Explore the vast range of titles available.

The Einstein Probe (EP) satellite is designed for X-ray time-domain astronomy. The Follow-up X-ray Telescope (FXT) is one of the scientific payloads onboard EP. It will mainly be used for the follow-up X-ray observation, and it will also be used for the sky survey and Target of Opportunity (ToO) observation. The focal plane detector of FXT provided by the Max Planck Institute for Extraterrestrial Physics (MPE) adopts a PNCCD sensor. For detector cooling, a helium pulse tube refrigerator is used, provided by the Technical Institute of Physics and Chemistry (TIPC), Chinese Academy of Sciences (CAS), to keep the detector working at a temperature of −90 ± 0.5 °C. The PNCCD driving and data acquisition electronics are developed by the Institute of High Energy Physics (IHEP), CAS. To observe different celestial sources, we designed six filter wheel positions and three scientific operating modes for the PNCCD detector: the full-frame mode, the partial-window mode, and the timing mode. In the full-frame mode, the system frame rate is 20 frame/s and the energy resolution of the whole system reaches 92 eV @ 1.49 keV (FWHM). The frame rate of partial-window mode is 500 frame/s. In the timing mode, the time resolution is about 94 μs. This paper mainly introduces the design and test results of the focal plane camera.

The Einstein Probe (EP) mission is a science mission designed for the time domain astronomy, which is approved by the Chinese Academy of Sciences (CAS) in 2017 and is to be launched in 2023 with a duration time of more than 3 years. The Follow-up X-ray Telescope (FXT) is an important payload onboard EP, which employs the Wolter I focusing mirror as the X-ray collection unit and the PNCCD as the focal plane detector. The Phase C study has been finished in 2021. During the Phase C, the structural and thermal model (STM) of the mirror assembly of FXT, provided by the European Space Agency (ESA), a mirror assembly developed by the Institute of High Energy Physics (IHEP), a qualification model (QM) PNCCD and other components, are integrated and tested in IHEP. All optical performances meet the goal requirement of EP, such as the field of view of 60 arcmins, the angular resolution of less than 30 arcsec HEW on-axis, and the focal length of ab. 1600 mm. After that, the FXT is assembled, integrated, and tested on the EP satellite platform. Furthermore, these performances are not changed after the mechanical and thermal tests on the spacecraft platform.

The Follow-up X-ray Telescope (FXT) is one of the key payloads onboard EP. It is a Wolter-I type X-ray focusing telescope equipped with two telescope modules (focal length 1.6 m), with a total effective area of ~ 600 cm2 at 1.25 keV and an energy range of 0.3–10 keV. FXT is mainly composed of an X-ray focusing mirror assembly (MA) and a camera assembly with a PNCCD detector module. The two FXT modules are completely independent from each other, thus avoiding a single point failure. We completed the internal composites of FXT structural design, which meets the function and performance requirements of mechanical, thermal, contamination control and X-ray optics. The FXT passed successfully the mechanical, thermal qualification level tests on the spacecraft platform in the phase C.

PurposeDesign and implement a system within the detector electronic box of the FXT payload on the EP satellite to read out and acquire data from the pnCCD module of the focal plane detector.MethodsThe pnCCD module is complex to control, has a high data throughput, and poses challenges during readout. This paper presents the design and implementation of a data acquisition system specifically for pnCCD and its readout ASIC, CAMEX. The DAQ includes a dedicated front-end module for signal conversion, a control module for powering the pnCCD on and off and managing its sequence, and a signal preprocessing module that performs real-time corrections for offset and common mode on signals acquired by the ADC. Additionally, the offset module allows for in-orbit calculation and updating of the offset.ResultsThe DAQ operates stably in orbit and functions normally, accurately recording the amplitude, position, and arrival time of signals. This capability enables the production of images and energy spectra, which provide robust support for scientific data analysis on the ground.ConclusionThe DAQ has achieved readout and data acquisition for the pnCCD module of the focal plane detector, meeting the requirements of the EP satellite’s FXT payload and operating well in orbit.

The Microchannel X-ray Telescope (MXT) is an innovative compact X-ray instrument on board the SVOM astronomical mission dedicated to the study of transient phenomena such as gamma-ray bursts. During 3 weeks, we have tested the MXT flight model at the Panter X-ray test facility under the nominal temperature and vacuum conditions that MXT will undergo in-flight. We collected data at series of characteristic energies probing the entire MXT energy range, from 0.28 keV up to 9 keV, for multiple source positions with the center of the point spread function (PSF) inside and outside the detector field of view (FOV). We stacked the data of the positions with the PSF outside the FOV to obtain a uniformly illuminated matrix and reduced all data sets using a dedicated pipeline. We determined the best spectral performance of MXT using an optimized data processing, especially for the energy calibration and the charge sharing effect induced by the pixel low energy thresholding. Our results demonstrate that MXT is compliant with the instrument requirement regarding the energy resolution (< 80 eV at 1.5 keV), the low and high energy threshold, and the accuracy of the energy calibration (± 20 eV). We also determined the charge transfer inefficiency ( ∼ 1 0 − 5 ) of the detector and modeled its evolution with energy prior to the irradiation that MXT will undergo during its in-orbit lifetime. Finally, we measured the relation of the energy resolution as function of the photon energy. We determined an equivalent noise charge of 4.9 ± 0.2 e rms − for the MXT detection chain and a Fano factor of 0.131 ± 0.003 in silicon at 208 K, in agreement with previous works. This campaign confirmed the promising scientific performance that MXT will be able to deliver during the mission lifetime.

BackgroundThe 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.MethodsThe FXT conducted functional performance tests in-orbit as planned, including three operating modes of the detector, energy detection range, and energy resolution.ResultsSince 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 3.3 e- .

PurposeThe 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.MethodsThe 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.ResultsThe power-supply and monitoring module operates reliably and performs effectively in orbit, meeting the requirements of the FXT payload on the EP satellite.ConclusionThe 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.

PurposeThe 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.MethodsA 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.ResultsThe thermal control subsystem of FXT is operating properly in-orbit. All component temperatures meet the design requirements.ConclusionAfter 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.