Purpose The Einstein Probe(EP)satellite is a science mission of the Chinese Academy of Sciences,which is dedicated to time-domain astronomy and high-energy astrophysics.The X-ray baffle is a crucial component of follo...Purpose The Einstein Probe(EP)satellite is a science mission of the Chinese Academy of Sciences,which is dedicated to time-domain astronomy and high-energy astrophysics.The X-ray baffle is a crucial component of follow-up X-ray telescope(FXT),which is an important payload onboard EP.It was designed to efficiently reduce stray light,especially single reflection on the hyperboloid of Wolter-I Mirrors.Methods In this paper,based on the parameters of FXT's mirror module and the detector,the design parameters of the X-ray baffle are optimized through preliminary design and detailed ray-tracing simulation.Fabrication involved precision laser cutting,roll forming,laser welding and integration processes.The thermal stability and mechanical environment adaptability were validated through thermal cycling and mechanical vibration tests.Finally,the X-ray baffle was mounted onto the mirror module with alignment precisely controlled using optical methods.Results The height of the X-ray baffle ranges from 60 to 120 mm from the outside to the inside;the aperture corresponds to each layer of the mirror module.In order to reduce weight and reduce light occlusion,the thickness of each thin shell is 0.125 mm.The ray-tracing simulation results with X-ray baffle are shown that the stray light is effectively reduced in the effective region of the detector.The Eigen-frequency change of the X-ray baffle after the thermal cycle test and mechanical vibration tests is only 0.52%and 0.77%,respectively.The results proved that X-ray baffle has a high thermo-mechanical reliability.The half power diameter(HPD)of the mirror module remained unchanged on-axis with/without X-ray baffle.Conclusion The introduction of X-ray baffle is expected to be highly significantly reduce stray light.展开更多
Purpose The follow-up X-ray telescope(FXT)is one of the two payloads of the Einstein Probe(EP),consisting of the upper composite with the X-ray mirror module as the core,the lower composite with the pnCCD module as th...Purpose The follow-up X-ray telescope(FXT)is one of the two payloads of the Einstein Probe(EP),consisting of the upper composite with the X-ray mirror module as the core,the lower composite with the pnCCD module as the core,and the interface structure.The FXT thermal control subsystem is responsible for the thermal design,thermal implementations,and testing of the entire FXT payload thermal control.Methods A design approach is adopted with passive thermal control technology as the main method and active thermal control technology as a supplement for common components.The X-ray mirror modules are high-precision optical components,utilizing active closed-loop temperature control to ensure high precision and stability.The pnCCD detectors operate at a stable low temperature,with refrigerators used to cool the detector houses,ensuring they can operate under stable low-temperature conditions.The hot ends of the refrigerators are connected to the external radiator panels through heat pipes for heat dissipation.Results The thermal control subsystem of FXT is operating properly in-orbit.All component temperatures meet the design requirements.Conclusion After multiple rounds of design and test verification,FXT was successfully launched with EP and completed in-orbit testing.During the in-orbit testing phase of EP,the function of the FXT thermal control subsystem works well.The temperatures of the components and units are normal.This paper introduces the design of FXT thermal control and the in-orbit performance of the thermal control subsystem.展开更多
Purpose The Einstein Probe(EP)satellite is a space X-ray satellite for time-domain astronomy and high-energy astrophysics.The precision control of the optical structure directly affects the imaging quality and positio...Purpose The Einstein Probe(EP)satellite is a space X-ray satellite for time-domain astronomy and high-energy astrophysics.The precision control of the optical structure directly affects the imaging quality and positioning accuracy of the Follow-up X-ray Telescope(FXT),playing a crucial role in achieving the on-orbit scientific objectives of the FXT.Higher positioning accuracy makes it easier to identify corresponding bodies for the discovery and positioning of transient sources.Accurate positioning is beneficial for follow-up observations in other bands,such as optical spectroscopy.Methods This article mainly introduces the precision control methods and processes of the FXT optical structure,which have been tested and verified through satellite test.The on-orbit source positioning accuracy of the FXT telescope is within 20 arcseconds(90% confidence level),meeting the requirements of the FXT mission.Results and Conclusion To ensure the accuracy of the EP satellite’s FXT optical structure,measures such as component processing control,installation control,and posttest adjustments are taken on the ground to ensure that the detector mounting position,optical axis deviation,and other precision indicators before and after the satellite lever test meet the design requirements.After a successful launch,through on-orbit calibration,the FXT-A and FXT-B optical axis pointing direction deviation is 39 arcseconds,and the source positioning error is better than 3'' at 68% confidence level.FXT optical structure meets all the requirements from design,processing,installation,etc.,successfully meeting scientific needs.展开更多
Purpose The Einstein Probe(EP)is an X-ray astronomical satellite designed for time-domain astronomy.The Follow-up X-ray Telescope(FXT)is an important payload on the EP.The FXT’s detector utilizes a pn-junction charge...Purpose The Einstein Probe(EP)is an X-ray astronomical satellite designed for time-domain astronomy.The Follow-up X-ray Telescope(FXT)is an important payload on the EP.The FXT’s detector utilizes a pn-junction charge-coupled device(pnCCD),which is currently the fastest-readout X-ray CCD worldwide.The design and implementation of a dedicated power-supply and monitoring module constitute a key aspect in the development of the detector system.Methods The FXT comprises several components,including the electric control box(EC-Box),the detector electronics box(DE-Box),and the focusing camera.The detector module of the focusing camera consists of two primary components:the pnCCD and the multi-channel analog signal processing chip known as the CAMEX(CMOS amplifier and multiplexer)ASIC.The CAMEX ASIC is used for the readout of the pnCCD signals.The operation of the detector module requires a sophisticated power-supply module.This paper details the design and implementation of a dedicated power-supply and monitoring module for the detector module.Based on the voltage requirements of the detector module,the power-supply module has been designed to include switchable,adjustable,and programmable functions.The monitoring module includes voltage,current,and temperature monitoring based on the different types of monitoring.Results The power-supply and monitoring module operates reliably and performs effectively in orbit,meeting the requirements of the FXT payload on the EP satellite.Conclusion The power-supply and monitoring module has successfully provided a stable power-supply and monitoring module for the detector module.It operates effectively in orbit,ensuring that the detector system achieves optimal performance.展开更多
Background The Einstein probe(EP)is an X-ray astronomical satellite dedicated to time-domain astronomy and high-energy astrophysics.Initiated at the end of 2017,it was successfully launched on January 9,2024.The follo...Background The Einstein probe(EP)is an X-ray astronomical satellite dedicated to time-domain astronomy and high-energy astrophysics.Initiated at the end of 2017,it was successfully launched on January 9,2024.The follow-up X-ray telescope(FXT)is a key payload on the EP satellite.The FXT employs PNCCD as its focal plane detector.Its electronic components include the electronic control box(EC-Box),the detector electronics boxes(DE-Box),the refrigerator controller,the movement mechanisms controller,and the temperature control instrument.Methods The FXT conducted functional performance tests in-orbit as planned,including three operating modes of the detector,energy detection range,and energy resolution.Results Since FXT became operational in orbit,all electronic equipment has been working stably.The FXT has an energy detection range of 0.3-10 keV,with an energy resolution of approximately 92 eV@1.25 keV,and an electronic noise of about 3.3e^(-).展开更多
Purpose The Einstein Probe(EP)is a space X-ray mission dedicated to the time-domain astrophysics,aiming to discover high-energy transients and monitor variable objects.As a principal scientific payload onboard EP,the ...Purpose The Einstein Probe(EP)is a space X-ray mission dedicated to the time-domain astrophysics,aiming to discover high-energy transients and monitor variable objects.As a principal scientific payload onboard EP,the Follow-up X-ray Telescope(FXT)mainly responses for prompt and deep follow-up observations of the triggered targets by EP-WXT and discovers and characterizes X-ray transients,particularly faint or distant X-ray transients.Since these transient signals fade rapidly or evolve dramatically,a fast and reliable analysis of the FXT data is essential to discover them and trigger timely and efficient follow-up observations,which is important to identify the nature of these sources.Methods To address this issue,we develop a real-time source search toolkit to automatically process EP-FXT observations in real time,detecting all the sources in the field of view of FXT,extracting their scientific information,and searching for transients and bursts.Accordingly,the toolkit consists of three modules:source detection,source information extraction,and source identification.Results The toolkit outcomes a quick-look database:1)a series of high-level scientific products for every observed source,such as the position,count rate,flux,variability amplitude,hardness,light curve,an absorbed powerlaw or blackbody model fitted spectrum,and the power density spectrum;2)transients and bursts;3)source list;4)sky map.As the software is automatically running,this quick-look database is continuously updated.Conclusion The real-time source search toolkit can process all the observed data and effectively meets the fast source search requirements of FXT.展开更多
Purpose:In order to evaluate the mechanical feasibility of the domestic baffle made by wire electrode cutting for the mirror assembly of the Follow-up X-ray Telescope(FXT)onboard the Einstein Probe(EP)mission.Methods:...Purpose:In order to evaluate the mechanical feasibility of the domestic baffle made by wire electrode cutting for the mirror assembly of the Follow-up X-ray Telescope(FXT)onboard the Einstein Probe(EP)mission.Methods:Finite element analysis was performed to compare the structural differences between the domestic baffle made by wire electrode cutting and the eROSITA baffle made by bonding.The finite element models were verified by test data in advance to avoid significant deviations.Finally,the differences in dynamical performances between the FXT mirror assemblies with the two baffles were investigated through modal analysis and frequency response analysis using the pre-verified models.Results and conclusions:The results show that,from the perspective of the entire mirror assembly,their eigenfrequencies remain similar,except for the second lateral eigenfrequency,which shifts forward by approximately 24 Hz in the mirror assembly equipped with the domestic baffle.However,for the X-ray baffles themselves,the axial and lateral eigenfrequencies of the two baffles differ by approximately 49 Hz and 185 Hz,respectively.These eigenfrequencies are staggered,ensuring that over-response is avoided.In terms of response amplification,the domestic baffle,compared to the eROSITA baffle,exhibits inferior axial mechanical characteristics but superior lateral characteristics.In summary,from a mechanical perspective,the domestic baffle is feasible.展开更多
Background:The Einstein Probe(EP)is a space X-ray astronomical mission of China-Europe collaboration,launched on January 9,2024,and is equipped with two types of scientific payloads,the wide-field X-ray telescope(WXT)...Background:The Einstein Probe(EP)is a space X-ray astronomical mission of China-Europe collaboration,launched on January 9,2024,and is equipped with two types of scientific payloads,the wide-field X-ray telescope(WXT)and the follow-up X-ray telescope(FXT).Methods:The FXT payload was developed by the Institute of High Energy Physics(IHEP).Consequently,the EP-FXT Science Data Center(SDC)was established at IHEP to manage the processing of FXT data.Results and conclusion:The EP-FXT SDC has maintained a continuous and stable operation since the EP’s launch.It has provided the standard data products,released the data analysis software and calibration database,and supported the science users in conducting scientific research.In this paper,we present a systematic and comprehensive overview of the primary workflows and key tasks of the FXT science data center.展开更多
The Einstein Probe(EP)satellite represents a significant milestone in China's pursuit of advancing time-domain astronomy and high-energy astrophysics.At its core lies the Follow-up X-ray Telescope(FXT),a groundbre...The Einstein Probe(EP)satellite represents a significant milestone in China's pursuit of advancing time-domain astronomy and high-energy astrophysics.At its core lies the Follow-up X-ray Telescope(FXT),a groundbreaking payload that marks China's first foray into Wolter-I focusing technology for X-ray imaging.Designed with a dual-telescope structure,FXT incorporates 54 layers of ultra-smooth,gold-coated nickel mirror shells nested within each focusing mirror,paired with an advanced PNCCD focal plane detector,coupled with an advanced PNCCD focal plane detector.展开更多
Background:The Einstein Probe mission is an astronomical satellite developed in China,focusing on time-domain astronomy in the soft X-ray energy band.A key payload of this mission is the follow-up X-ray telescope(FXT)...Background:The Einstein Probe mission is an astronomical satellite developed in China,focusing on time-domain astronomy in the soft X-ray energy band.A key payload of this mission is the follow-up X-ray telescope(FXT),which is the result of international collaboration between China and Europe.The FXT features gold-coated nickel Wolter-I-type focusing mirrors and utilizes PNCCD detectors for imaging and spectroscopy in the focal plane.Methods:We reviewed the seven-year development history of the FXT.Initially,the configuration of the FXT consisted of a single telescope unit in 2017,but it later evolved into a dual-unit setup.Building on the successful design of eROSITA,the FXT team has innovatively introduced new operational modes for the PNCCD.FXT team also developed an ultra-compact helium pulse tube refrigerator,which cools the PNCCD down to-90℃.Additionally,various passive shielding measures have been implemented to protect against high-energy charged particles and enhance radiation resistance.These advancements have significantly improved the overall performance and reliability of the FXT.Results and conclusion:The ground calibrations and tests of the FXT demonstrate that its primary performance meets the established design goals.The FXT has exhibited outstanding performance in orbit,establishing itself as one of the space X-ray telescopes with considerable international influence.展开更多
The Einstein Probe(EP)mission,approved by the Chinese Academy of Sciences(CAS)in 2017 and launched in 2024,is a significant advancement in time-domain astronomy.The Follow-up X-ray Telescope(FXT),equipped with a Wolte...The Einstein Probe(EP)mission,approved by the Chinese Academy of Sciences(CAS)in 2017 and launched in 2024,is a significant advancement in time-domain astronomy.The Follow-up X-ray Telescope(FXT),equipped with a Wolter I focusing mirror system and a PNCCD detector,is critical for detecting and analyzing cosmic X-rays.To ensure its reliability in space,structural and structural-thermal models were developed,and mechanical and thermal tests were conducted to verify its ability to withstand launch stresses and space conditions.The Wolter I mirrors,manufactured and integrated by the HIT team,achieved an angular resolution of 57 arcseconds at 1.5 keV and an effective area of 250 cm^(2).This paper presents the verification results of these tests,including insights from the flight spare model,and discusses potential reasons for the observed loss of effective area,such as alignment imperfections or thermal distortions.These findings are essential for optimizing the FXT’s design and ensuring the mission’s success,highlighting the importance of rigorous testing in space-based observatory development.展开更多
Purpose In this work,we present the pile-up fractions on the follow-up X-ray telescope(FXT)onboard Einstein Probe using its different read-out modes and filters for various source fluxes.This investigation could help ...Purpose In this work,we present the pile-up fractions on the follow-up X-ray telescope(FXT)onboard Einstein Probe using its different read-out modes and filters for various source fluxes.This investigation could help understand the pile-up effect on FXT and choose the filter and readout mode when observing dedicated sources.Methods We use the Simulation of X-ray Telescopes package to conduct the simulation from incidence of photons from celestial sources to the detection on the FXT pnCCD.Based on the reconstructed signals,we make a statistic on the counts of incident photons and detected events to obtain the pile-up fraction for each set of read-out mode and filter configuration.Results and conclusion From the perspective of incident photons among all detected events,the pile-up fraction increases monotonically with the brightness of the source.From the viewpoints of valid detected events,the fraction values exhibit an initial nonlinear increase,followed by a decrease,and a subsequent increase as the source fluxes increase,attributed to the presence of pile-up effects and the selection criteria for valid events.For some certain fluxes,the fraction value is larger in faster readout modes than lower modes.From the viewpoint of incident photon in valid detected events,a 10% pile-up fraction corresponds to 5 mCrab in full frame mode(FF),120 mCrab in partial windowed mode(PW),3 Crab in Timing mode(TM)under the medium filter type.At these fluxes,the deviation of the fitted photon indices is within 10% from that of the input source model.展开更多
基金supported by the Natural Science Basic Research Program of Shaanxi Province(2024JC-YBMS-532)the Natural Science Basic Research Program of Shaanxi Province(2023-JC-ZD-40)+1 种基金the Natural Science Basic Research Program of Shaanxi Province(2024JC-YBQN-0003)the Natural Science Basic Research Program of Shaanxi Province(2024JC-YBQN-0686).
文摘Purpose The Einstein Probe(EP)satellite is a science mission of the Chinese Academy of Sciences,which is dedicated to time-domain astronomy and high-energy astrophysics.The X-ray baffle is a crucial component of follow-up X-ray telescope(FXT),which is an important payload onboard EP.It was designed to efficiently reduce stray light,especially single reflection on the hyperboloid of Wolter-I Mirrors.Methods In this paper,based on the parameters of FXT's mirror module and the detector,the design parameters of the X-ray baffle are optimized through preliminary design and detailed ray-tracing simulation.Fabrication involved precision laser cutting,roll forming,laser welding and integration processes.The thermal stability and mechanical environment adaptability were validated through thermal cycling and mechanical vibration tests.Finally,the X-ray baffle was mounted onto the mirror module with alignment precisely controlled using optical methods.Results The height of the X-ray baffle ranges from 60 to 120 mm from the outside to the inside;the aperture corresponds to each layer of the mirror module.In order to reduce weight and reduce light occlusion,the thickness of each thin shell is 0.125 mm.The ray-tracing simulation results with X-ray baffle are shown that the stray light is effectively reduced in the effective region of the detector.The Eigen-frequency change of the X-ray baffle after the thermal cycle test and mechanical vibration tests is only 0.52%and 0.77%,respectively.The results proved that X-ray baffle has a high thermo-mechanical reliability.The half power diameter(HPD)of the mirror module remained unchanged on-axis with/without X-ray baffle.Conclusion The introduction of X-ray baffle is expected to be highly significantly reduce stray light.
基金supported by the Einstein-Probe(EP)Program which is funded by the Strategic Priority Research Program of the Chinese Academy of Sciences Grant No.XDA15310103.
文摘Purpose The follow-up X-ray telescope(FXT)is one of the two payloads of the Einstein Probe(EP),consisting of the upper composite with the X-ray mirror module as the core,the lower composite with the pnCCD module as the core,and the interface structure.The FXT thermal control subsystem is responsible for the thermal design,thermal implementations,and testing of the entire FXT payload thermal control.Methods A design approach is adopted with passive thermal control technology as the main method and active thermal control technology as a supplement for common components.The X-ray mirror modules are high-precision optical components,utilizing active closed-loop temperature control to ensure high precision and stability.The pnCCD detectors operate at a stable low temperature,with refrigerators used to cool the detector houses,ensuring they can operate under stable low-temperature conditions.The hot ends of the refrigerators are connected to the external radiator panels through heat pipes for heat dissipation.Results The thermal control subsystem of FXT is operating properly in-orbit.All component temperatures meet the design requirements.Conclusion After multiple rounds of design and test verification,FXT was successfully launched with EP and completed in-orbit testing.During the in-orbit testing phase of EP,the function of the FXT thermal control subsystem works well.The temperatures of the components and units are normal.This paper introduces the design of FXT thermal control and the in-orbit performance of the thermal control subsystem.
基金supported by the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences(Grant No.XDA 15310103).
文摘Purpose The Einstein Probe(EP)satellite is a space X-ray satellite for time-domain astronomy and high-energy astrophysics.The precision control of the optical structure directly affects the imaging quality and positioning accuracy of the Follow-up X-ray Telescope(FXT),playing a crucial role in achieving the on-orbit scientific objectives of the FXT.Higher positioning accuracy makes it easier to identify corresponding bodies for the discovery and positioning of transient sources.Accurate positioning is beneficial for follow-up observations in other bands,such as optical spectroscopy.Methods This article mainly introduces the precision control methods and processes of the FXT optical structure,which have been tested and verified through satellite test.The on-orbit source positioning accuracy of the FXT telescope is within 20 arcseconds(90% confidence level),meeting the requirements of the FXT mission.Results and Conclusion To ensure the accuracy of the EP satellite’s FXT optical structure,measures such as component processing control,installation control,and posttest adjustments are taken on the ground to ensure that the detector mounting position,optical axis deviation,and other precision indicators before and after the satellite lever test meet the design requirements.After a successful launch,through on-orbit calibration,the FXT-A and FXT-B optical axis pointing direction deviation is 39 arcseconds,and the source positioning error is better than 3'' at 68% confidence level.FXT optical structure meets all the requirements from design,processing,installation,etc.,successfully meeting scientific needs.
基金supported by the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences(Grant No.XDA 15310103).
文摘Purpose The Einstein Probe(EP)is an X-ray astronomical satellite designed for time-domain astronomy.The Follow-up X-ray Telescope(FXT)is an important payload on the EP.The FXT’s detector utilizes a pn-junction charge-coupled device(pnCCD),which is currently the fastest-readout X-ray CCD worldwide.The design and implementation of a dedicated power-supply and monitoring module constitute a key aspect in the development of the detector system.Methods The FXT comprises several components,including the electric control box(EC-Box),the detector electronics box(DE-Box),and the focusing camera.The detector module of the focusing camera consists of two primary components:the pnCCD and the multi-channel analog signal processing chip known as the CAMEX(CMOS amplifier and multiplexer)ASIC.The CAMEX ASIC is used for the readout of the pnCCD signals.The operation of the detector module requires a sophisticated power-supply module.This paper details the design and implementation of a dedicated power-supply and monitoring module for the detector module.Based on the voltage requirements of the detector module,the power-supply module has been designed to include switchable,adjustable,and programmable functions.The monitoring module includes voltage,current,and temperature monitoring based on the different types of monitoring.Results The power-supply and monitoring module operates reliably and performs effectively in orbit,meeting the requirements of the FXT payload on the EP satellite.Conclusion The power-supply and monitoring module has successfully provided a stable power-supply and monitoring module for the detector module.It operates effectively in orbit,ensuring that the detector system achieves optimal performance.
基金supported by the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences Grant No.XDA15310103.
文摘Background The Einstein probe(EP)is an X-ray astronomical satellite dedicated to time-domain astronomy and high-energy astrophysics.Initiated at the end of 2017,it was successfully launched on January 9,2024.The follow-up X-ray telescope(FXT)is a key payload on the EP satellite.The FXT employs PNCCD as its focal plane detector.Its electronic components include the electronic control box(EC-Box),the detector electronics boxes(DE-Box),the refrigerator controller,the movement mechanisms controller,and the temperature control instrument.Methods The FXT conducted functional performance tests in-orbit as planned,including three operating modes of the detector,energy detection range,and energy resolution.Results Since FXT became operational in orbit,all electronic equipment has been working stably.The FXT has an energy detection range of 0.3-10 keV,with an energy resolution of approximately 92 eV@1.25 keV,and an electronic noise of about 3.3e^(-).
基金supported by the Einstein Probe(EP)Program which is funded by the Strategic Priority Research Program of the Chinese Academy of Sciences Grant No.XDA15310303the National Natural Science Foundation of China under Grant No.U2038102,U1938102.
文摘Purpose The Einstein Probe(EP)is a space X-ray mission dedicated to the time-domain astrophysics,aiming to discover high-energy transients and monitor variable objects.As a principal scientific payload onboard EP,the Follow-up X-ray Telescope(FXT)mainly responses for prompt and deep follow-up observations of the triggered targets by EP-WXT and discovers and characterizes X-ray transients,particularly faint or distant X-ray transients.Since these transient signals fade rapidly or evolve dramatically,a fast and reliable analysis of the FXT data is essential to discover them and trigger timely and efficient follow-up observations,which is important to identify the nature of these sources.Methods To address this issue,we develop a real-time source search toolkit to automatically process EP-FXT observations in real time,detecting all the sources in the field of view of FXT,extracting their scientific information,and searching for transients and bursts.Accordingly,the toolkit consists of three modules:source detection,source information extraction,and source identification.Results The toolkit outcomes a quick-look database:1)a series of high-level scientific products for every observed source,such as the position,count rate,flux,variability amplitude,hardness,light curve,an absorbed powerlaw or blackbody model fitted spectrum,and the power density spectrum;2)transients and bursts;3)source list;4)sky map.As the software is automatically running,this quick-look database is continuously updated.Conclusion The real-time source search toolkit can process all the observed data and effectively meets the fast source search requirements of FXT.
基金supported by the Einstein Probe(EP)Program which is funded by the"Strategic Priority Research Program"of the Chinese Academy of Sciences(Grant No.XDA15310103).
文摘Purpose:In order to evaluate the mechanical feasibility of the domestic baffle made by wire electrode cutting for the mirror assembly of the Follow-up X-ray Telescope(FXT)onboard the Einstein Probe(EP)mission.Methods:Finite element analysis was performed to compare the structural differences between the domestic baffle made by wire electrode cutting and the eROSITA baffle made by bonding.The finite element models were verified by test data in advance to avoid significant deviations.Finally,the differences in dynamical performances between the FXT mirror assemblies with the two baffles were investigated through modal analysis and frequency response analysis using the pre-verified models.Results and conclusions:The results show that,from the perspective of the entire mirror assembly,their eigenfrequencies remain similar,except for the second lateral eigenfrequency,which shifts forward by approximately 24 Hz in the mirror assembly equipped with the domestic baffle.However,for the X-ray baffles themselves,the axial and lateral eigenfrequencies of the two baffles differ by approximately 49 Hz and 185 Hz,respectively.These eigenfrequencies are staggered,ensuring that over-response is avoided.In terms of response amplification,the domestic baffle,compared to the eROSITA baffle,exhibits inferior axial mechanical characteristics but superior lateral characteristics.In summary,from a mechanical perspective,the domestic baffle is feasible.
基金supported by the Einstein-Probe(EP)Program which is funded by the Strategic Priority Research Program of the Chinese Academy of Sciences Grant No.XDA15310303.
文摘Background:The Einstein Probe(EP)is a space X-ray astronomical mission of China-Europe collaboration,launched on January 9,2024,and is equipped with two types of scientific payloads,the wide-field X-ray telescope(WXT)and the follow-up X-ray telescope(FXT).Methods:The FXT payload was developed by the Institute of High Energy Physics(IHEP).Consequently,the EP-FXT Science Data Center(SDC)was established at IHEP to manage the processing of FXT data.Results and conclusion:The EP-FXT SDC has maintained a continuous and stable operation since the EP’s launch.It has provided the standard data products,released the data analysis software and calibration database,and supported the science users in conducting scientific research.In this paper,we present a systematic and comprehensive overview of the primary workflows and key tasks of the FXT science data center.
文摘The Einstein Probe(EP)satellite represents a significant milestone in China's pursuit of advancing time-domain astronomy and high-energy astrophysics.At its core lies the Follow-up X-ray Telescope(FXT),a groundbreaking payload that marks China's first foray into Wolter-I focusing technology for X-ray imaging.Designed with a dual-telescope structure,FXT incorporates 54 layers of ultra-smooth,gold-coated nickel mirror shells nested within each focusing mirror,paired with an advanced PNCCD focal plane detector,coupled with an advanced PNCCD focal plane detector.
基金supported by the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences(Grant No.XDA 15310103).
文摘Background:The Einstein Probe mission is an astronomical satellite developed in China,focusing on time-domain astronomy in the soft X-ray energy band.A key payload of this mission is the follow-up X-ray telescope(FXT),which is the result of international collaboration between China and Europe.The FXT features gold-coated nickel Wolter-I-type focusing mirrors and utilizes PNCCD detectors for imaging and spectroscopy in the focal plane.Methods:We reviewed the seven-year development history of the FXT.Initially,the configuration of the FXT consisted of a single telescope unit in 2017,but it later evolved into a dual-unit setup.Building on the successful design of eROSITA,the FXT team has innovatively introduced new operational modes for the PNCCD.FXT team also developed an ultra-compact helium pulse tube refrigerator,which cools the PNCCD down to-90℃.Additionally,various passive shielding measures have been implemented to protect against high-energy charged particles and enhance radiation resistance.These advancements have significantly improved the overall performance and reliability of the FXT.Results and conclusion:The ground calibrations and tests of the FXT demonstrate that its primary performance meets the established design goals.The FXT has exhibited outstanding performance in orbit,establishing itself as one of the space X-ray telescopes with considerable international influence.
基金supported by the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences,Grant No.XDA1531010301.
文摘The Einstein Probe(EP)mission,approved by the Chinese Academy of Sciences(CAS)in 2017 and launched in 2024,is a significant advancement in time-domain astronomy.The Follow-up X-ray Telescope(FXT),equipped with a Wolter I focusing mirror system and a PNCCD detector,is critical for detecting and analyzing cosmic X-rays.To ensure its reliability in space,structural and structural-thermal models were developed,and mechanical and thermal tests were conducted to verify its ability to withstand launch stresses and space conditions.The Wolter I mirrors,manufactured and integrated by the HIT team,achieved an angular resolution of 57 arcseconds at 1.5 keV and an effective area of 250 cm^(2).This paper presents the verification results of these tests,including insights from the flight spare model,and discusses potential reasons for the observed loss of effective area,such as alignment imperfections or thermal distortions.These findings are essential for optimizing the FXT’s design and ensuring the mission’s success,highlighting the importance of rigorous testing in space-based observatory development.
基金supported by the Einstein-Probe(EP)Program which is funded by the Strategic Priority Research Program of the Chinese Academy of Sciences Grant No.XDA15310303 and No.XDA15310000.
文摘Purpose In this work,we present the pile-up fractions on the follow-up X-ray telescope(FXT)onboard Einstein Probe using its different read-out modes and filters for various source fluxes.This investigation could help understand the pile-up effect on FXT and choose the filter and readout mode when observing dedicated sources.Methods We use the Simulation of X-ray Telescopes package to conduct the simulation from incidence of photons from celestial sources to the detection on the FXT pnCCD.Based on the reconstructed signals,we make a statistic on the counts of incident photons and detected events to obtain the pile-up fraction for each set of read-out mode and filter configuration.Results and conclusion From the perspective of incident photons among all detected events,the pile-up fraction increases monotonically with the brightness of the source.From the viewpoints of valid detected events,the fraction values exhibit an initial nonlinear increase,followed by a decrease,and a subsequent increase as the source fluxes increase,attributed to the presence of pile-up effects and the selection criteria for valid events.For some certain fluxes,the fraction value is larger in faster readout modes than lower modes.From the viewpoint of incident photon in valid detected events,a 10% pile-up fraction corresponds to 5 mCrab in full frame mode(FF),120 mCrab in partial windowed mode(PW),3 Crab in Timing mode(TM)under the medium filter type.At these fluxes,the deviation of the fitted photon indices is within 10% from that of the input source model.
