| 1. |
- Axelsson, Magnus
(författare)
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Hitomi (ASTRO-H) X-ray Astronomy Satellite
- 2018
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Ingår i: Journal of Astronomical Telescopes Instruments and Systems. - 2329-4124 .- 2329-4221. ; 4:2
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Tidskriftsartikel (refereegranskat)abstract
- The Hitomi (ASTRO-H) mission is the sixth Japanese x-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E > 2 keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft x-rays to gamma rays. After a successful launch on February 17, 2016, the spacecraft lost its function on March 26, 2016, but the commissioning phase for about a month provided valuable information on the onboard instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month.
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| 2. |
- Hansen, Jonah T., et al.
(författare)
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Pyxis : a ground-based demonstrator for formation-flying optical interferometry
- 2023
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Ingår i: JOURNAL OF ASTRONOMICAL TELESCOPES INSTRUMENTS AND SYSTEMS. - : SPIE - The International Society for Optics and Photonics. - 2329-4124 .- 2329-4221. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- In the past few years, there has been a resurgence in studies of space-based optical/ infrared interferometry, particularly with the vision to use the technique to discover and characterize temperate Earth-like exoplanets around solar analogs. One of the key technological leaps needed to make such a mission feasible is demonstrating that formation flying precision at the level needed for interferometry is possible. Here, we present Pyxis, a ground-based demonstrator for a future small satellite mission with the aim to demonstrate the precision metrology needed for spacebased interferometry. We describe the science potential of such a ground-based instrument and detail the various subsystems: three six-axis robots, a multi-stage metrology system, an integrated optics beam combiner, and the control systems required for the necessary precision and stability. We conclude by looking toward the next stage of Pyxis: a collection of small satellites in Earth orbit.
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| 3. |
- Leisawitz, David, et al.
(författare)
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Origins Space Telescope: Baseline mission concept
- 2021
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Ingår i: Journal of Astronomical Telescopes, Instruments, and Systems. - 2329-4221 .- 2329-4124. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- The Origins Space Telescope will trace the history of our origins from the time dust and heavy elements permanently altered the cosmic landscape to present-day life. How did galaxies evolve from the earliest galactic systems to those found in the Universe today? How do habitable planets form? How common are life-bearing worlds? To answer these alluring questions, Origins will operate at mid-and far-infrared (IR) wavelengths and offer powerful spectroscopic instruments and sensitivity three orders of magnitude better than that of the Herschel Space Observatory, the largest telescope flown in space to date. We describe the baseline concept for Origins recommended to the 2020 US Decadal Survey in Astronomy and Astrophysics. The baseline design includes a 5.9-m diameter telescope cryocooled to 4.5 K and equipped with three scientific instruments. A mid-infrared instrument (Mid-Infrared Spectrometer and Camera Transit spectrometer) will measure the spectra of transiting exoplanets in the 2.8 to 20 μm wavelength range and offer unprecedented spectrophotometric precision, enabling definitive exoplanet biosignature detections. The far-IR imager polarimeter will be able to survey thousands of square degrees with broadband imaging at 50 and 250 μm. The Origins Survey Spectrometer will cover wavelengths from 25 to 588 μm, making wide-area and deep spectroscopic surveys with spectral resolving power R ∼ 300, and pointed observations at R ∼ 40,000 and 300,000 with selectable instrument modes. Origins was designed to minimize complexity. The architecture is similar to that of the Spitzer Space Telescope and requires very few deployments after launch, while the cryothermal system design leverages James Webb Space Telescope technology and experience. A combination of current-state-of-the-art cryocoolers and next-generation detector technology will enable Origins' natural background-limited sensitivity.
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| 4. |
- Maharana, Siddharth, et al.
(författare)
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WALOP-South: a four-camera one-shot imaging polarimeter for PASIPHAE survey. Paper II - polarimetric modeling and calibration
- 2022
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Ingår i: Journal of Astronomical Telescopes, Instruments, and Systems. - 2329-4221 .- 2329-4124. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The Wide-Area Linear Optical Polarimeter (WALOP)-South instrument is an upcoming wide-field and high accuracy optical polarimeter to be used as a survey instrument for carrying out the Polar-Areas Stellar Imaging in Polarization High-Accuracy Experiment program. Designed to operate as a one-shot four-channel and four-camera imaging polarimeter, it will have a field of view of 35 × 35 arcminutes and will measure the Stokes parameters I, q, and u in a single exposure in the Sloan Digital Sky Survey-r broadband filter. The design goal for the instrument is to achieve an overall polarimetric measurement accuracy of 0.1% over the entire field of view. We present here the complete polarimetric modeling of the instrument, characterizing the amount and sources of instrumental polarization. To accurately retrieve the real Stokes parameters of a source from the measured values, we have developed a calibration method for the instrument. Using this calibration method and simulated data, we demonstrate how to correct for instrumental polarization and obtain 0.1% accuracy in degree of polarization, p. In addition, we tested and validated the calibration method by implementing it on a table-top WALOP like test-bed polarimeter in the laboratory.
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| 5. |
- Maharana, Siddharth, et al.
(författare)
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WALOP-South: a four-camera one-shot imaging polarimeter for PASIPHAE survey. Paper I—optical design
- 2021
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Ingår i: Journal of Astronomical Telescopes, Instruments, and Systems. - 2329-4221 .- 2329-4124.
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Tidskriftsartikel (refereegranskat)abstract
- The Wide-Area Linear Optical Polarimeter (WALOP)-South instrument will be mounted on the 1-m South African Astronomical Observatory telescope in South Africa as part of the Polar-Areas Stellar Imaging Polarization High Accuracy Experiment (PASIPHAE) program to carry out a linear imaging polarization survey of the Galactic polar regions in the optical band. Designed to achieve polarimetric sensitivity of 0.05% across a 35 × 35 arc min field of view (FOV), it will be capable of measuring the Stokes parameters I, q, and u in a single exposure in the R broadband and narrowband filters between 0.5 to 0.7 μm. For each measurement, four images of the full field corresponding to linear polarization angles of 0 deg, 45 deg, 90 deg, and 135 deg in the instrument coordinate system will be created on four detectors from which the Stokes parameters can be found using differential photometry. In designing the optical system, major challenges included correcting for the dispersion introduced by large split angle Wollaston prisms used as analysers and other aberrations from the entire field to obtain imaging quality point spread function (PSF) at the detector. We present the optical design of the WALOP-South instrument which overcomes these challenges and delivers near seeing limited PSFs for the entire FOV.
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| 6. |
- McCulloch, M. A., et al.
(författare)
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Dependence of noise temperature on physical temperature for cryogenic low-noise amplifiers
- 2017
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Ingår i: Journal of Astronomical Telescopes, Instruments, and Systems. - : SPIE-Intl Soc Optical Eng. - 2329-4221 .- 2329-4124. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- We present the results of noise-temperature measurements for four radio astronomy MMIC low-noise amplifiers (LNAs) at physical temperatures from 2 to 160 K. We observe and confirm recent reports that the noise temperature of an LNA exhibits a quadratic dependence with respect to the physical temperature. We are also able to confirm the prediction by Pospieszalski that below a certain physical temperature there is no further significant reduction in noise temperature. We then discuss these results in the context of both the Pospieszalski noise model and some recent Monte-Carlo simulations, which have implied that at very low temperatures, heating of the electron channel above ambient temperature may help to explain the behavior of the drain temperature parameter.
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| 7. |
- Meixner, Margaret, et al.
(författare)
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Origins Space Telescope science drivers to design traceability
- 2021
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Ingår i: Journal of Astronomical Telescopes, Instruments, and Systems. - 2329-4221 .- 2329-4124. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- The Origins Space Telescope (Origins) concept is designed to investigate the creation and dispersal of elements essential to life, the formation of planetary systems, and the transport of water to habitable worlds and the atmospheres of exoplanets around nearby K-and M-dwarfs to identify potentially habitable-and even inhabited-worlds. These science priorities are aligned with NASA's three major astrophysics science goals: How does the Universe work? How did we get here? and Are we alone? We briefly describe the science case that arose from the astronomical community and the science traceability matrix for Origins. The science traceability matrix prescribes the design of Origins and demonstrates that it will address the key science questions motivated by the science case.
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| 8. |
- Wiedner, M.C., et al.
(författare)
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Heterodyne Receiver for Origins
- 2021
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Ingår i: Journal of Astronomical Telescopes, Instruments, and Systems. - 2329-4221 .- 2329-4124. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- The Heterodyne Receiver for Origins (HERO) is the first detailed study of a heterodyne focal plane array receiver for space applications. HERO gives the Origins Space Telescope the capability to observe at very high spectral resolution (R = 107) over an unprecedentedly large far-infrared (FIR) wavelengths range (111 to 617 μm) with high sensitivity, with simultaneous dual polarization and dual-frequency band operation. The design is based on prior successful heterodyne receivers, such as Heterodyne Instrument for the Far-Infrared/Herschel, but surpasses it by one to two orders of magnitude by exploiting the latest technological developments. Innovative components are used to keep the required satellite resources low and thus allowing for the first time a convincing design of a large format heterodyne array receiver for space. HERO on Origins is a unique tool to explore the FIR universe and extends the enormous potential of submillimeter astronomical spectroscopy into new areas of astronomical research.
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| 9. |
- Andersen, Torben, et al.
(författare)
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Image-based wavefront sensing for astronomy using neural networks
- 2020
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Ingår i: Journal of Astronomical Telescopes, Instruments, and Systems. - : SPIE - International Society for Optical Engineering. - 2329-4124. ; 6:3
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Tidskriftsartikel (refereegranskat)abstract
- Motivated by the potential of non-diffraction limited, real-time computational image sharpening with neu7 ral networks in astronomical telescopes, we have studied wavefront sensing with convolutional neural networks basedon a pair of in-focus and out-of-focus point spread functions. By simulation, we generated a large dataset for trainingand validation of neural networks, and trained several networks to estimate Zernike polynomial approximations forthe incoming wavefront. We included the effect of noise, guide star magnitude, blurring by wide band imagining, andbit depth. We conclude that the “ResNet” works well for our purpose, with a wavefront RMS error of 130 nm forr0 = 0.3 m, guide star magnitudes 4–8, and inference time of 8 ms. It can also be applied for closed-loop operation inan adaptive optics system. We also studied the possible use of a Kalman filter or a recurrent neural network and foundthat they were not beneficial to performance of our wavefront sensor
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| 10. |
- Capel, Francesca, et al.
(författare)
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Mini-EUSO data acquisition and control software
- 2019
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Ingår i: JOURNAL OF ASTRONOMICAL TELESCOPES INSTRUMENTS AND SYSTEMS. - : SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS. - 2329-4124. ; 5:4
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Tidskriftsartikel (refereegranskat)abstract
- We present the data acquisition and control software for the operation of the Mini-Extreme Universe Space Observatory (EUSO), a space-based fluorescence telescope for the observation of extensive air showers and atmospheric phenomena. This framework has been extensively tested alongside the development of Mini-EUSO and was finalized ahead of the successful launch of the instrument to the ISS on August 22, 2019. The data acquisition, housekeeping, and subsystem control is achieved using custom-designed front-end electronics based on a Xilinx Zynq XC7Z030 chip interfaced with a PCIe/104 CPU module via the integrated Zynq processing system. The instrument control interface is handled using an object-oriented C++ design, which can be run both autonomously and interactively as required. Although developed for Mini-EUSO, the modular design of both the software and hardware can easily be scaled up to larger instrument designs and adapted to different subsystem and communication requirements. As such, this framework will also be used in the upgrade of the EUSO-TA instrument and potentially for the next EUSO-SPB2 NASA Balloon flight. The software and firmware presented are open source and released with detailed and integrated documentation.
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| 11. |
- Heckmann, Lea, et al.
(författare)
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Gamma-ray burst localization strategies for the SPHiNX hard x-ray polarimeter
- 2019
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Ingår i: JOURNAL OF ASTRONOMICAL TELESCOPES INSTRUMENTS AND SYSTEMS. - : SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS. - 2329-4124. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- SPHiNX is a proposed gamma-ray burst (GRB) polarimeter mission operating in the energy range 50 to 600 keV with the aim of studying the prompt emission phase. The polarization sensitivity of SPHiNX reduces as the uncertainty on the GRB sky position increases. The stand-alone ability of the SPHiNX design to localize GRB positions is explored via Geant4 simulations. Localization at the level of a few degrees is possible using three different routines. This results in a large fraction (>80%) of observed GRBs having a negligible (<5%) reduction in polarization sensitivity due to the uncertainty in localization.
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| 12. |
- Jolivet, Aissa, et al.
(författare)
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L- and M-band annular groove phase mask in lab performance assessment on the vortex opticaldemonstrator for coronagraphic applications
- 2019
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Ingår i: Journal of Astronomical Telescopes, Instruments, and Systems. - 2329-4221. ; 5:2, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Coronagraphy is a high-contrast imaging technique that aims to reduce the blinding glare of a star to detect a potential companion in its close environment. Vortex phase mask coronagraphy is widely recognized as one of the most promising approaches. The vortex optical demonstrator for coronagraphic application (VODCA) is a test bench currently developed at the University of Liège. Its main goal is to optically characterize infrared phase masks, in particular vortex masks. We detail the layout and salient features of VODCA and present the performance of the latest L-band (3575 to 4125 nm) and M-band (4600 to 5000 nm) annular groove phase masks (AGPMs) manufactured by our team. We obtain the highest rejection ratio ever measured for an AGPM at L-band: 3.2 × 103 in a narrowband filter (3425 to 3525 nm) and 2.4 × 103 in a broad L-band filter. By providing measurements close to the intrinsic limit of science-grade AGPMs, VODCA proves to be a step forward in terms of the evaluation of vortex phase masks performance.
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| 13. |
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| 14. |
- Van Der Byl, Andrew, et al.
(författare)
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MeerKAT correlator-beamformer : a real-time processing back-end for astronomical observations
- 2022
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Ingår i: Journal of Astronomical Telescopes, Instruments, and Systems. - 2329-4124. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- The MeerKAT radio telescope consists of 64 Gregorian-offset antennas located in the Karoo in the Northern Cape in South Africa. The antenna system consists of multiple subsystems working collaboratively to form a cohesive instrument capable of operating in multiple modes for defined science cases. We focus on the channelizing subsystem (F-engine), the correlation subsystem (X-engine), and the beamforming subsystem (B-engine). In the wideband instrument mode, the channelizing can produce 1024, 4096, or 32,768 channels with correlation up to 64 antennas. Narrowband mode decomposes sampled bandwidth into 32,768 channels. The F-engine also performs delay compensation, equalization, quantization, and grouping and ordering. The X-engine provides both correlation and beamforming computations (independently). This document is intended to be a stand-alone entity covering the channelizing, correlation, and beamforming processes for the MeerKAT radio telescope. This includes data reception, pre- and post-processing, and data transmission.
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