test datasets are largely different.As a result,well-known classification algorithms prove to be sub-optimal,while more complicated feature extraction techniques may help to slightly boost the predictive performance.Given such a burden,this research is set to explore an unsupervised alternative to the difficult quest,where common classifiers fail to reach the 50%accuracy mark.A clustering technique is exploited to transform the space of training data,from which a more accurate classifier can be built.In addition to a single clustering framework that provides a comparable accuracy to the front runners of supervised learning,a multiple-clustering alternative is also introduced with improved performance.In fact,it is able to yield a higher accuracy rate of 58.32%from 51.36%that is obtained using a simple clustering.For this difficult problem,it is rather good considering for those achieved by well-known models like support vector machine(SVM)with 51.80%and Naive Bayes(NB)with only 2.92%.
基金supported by the Science and Technology Project of Tibet Autonomous under grant XZ201901-GB-21the National Natural Science Foundation of China under grant11073027the Science and Technology Research and Development Program Project of China National Railway Group under grant P2021G011。
文摘In order to ensure the normal operation of radio astronomy observations,an extremely sensitive receiver system needs to be equipped in front of the large radio telescope.An 8-pole wideband high-temperature superconducting(HTS)filter using a Coplanar Spiral Resonator Structure with a passband of 1160~1670 MHz is developed to suppress strong radio interference.The filter is fabricated on a 36 mm×14 mm YBCO HTS film,which is deposited on a 0.5 mm thick MgO substrate.The minimum insertion loss measured in the liquid nitrogen temperature region is 0.03 dB,and the first parasitic passband appears at 2600 MHz.The measured results are in good agreement with the simulations.The filter can be used in radio telescope receivers for the observation of neutral hydrogen and pulsars,as well as in high-sensitivity satellite navigation instruments.
文摘The ESA and CAS SMILE mission orbit is highly elliptical and will pass through multiple radiation environments.The Soft X-ray Imager(SXI)instrument aboard has a radiation shutter door designed to close when the surrounding radiation flux is high.The shutter door will close when passing below an altitude threshold to protect against trapped particles in the Earth’s Van Allen Belts.Therefore,two radiation environments can be approximated based on the shutter door position:open and closed.The instrument background for the CCDs(Charge-Coupled Devices)that form the focal plane array of the SXI were evaluated for the two environments.Due to the correlation of the space environment with the solar cycle,the solar minima and maxima,the background was also evaluated at these two extremes.The results demonstrated that the highest instrument background will occur during solar minima due to the main contributing source being Galactic Cosmic Rays(GCRs).It was also found that the open background was highest for solar minima and that the closed background was highest during solar maxima.This is due to the radiation shutter door acting as a scattering centre and the changes in the energy flux distribution of the GCRs between the two solar extremes.
文摘来自人造卫星的信号是射电天文观测面临的主要射频干扰(radio frequency interference,RFI)之一,这些RFI会将天文信号掩埋,为天文信号的搜寻和分析带来困扰。为了缓减卫星对天文观测的影响,我们在之前的工作中为500 m口径球面射电望远镜(Five-hundred-meter Aperture Spherical radio Telescope,FAST)开发了卫星电磁干扰监测软件,主要包括卫星数据库、观测模块和监测模块。近年来随着多个巨型卫星星座的规划发射以及望远镜观测模式的增多,卫星对射电天文观测的影响更为复杂,已有的软件已经不能满足实际的需要。为此,本文在单个卫星干扰分析的基础上提出了卫星星座的干扰评估方法,并对已有监测软件进行了升级,升级后卫星数据库覆盖更多的在轨卫星及星座信息且能够自动化更新,观测模块能够支持更多种观测模式下的卫星过境预测和干扰评估。在实际天文观测中,通过接在FAST接收机上的频谱仪数据对软件的干扰预测结果进行了实验验证,结果证明升级后的软件能够在多种观测模式下预测可能威胁的卫星以及对应的过境时间,为望远镜观测规划的调整、卫星干扰的规避和接收系统的保护提供重要的支撑。
基金This work is supported by“the Fundamental Research Funds for the Central Universities”,111 project No.B20019Shanghai Natural Science Foundation,grant No.19ZR1466800.
文摘The Jiao Tong University Spectroscopic Telescope(JUST)is a 4.4-meter f/6.0 segmented-mirror telescope dedicated to spectroscopic observations.The JUST primary mirror is composed of 18 hexagonal segments,each with a diameter of 1.1 m.JUST provides two Nasmyth platforms for placing science instruments.One Nasmyth focus fits a field of view of 10′and the other has an extended field of view of 1.2°with correction optics.A tertiary mirror is used to switch between the two Nasmyth foci.JUST will be installed at a site at Lenghu in Qinghai Province,China,and will conduct spectroscopic observations with three types of instruments to explore the dark universe,trace the dynamic universe,and search for exoplanets:(1)a multi-fiber(2000 fibers)medium-resolution spectrometer(R=4000-5000)to spectroscopically map galaxies and large-scale structure;(2)an integral field unit(IFU)array of 500 optical fibers and/or a long-slit spectrograph dedicated to fast follow-ups of transient sources for multi-messenger astronomy;(3)a high-resolution spectrometer(R~100000)designed to identify Jupiter analogs and Earth-like planets,with the capability to characterize the atmospheres of hot exoplanets.
文摘随着无线电技术的发展,射频干扰(radio frequency interference,RFI)对射电天文观测的影响越来越大,尤其是周期性RFI对天文观测的影响越来越显著。本文围绕宽带、高时间分辨率频谱数据,采用阈值计算、噪声通道过滤、快速傅里叶变换、周期计算、通道合并、来源分析和模板库建立等步骤,提出一种面向宽带频谱序列的周期RFI统计方法。将该方法应用于新疆天文台南山观测站26 m射电望远镜(Nan Shan 26 m Radio Telescope,NSRT)脉冲星观测终端数据,有效地检测并提取出了频谱序列中的周期性RFI,可为进一步电磁干扰缓解提供数据支撑。
