Accurate estimation of Zenith Tropospheric Delay(ZTD)is essential for mitigating atmospheric effects in radio astronomical observations and improving the retrieval of precipitable water vapor(PWV).In this study,we fir...Accurate estimation of Zenith Tropospheric Delay(ZTD)is essential for mitigating atmospheric effects in radio astronomical observations and improving the retrieval of precipitable water vapor(PWV).In this study,we first analyze the periodic characteristics of ZTD at the NanShan Radio Telescope site using Fourier transform,revealing its dominant seasonal variations,and then investigate the correlation between ZTD and local meteorological parameters,to better understand atmospheric influences on tropospheric delay.Based on these analyses,we propose a hybrid deep learning Gated Recurrent Units-Long Short-Term Memory model,incorporating meteorological parameters as external inputs to enhance ZTD forecasting accuracy.Experimental results demonstrate that the proposed approach achieves a Root Mean Squared Error of 7.97 mm and a correlation coefficient R of 96%,significantly outperforming traditional empirical models and standalone deep learning architectures.These findings indicate that the model effectively captures both short-term dynamics and long-term dependencies in ZTD variations.The improved ZTD predictions not only contribute to reducing atmospheric errors in radio astronomical observations but also provide a more reliable basis for PWV retrieval and forecasting.This study highlights the potential of deep learning in tropospheric delay modeling,offering advancements in both atmospheric science and geodetic applications.展开更多
The importance of Very Long Baseline Interferometry(VLBI)for pulsar research is becoming increasingly prominent and receiving more and more attention.We present the pathfinding pulsar observation results with the Chin...The importance of Very Long Baseline Interferometry(VLBI)for pulsar research is becoming increasingly prominent and receiving more and more attention.We present the pathfinding pulsar observation results with the Chinese VLBI Network(CVN)incorporating the Five-hundred-meter Aperture Spherical radio Telescope(FAST).On MJD 60045(11th April 2023),PSRs B0919+06 and B1133+16 were observed with the phase-referencing mode in the L-band using four radio telescopes(FAST,TianMa,Haoping,and Nanshan)and correlated with the pulsar binning mode of the distributed FX-style software correlator in Shanghai.After further data processing with the NRAO Astronomical Image Processing System(AIPS),we detected these two pulsars and fitted their current positions with accuracy at the milliarcsecond level.By comparison,our results show significantly better agreement with predicted values based on historical VLBI observations than those with previous timing observations,as pulsar astrometry with the VLBI provides a more direct and model-independent method for accurately obtaining related parameters.展开更多
The East Asian Very Long Baseline Interferometry(VLBI) Network(EAVN) is a rapidly evolving international VLBI array that is currently promoted under joint efforts among China,Japan and Korea.EAVN aims at forming a joi...The East Asian Very Long Baseline Interferometry(VLBI) Network(EAVN) is a rapidly evolving international VLBI array that is currently promoted under joint efforts among China,Japan and Korea.EAVN aims at forming a joint VLBI Network by combining a large number of radio telescopes distributed over East Asian regions.After the combination of the Korean VLBI Network(KVN) and the VLBI Exploration of Radio Astrometry(VERA) into Ka VA,further expansion with the joint array in East Asia is actively promoted.Here we report the first imaging results(at 22 and 43 GHz) of bright radio sources obtained with Ka VA connected to Tianma 65-m and Nanshan 26-m Radio Telescopes in China.To test the EAVN imaging performance for different sources,we observed four active galactic nuclei(AGN) having different brightness and morphology.As a result,we confirmed that the Tianma 65-m Radio Telescope(TMRT) significantly enhances the overall array sensitivity,a factor of 4 improvement in baseline sensitivity and 2 in image dynamic range compared to the case of Ka VA only.The addition of the Nanshan 26-m Radio Telescope(NSRT) further doubled the east-west angular resolution.With the resulting high-dynamic-range,high-resolution images with EAVN(Ka VA+TMRT+NSRT),various fine-scale structures in our targets,such as the counter-jet in M87,a kink-like morphology of the 3 C 273 jet and the weak emission in other sources are successfully detected.This demonstrates the powerful capability of EAVN to study AGN jets and to achieve other science goals in general.Ongoing expansion of EAVN will further enhance the angular resolution,detection sensitivity and frequency coverage of the network.展开更多
Based on the three-cathode plasma spraying system,tantalum(Ta)coatings were pre-pared on the substrate of CuCrZr alloy.The effects of different auxiliary gas(helium)flow rates on the microstructure,phase composition,m...Based on the three-cathode plasma spraying system,tantalum(Ta)coatings were pre-pared on the substrate of CuCrZr alloy.The effects of different auxiliary gas(helium)flow rates on the microstructure,phase composition,mechanical and wear resistance properties of Ta coatings were studied.The results showed that the oxidation degree of the coatings decreases first and then increases with the increase of the auxiliary gas flow.When the auxiliary gas flow rate is 70 L·min-1,the oxidation degree of the coating is the lowest,minimum value of the porosity is 0.21%,and the bonding strength reaches the maximum,59.3 MPa.At this time,the coating wear rate is 0.0012 mm^(3)·N^(-1)·m^(-1)with the best wear resistance.This indicates that the auxiliary gas flow has an important influence on the quality and surface mechanical properties of tantalum coating.展开更多
BACKGROUND Left-sided accessory pathways(APs)can be accessed with either a transaortic(TA)or transseptal approach(TS).For children with Marfan syndrome(MFS)who have aortic disease,the use of TA can aggravate the disea...BACKGROUND Left-sided accessory pathways(APs)can be accessed with either a transaortic(TA)or transseptal approach(TS).For children with Marfan syndrome(MFS)who have aortic disease,the use of TA can aggravate the disease,making TS the best choice for these patients.CASE SUMMARY A 10-year-old girl was hospitalized because of intermittent heart palpitations and chest tightness.She was diagnosed with MFS,supraventricular tachycardia,Wolff-Parkinson-White syndrome,and left-sided AP was detected by cardiac electrophysiological.Catheter ablation was successfully performed via TS under the guidance of the Ensite system.During the follow-up,no recurrence or complications occurred.CONCLUSION The TS for catheter ablation of left-sided APs can be considered in children with MFS.Adequate evaluation and selection of the appropriate puncture site are particularly important.展开更多
High resolution imaging of inner jets in Active Galactic Nuclei(AGNs)with Very Long Baseline Interferometry(VLBI)at millimeter wavelengths provides deep insight into the launching and collimation mechanisms of relativ...High resolution imaging of inner jets in Active Galactic Nuclei(AGNs)with Very Long Baseline Interferometry(VLBI)at millimeter wavelengths provides deep insight into the launching and collimation mechanisms of relativistic jets.The BL Lac object,PKS 1749+096,shows a core-dominated jet pointing toward the northeast on parsec-scales revealed by various VLBI observations.In order to investigate the jet kinematics,in particular,the orientation of the inner jet on the smallest accessible scales and the basic physical conditions of the core,in this work we adopted a super-resolution technique,the Bi-Spectrum Maximum Entropy Method(BSMEM),to reanalyze VLBI images based on the Very Long Baseline Array(VLBA)observations of PKS 1749+096 within the VLBA-BU-BLAZAR 7 mm monitoring program.These observations include a total of 105 epochs covering the period from 2009 to 2019.We found that the stacked image of the inner jet is limb-brightened with an apparent opening angle of 50°.0±8°.0 and 42°.0±6°.0 at the distances of 0.2 and 0.3 mas(0.9 and 1.4 pc)from the core,corresponding to an intrinsic jet opening angle of 5°.2±1°.0 and 4°.3±0°.7,respectively.In addition,our images show a clear jet position angle swing in PKS 1749+096 within the last ten years.We discuss the possible implications of jet limb brightening and the connection of the position angle with jet peak flux density and gamma-ray brightness.展开更多
We present quasi-simultaneous VLBI images of the GHz-Peaked-Spectrum radio source OQ 208 obtained with the Very Long Baseline Array at 1.4, 1.7, 2.3, 5.0, 8.4, 15.4 GHz and the European VLBI Network at 6.7 GHz. The lo...We present quasi-simultaneous VLBI images of the GHz-Peaked-Spectrum radio source OQ 208 obtained with the Very Long Baseline Array at 1.4, 1.7, 2.3, 5.0, 8.4, 15.4 GHz and the European VLBI Network at 6.7 GHz. The low frequency （1.4, 1.7 and 2.3 GHz） observations reveal a weak and extended steep-spectrum component at about 30 mas away at position angle - 110°, which may be a remnant emission. The radio structure of OQ 208 consists of two mini-lobes at 5.0, 6.7, 8.4 and 15.4 GHz. Our spectral analysis further confirms that the southwest lobe undergoes free-free absorption and finds that the free-free absorption is stronger in the inner region. By fitting the 8.4 GHz images from 1994 to 2005, we obtain a separation speed of 0.0314-0.006 mas yr^-1 between the two mini-lobes. This indicates a jet proper motion of 0.1054-0.020 c and a kinematic age of 219±42 yr for the radio source.展开更多
Scheduled for launch in 2030,the enhanced X-ray Timing and Polarization(eXTP)telescope is a Chinese space-based mission aimed at studying extreme conditions and phenomena in astrophysics.eXTP will feature three main p...Scheduled for launch in 2030,the enhanced X-ray Timing and Polarization(eXTP)telescope is a Chinese space-based mission aimed at studying extreme conditions and phenomena in astrophysics.eXTP will feature three main payloads:Spectroscopy Focusing Array(SFA),Polarimetry Focusing Array(PFA),and a Wide-field Camera(W2C).This white paper outlines observatory science,incorporating key scientific advances and instrumental changes since the publication of the previous white paper.We will discuss perspectives of eXTP on the research domains of flare stars,supernova remnants,pulsar wind nebulae,cataclysmic variables,X-ray binaries,ultraluminous X-ray sources,active galactic nucleus(AGN),and pulsar-based positioning and timekeeping.展开更多
This study presents a general outline of the Qitai radio telescope(QTT)project.Qitai,the site of the telescope,is a county of Xinjiang Uygur Autonomous Region of China,located in the east Tianshan Mountains at an elev...This study presents a general outline of the Qitai radio telescope(QTT)project.Qitai,the site of the telescope,is a county of Xinjiang Uygur Autonomous Region of China,located in the east Tianshan Mountains at an elevation of about 1800 m.The QTT is a fully steerable,Gregorian-type telescope with a standard parabolic main reflector of 110 m diameter.The QTT has adopted an umbrella support,homology-symmetric lightweight design.The main reflector is active so that the deformation caused by gravity can be corrected.The structural design aims to ultimately allow high-sensitivity observations from 150 MHz up to115 GHz.To satisfy the requirements for early scientific goals,the QTTwill be equipped with ultra-wideband receivers and large field-of-view multi-beam receivers.A multi-function signal-processing system based on RFSo C and GPU processor chips will be developed.These will enable the QTT to operate in pulsar,spectral line,continuum and Very Long Baseline Interferometer(VLBI)observing modes.Electromagnetic compatibility(EMC)and radio frequency interference(RFI)control techniques are adopted throughout the system design.The QTT will form a world-class observational platform for the detection of lowfrequency(nano Hertz)gravitational waves through pulsar timing array(PTA)techniques,pulsar surveys,the discovery of binary black-hole systems,and exploring dark matter and the origin of life in the universe.The QTT will also play an important role in improving the Chinese and international VLBI networks,allowing high-sensitivity and high-resolution observations of the nuclei of distant galaxies and gravitational lensing systems.Deep astrometric observations will also contribute to improving the accuracy of the celestial reference frame.Potentially,the QTT will be able to support future space activities such as planetary exploration in the solar system and to contribute to the search for extraterrestrial intelligence.展开更多
基金funded by the CAS“Light of West China”Program(grant Nos.2021-XBQNXZ-030 and 2021-XBQNXZ-005)the Xinjiang Key Laboratory of Radio Astrophysics(grant No.2023D04064)the National Key R&D Program of China(grant No.2024YFA1611503)。
文摘Accurate estimation of Zenith Tropospheric Delay(ZTD)is essential for mitigating atmospheric effects in radio astronomical observations and improving the retrieval of precipitable water vapor(PWV).In this study,we first analyze the periodic characteristics of ZTD at the NanShan Radio Telescope site using Fourier transform,revealing its dominant seasonal variations,and then investigate the correlation between ZTD and local meteorological parameters,to better understand atmospheric influences on tropospheric delay.Based on these analyses,we propose a hybrid deep learning Gated Recurrent Units-Long Short-Term Memory model,incorporating meteorological parameters as external inputs to enhance ZTD forecasting accuracy.Experimental results demonstrate that the proposed approach achieves a Root Mean Squared Error of 7.97 mm and a correlation coefficient R of 96%,significantly outperforming traditional empirical models and standalone deep learning architectures.These findings indicate that the model effectively captures both short-term dynamics and long-term dependencies in ZTD variations.The improved ZTD predictions not only contribute to reducing atmospheric errors in radio astronomical observations but also provide a more reliable basis for PWV retrieval and forecasting.This study highlights the potential of deep learning in tropospheric delay modeling,offering advancements in both atmospheric science and geodetic applications.
基金supported by the National SKA Program of China(Grant Nos.2020SKA0120104 and 2020SKA0120200)the National Key R&D Program of China(Grant No.2022YFA1603104)the National Natural Science Foundation of China(Grant No.12041301)。
文摘The importance of Very Long Baseline Interferometry(VLBI)for pulsar research is becoming increasingly prominent and receiving more and more attention.We present the pathfinding pulsar observation results with the Chinese VLBI Network(CVN)incorporating the Five-hundred-meter Aperture Spherical radio Telescope(FAST).On MJD 60045(11th April 2023),PSRs B0919+06 and B1133+16 were observed with the phase-referencing mode in the L-band using four radio telescopes(FAST,TianMa,Haoping,and Nanshan)and correlated with the pulsar binning mode of the distributed FX-style software correlator in Shanghai.After further data processing with the NRAO Astronomical Image Processing System(AIPS),we detected these two pulsars and fitted their current positions with accuracy at the milliarcsecond level.By comparison,our results show significantly better agreement with predicted values based on historical VLBI observations than those with previous timing observations,as pulsar astrometry with the VLBI provides a more direct and model-independent method for accurately obtaining related parameters.
基金supported by The Graduate University for Advanced Studies (SOKENDAI)supported by the Japanese Government (MEXT) Scholarship+18 种基金supported by JSPS KAKENHI Grant Numbers JP18K03656 (M.K.),JP18H03721 (K.N.,K.H.and M.K.),JP19H01943 (K.H.,F.T.and Y.H.) and JP18KK0090 (K.H.and F.T.)supported by the Mitsubishi Foundation (grant number 201911019)supported by an EACOA Fellowship awarded by the East Asia Core Observatories Association,which consists of the Academia Sinica Institute of Astronomy and Astrophysics,the National Astronomical Observatory of Japan,the Center for Astronomical Mega-Science,the Chinese Academy of Sciencesthe Korea Astronomy and Space Science Institutethe financial support from the National Research Foundation (NRF) of Korea via Global Ph.D.Fellowship Grant 2014H1A2A1018695 and 2015H1A2A1033752,respectivelysupport from the NRF via Grant 2019R1F1A1059721supported by the Major Program of the National Natural Science Foundation of China (NSFC,Grant Nos.11590780 and 11590784)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No.KJCX1-YW-18)the Scientific Program of Shanghai Municipality (08DZ1160100)Key Laboratory for Radio Astronomy,CASsupport from NSFC (Grant No.11803071)supported by the National Key R&D Program of China (Grant No.2018YFA0404602)the CAS ‘Light of West China’ Program (Grant No.2018-XBQNXZ-B021)the NSFC (Grant Nos.U2031212 and 61931002)the Youth Innovation Promotion Association of the CAS (Grant No.2017084)support from Fundamental Research Grant Scheme (FRGS) FRGS/1/2019/STG02/UM/02/6supported by the Max Planck Partner Group of the MPG and the CASthe support by the Key Program of the NSFC (Grant No.11933007)the Research Program of Fundamental and Frontier Sciences,CAS (Grant No.ZDBS-LY-SLH011)。
文摘The East Asian Very Long Baseline Interferometry(VLBI) Network(EAVN) is a rapidly evolving international VLBI array that is currently promoted under joint efforts among China,Japan and Korea.EAVN aims at forming a joint VLBI Network by combining a large number of radio telescopes distributed over East Asian regions.After the combination of the Korean VLBI Network(KVN) and the VLBI Exploration of Radio Astrometry(VERA) into Ka VA,further expansion with the joint array in East Asia is actively promoted.Here we report the first imaging results(at 22 and 43 GHz) of bright radio sources obtained with Ka VA connected to Tianma 65-m and Nanshan 26-m Radio Telescopes in China.To test the EAVN imaging performance for different sources,we observed four active galactic nuclei(AGN) having different brightness and morphology.As a result,we confirmed that the Tianma 65-m Radio Telescope(TMRT) significantly enhances the overall array sensitivity,a factor of 4 improvement in baseline sensitivity and 2 in image dynamic range compared to the case of Ka VA only.The addition of the Nanshan 26-m Radio Telescope(NSRT) further doubled the east-west angular resolution.With the resulting high-dynamic-range,high-resolution images with EAVN(Ka VA+TMRT+NSRT),various fine-scale structures in our targets,such as the counter-jet in M87,a kink-like morphology of the 3 C 273 jet and the weak emission in other sources are successfully detected.This demonstrates the powerful capability of EAVN to study AGN jets and to achieve other science goals in general.Ongoing expansion of EAVN will further enhance the angular resolution,detection sensitivity and frequency coverage of the network.
基金supported by the National Natural Science Foundation of China(Nos.52076212,U1933107)the Training Fund For Blue Sky Young Scholars of Civil Aviation University of ChinaNatural Science Foundation of Ningbo(No.2019A610173).
文摘Based on the three-cathode plasma spraying system,tantalum(Ta)coatings were pre-pared on the substrate of CuCrZr alloy.The effects of different auxiliary gas(helium)flow rates on the microstructure,phase composition,mechanical and wear resistance properties of Ta coatings were studied.The results showed that the oxidation degree of the coatings decreases first and then increases with the increase of the auxiliary gas flow.When the auxiliary gas flow rate is 70 L·min-1,the oxidation degree of the coating is the lowest,minimum value of the porosity is 0.21%,and the bonding strength reaches the maximum,59.3 MPa.At this time,the coating wear rate is 0.0012 mm^(3)·N^(-1)·m^(-1)with the best wear resistance.This indicates that the auxiliary gas flow has an important influence on the quality and surface mechanical properties of tantalum coating.
文摘BACKGROUND Left-sided accessory pathways(APs)can be accessed with either a transaortic(TA)or transseptal approach(TS).For children with Marfan syndrome(MFS)who have aortic disease,the use of TA can aggravate the disease,making TS the best choice for these patients.CASE SUMMARY A 10-year-old girl was hospitalized because of intermittent heart palpitations and chest tightness.She was diagnosed with MFS,supraventricular tachycardia,Wolff-Parkinson-White syndrome,and left-sided AP was detected by cardiac electrophysiological.Catheter ablation was successfully performed via TS under the guidance of the Ensite system.During the follow-up,no recurrence or complications occurred.CONCLUSION The TS for catheter ablation of left-sided APs can be considered in children with MFS.Adequate evaluation and selection of the appropriate puncture site are particularly important.
基金support from the National Key R&D Program of China(Grant No.2018YFA0404602)the CAS‘Light of West China’Program(Grant No.2018XBQNXZ-B-021)+4 种基金supported by the Max Planck Partner Groups at SHAO and INAOE,respectivelythe support by the Key Program of the National Natural Science Foundation of China(NSFC,Grant No.11933007)the Research Program of Fundamental and Frontier Sciences,CAS(Grant No.ZDBS-LY-SLH011)supported in part by NSFC(Grant Nos.61931002,U1731103)the Youth Innovation Promotion Association of the CAS(No.2017084)。
文摘High resolution imaging of inner jets in Active Galactic Nuclei(AGNs)with Very Long Baseline Interferometry(VLBI)at millimeter wavelengths provides deep insight into the launching and collimation mechanisms of relativistic jets.The BL Lac object,PKS 1749+096,shows a core-dominated jet pointing toward the northeast on parsec-scales revealed by various VLBI observations.In order to investigate the jet kinematics,in particular,the orientation of the inner jet on the smallest accessible scales and the basic physical conditions of the core,in this work we adopted a super-resolution technique,the Bi-Spectrum Maximum Entropy Method(BSMEM),to reanalyze VLBI images based on the Very Long Baseline Array(VLBA)observations of PKS 1749+096 within the VLBA-BU-BLAZAR 7 mm monitoring program.These observations include a total of 105 epochs covering the period from 2009 to 2019.We found that the stacked image of the inner jet is limb-brightened with an apparent opening angle of 50°.0±8°.0 and 42°.0±6°.0 at the distances of 0.2 and 0.3 mas(0.9 and 1.4 pc)from the core,corresponding to an intrinsic jet opening angle of 5°.2±1°.0 and 4°.3±0°.7,respectively.In addition,our images show a clear jet position angle swing in PKS 1749+096 within the last ten years.We discuss the possible implications of jet limb brightening and the connection of the position angle with jet peak flux density and gamma-ray brightness.
基金Supported by the National Natural Science Foundation of China.
文摘We present quasi-simultaneous VLBI images of the GHz-Peaked-Spectrum radio source OQ 208 obtained with the Very Long Baseline Array at 1.4, 1.7, 2.3, 5.0, 8.4, 15.4 GHz and the European VLBI Network at 6.7 GHz. The low frequency （1.4, 1.7 and 2.3 GHz） observations reveal a weak and extended steep-spectrum component at about 30 mas away at position angle - 110°, which may be a remnant emission. The radio structure of OQ 208 consists of two mini-lobes at 5.0, 6.7, 8.4 and 15.4 GHz. Our spectral analysis further confirms that the southwest lobe undergoes free-free absorption and finds that the free-free absorption is stronger in the inner region. By fitting the 8.4 GHz images from 1994 to 2005, we obtain a separation speed of 0.0314-0.006 mas yr^-1 between the two mini-lobes. This indicates a jet proper motion of 0.1054-0.020 c and a kinematic age of 219±42 yr for the radio source.
基金supported by the China’s Space Origins Exploration Program,the National Natural Science Foundation of China(Grant Nos.12273010,12333007,12433004,12233002,12373041,and 12422306)the International Partnership Program of Chinese Academy of Sciences(Grant No.113111KYSB20190020)+9 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA15020100)the Spanish MICIU(Grant Nos.PID2021-124581OB-I0,PID2024-155316NB-I00,and 2021SGR00426)the Ramon y Cajal Fellowship(Grant Nos.RYC2021-032718-I,and RYC2018-025950-I)the European Union NextGenerationEU/PRTR,the Spanish MINECO(Grant Nos.PID2022-136828NB-C44,and PID2023-148661NB-I00)the E.U.FEDER Funds,the AGAUR/Generalitat de Catalunya(Grant No.SGR-386/2021)the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)-Projektnummer(Grant No.549824807)the Programma di Ricerca Fondamentale INAF 2023,the National SKA Program of China(Grant No.2020SKA0120300)the National Key R&D Program of China(Grant No.2021YFA0718500)the Xinjiang Tianchi Program,the Hong Kong Government under HKU(Grant No.17304524)the Bagui Scholars Program.
文摘Scheduled for launch in 2030,the enhanced X-ray Timing and Polarization(eXTP)telescope is a Chinese space-based mission aimed at studying extreme conditions and phenomena in astrophysics.eXTP will feature three main payloads:Spectroscopy Focusing Array(SFA),Polarimetry Focusing Array(PFA),and a Wide-field Camera(W2C).This white paper outlines observatory science,incorporating key scientific advances and instrumental changes since the publication of the previous white paper.We will discuss perspectives of eXTP on the research domains of flare stars,supernova remnants,pulsar wind nebulae,cataclysmic variables,X-ray binaries,ultraluminous X-ray sources,active galactic nucleus(AGN),and pulsar-based positioning and timekeeping.
基金supported by the National Key Research and Development Program of China(Grant Nos.2021YFC2203501,2021YFC2203502,2021YFC2203503,and 2021YFC2203600)the National Natural Science Foundation of China(Grant Nos.12173077,11873082,11803080,and 12003062)+3 种基金the Scientific Instrument Developing Project of the Chinese Academy of Sciences(Grant No.PTYQ2022YZZD01)the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instrumentsbudgeted from the Ministry of Finance of China and Administrated by the Chinese Academy of Sciencesthe Chinese Academy of Sciences“Light of West China”Program(Grant No.2021-XBQNXZ-030)。
文摘This study presents a general outline of the Qitai radio telescope(QTT)project.Qitai,the site of the telescope,is a county of Xinjiang Uygur Autonomous Region of China,located in the east Tianshan Mountains at an elevation of about 1800 m.The QTT is a fully steerable,Gregorian-type telescope with a standard parabolic main reflector of 110 m diameter.The QTT has adopted an umbrella support,homology-symmetric lightweight design.The main reflector is active so that the deformation caused by gravity can be corrected.The structural design aims to ultimately allow high-sensitivity observations from 150 MHz up to115 GHz.To satisfy the requirements for early scientific goals,the QTTwill be equipped with ultra-wideband receivers and large field-of-view multi-beam receivers.A multi-function signal-processing system based on RFSo C and GPU processor chips will be developed.These will enable the QTT to operate in pulsar,spectral line,continuum and Very Long Baseline Interferometer(VLBI)observing modes.Electromagnetic compatibility(EMC)and radio frequency interference(RFI)control techniques are adopted throughout the system design.The QTT will form a world-class observational platform for the detection of lowfrequency(nano Hertz)gravitational waves through pulsar timing array(PTA)techniques,pulsar surveys,the discovery of binary black-hole systems,and exploring dark matter and the origin of life in the universe.The QTT will also play an important role in improving the Chinese and international VLBI networks,allowing high-sensitivity and high-resolution observations of the nuclei of distant galaxies and gravitational lensing systems.Deep astrometric observations will also contribute to improving the accuracy of the celestial reference frame.Potentially,the QTT will be able to support future space activities such as planetary exploration in the solar system and to contribute to the search for extraterrestrial intelligence.
