The flight of the Micro-X sounding rocket on July 22, 2018, marked the first operation of transition-edge sensors and their superconducting quantum interference device readouts in space. The instrument combines the microcalorimeter array with an imaging mirror to take high-resolution spectra from extended X-ray sources. The first flight target was the Cassiopeia A supernova remnant. Although a rocket pointing malfunction led to no time on-target, data from the flight were used to evaluate the performance of the instrument and demonstrate the flight viability of the payload. The instrument successfully achieved a stable cryogenic environment, executed all flight operations, and observed X-rays from the on-board calibration source. The flight environment did not significantly affect the performance of the detectors compared with ground operation. The flight provided an invaluable test of the impact of external magnetic fields and the instrument configuration on detector performance. This flight provides a milestone in the flight readiness of these detector and readout technologies, both of which have been selected for future X-ray observatories.

We developed a wideband multi-channel merge-split fast Fourier transform spectrometer (FFTS) using analog-to-digital convertors (ADC) for signal sampling and field-programmable gate arrays (FPGA) for real-time spectrum generation. The FFTS constitutes the backend of the sub-mm wave heterodyne spectroscopy telescope to observe emitted radiations from rotational transitions of CO (J: 2 → 1 and J: 3 → 2) with 50 arc sec angular resolution, aiming to provide the first comprehensive survey of molecular clouds in the Milky Way and nearby galaxies from the northern hemisphere (Hanle, India) at these frequencies. The FFTS provides 8 GHz instantaneous bandwidth at 1.6 MHz spectral resolution (extendable to 0.8 or 0.4 MHz) comprising four channels (spanning 218.898 to 220.898 GHz, 229.038 to 231.038 GHz, 329.087 to 331.087 GHz, and 344.295 to 346.295 GHz frequency bands) belonging to two receiver chains at 230 and 345 GHz operating in a double side band configuration. The channel placement for these four channels is done to cover ¹³CO (J:2 → 1) transition at 220.398 GHz, ¹²CO (J:2 → 1) transition at 230.538 GHz, ¹³CO (J:3 → 2) transition at 330.588 GHz, and ¹²CO (J:3 → 2) transition at 345.796 GHz with 1.5 GHz margin for red-shifts. Spectrometer design is presented along with spectral line profile simulations, hardware configuration, proposed methodology, system specifications, and scalable field-programmable gate arrays (FPGA) implementation architecture. Elements in the instrument design leverage simultaneous multi-channel acquisition for optimized FPGA utilization by merging the channel pair from the sideband separating (2SB) second stage intermediate frequency (IF) mixer during Fourier transform and subsequently splitting the generated spectra. System characterization results are presented, confirming instruments capable of stable spectroscopy with a wide bandwidth (instantaneous 8 GHz with four 2 GHz channels) and high-spectral sampling (1 / 0.5 / 0.25 MHz corresponding to scalable fast Fourier transform length of 4k / 8k / 16k respectively) that provides adequate spectral resolution for the science case. Wide dynamic range (49.3 dB) and fine radiometric resolution required for relative spectroscopic measurements is realized by sampling IF signals with 12-bits ADCs. Variable spectral accumulation time facilitates improvements in the signal to noise ratio proportional to the square root of the number of coherent averaged cycles, covering various target dependent (longer dwell time for a single target) or scanning dependent (e.g., drift scanning mode matching earth’s rotation) dwell time requirements.

The Sunrise Chromospheric Infrared spectroPolarimeter (SCIP) has been developed for the third flight of the Sunrise balloon-borne stratospheric solar observatory. The aim of the SCIP is to reveal the evolution of three-dimensional magnetic fields in the solar photosphere and chromosphere using spectropolarimetric measurements with a polarimetric precision of 0.03% (1σ). Multiple lines in the 770 and 850 nm wavelength bands are simultaneously observed with two 2 k × 2 k CMOS cameras at a frame rate of 31.25 Hz. Stokes profiles are calculated onboard by accumulating the images modulated by a polarization modulation unit, and then compression processes are applied to the two-dimensional maps of the Stokes profiles. This onboard data processing effectively reduces the data rate. SCIP electronics can handle large data formats at high speed. Before the implementation into the flight SCIP electronics, a performance verification of the onboard data processing was performed with synthetic SCIP data that were produced with a numerical simulation modeling the solar atmospheres. Finally, we verified that the high-speed onboard data processing was realized on ground with the flight hardware using images illuminated by natural sunlight or an LED light.

A major source of background for x-ray focal plane detectors in space instrumentation aboard missions, such as Extended Roentgen Survey with an Imaging Telescope Array and Athena Wide Field Imager, is the space radiation environment. High-energy radiations from the environment interact with the spacecraft structure leading to large productions of secondary particles with energies that are detectable in the science region of interest for instrumentation. Reducing the background from these events is vital for the success of many missions. Graded-Z shielding is a common solution to help reduce the instrument background. Layers of materials with decreasing atomic numbers near detectors help reduce the background. Much of the design is determined through iterative simulations to find an optimal solution that meets the requirements for the scientific operation of the instrument. Recent results have indicated an underestimate in the instrument background from the simulations. One hypothesis has been that the simulations do not typically include the impurities in the shielding materials. The work presented investigates the association of impurities in the graded-Z materials and the instrument background spectra. Typically, impurities are not included in material definitions as they can significantly increase computational time. The impurities, percentage loading, and distribution have all been explored and evaluated for an Al-Mo-Be graded-Z shield.

The x-ray detectors on board astrophysics space missions require optical blocking filters that are highly transparent to x-rays. The filter design typically consists of a polymeric film that is a few tens of nanometers thick coated with aluminium. Due to the large size of the filter membrane (from a few tens to a few hundred square centimeters) and the extreme aspect ratio, together with severe loading conditions during launch and different stoichiometries of the polymer that could change its mechanical properties, a characterization study of the employed material is needed. The plane strain bulge test is a well-accepted methodology for the mechanical testing of structures that are less than a micrometer thick, and especially for freestanding membranes. Unfortunately, testing such ultra-thin films is not a simple task due to residual stress and experimental uncertainty at very low pressure. In this work, the elastic properties of an extremely thin (between 45 and 415 nm) membrane made of bare polyimide and coated with aluminium were derived through adopting a combined experimental-numerical methodology based on the bulge test and numerical simulations.

GEOspace X-ray imager (GEO-X) is a small satellite mission aiming at visualization of the Earth’s magnetosphere by X-rays and revealing dynamic couplings between solar wind and the magnetosphere. In-situ spacecraft have revealed various phenomena in the magnetosphere. X-ray astronomy satellite observations recently discovered soft X-ray emissions originating from the magnetosphere. We are developing GEO-X by integrating innovative technologies of a wide field of view (FOV) X-ray instrument and a small satellite for deep space exploration. The satellite combines a Cubesat and a hybrid kick motor, which can produce a large delta v to increase the altitude of the orbit to about 30 to 60 R_E from a relatively low-altitude (e.g., geo transfer orbit) piggyback launch. GEO-X carries a wide FOV (5 × 5 deg) and a good spatial resolution (10 arcmin) X-ray (0.3 to 2 keV) imaging spectrometer using a micro-machined X-ray telescope and a CMOS detector system combined with an optical blocking filter. We aim to launch the satellite around the solar maximum of solar cycle 25.

The Nancy Grace Roman Space Telescope (“Roman”), under development by NASA, will investigate possible causes for the phenomenon of dark energy and detect and characterize extrasolar planets. The 2.4 m space telescope has two main instruments: a wide-field, infrared imager and a coronagraph. The coronagraph instrument (CGI) is a technology demonstrator designed to help bridge the gap between the current state-of-the-art space and ground instruments and future high-contrast space coronagraphs that will be capable of detecting and characterizing Earth-like planets in the habitable zones of other stars. Using adaptive optics, including two high-density deformable mirrors and low- and high-order wavefront sensing and control, CGI is designed to suppress the star light by up to nine orders of magnitude, potentially enabling the direct detection and characterization of Jupiter-class exoplanets. Contrast is the measure of starlight suppression, and high contrast is the chief virtue of a coronagraph. But it is not the only important characteristic: contrast must be balanced against acceptance of planet light. The remaining unsuppressed starlight must also have a stable morphology to allow further estimation and subtraction. To achieve all these goals in the presence of the disturbance and radiation environment of space, the coronagraph must be designed and fabricated as a highly optimized system. The CGI error budget is the top-level tool used to guide the optimization, enabling trades of various competing errors. The error budget is based on an analytical model, which enables rapid calculation and tracking of performance for the numerous and diverse questions that arise in the system engineering process. We outline the coronagraph system engineering approach and the error budget. We then describe in detail the analytical model for direct imaging and spectroscopy and show how it connects to the error budget. We introduce a number of useful ancillary metrics that provide insight into the capabilities of the instrument. Since models always need to be validated, we describe the validation approach for the CGI analytical model.

The Keck Planet Imager and Characterizer (KPIC) is an instrument at the Keck II telescope that enables high-resolution spectroscopy of directly imaged exoplanets and substellar companions. KPIC uses single-mode fibers to couple the adaptive optics system to Keck’s near-infrared spectrometer (NIRSPEC). However, KPIC’s sensitivity at small separations is limited by the leakage of stellar light into the fiber. Speckle nulling uses a deformable mirror (DM) to destructively interfere starlight with itself, a technique typically used to reduce stellar signal on a focal-plane imaging detector. We present the first on-sky demonstration of speckle nulling through an optical fiber with KPIC, using NIRSPEC to collect exposures that measure speckle phase for quasi-real-time wavefront control while also serving as science data. We repeat iterations of measurement and correction, each using at least five exposures (four with DM probes to determine phase and one unprobed exposure to measure the intensity) and taking about 6 min when using 59.0 s exposures, including NIRSPEC overheads. We show a decrease in the on-sky leaked starlight by a factor of 2.6 to 2.8 in the targeted spectral order, at a spatial separation of 2.0 λ / D in K-band. This corresponds to an estimated factor of 2.6 to 2.8 decrease in the required exposure time to reach a given signal-to-noise ratio, relative to conventional KPIC observations. The performance of speckle nulling is limited by instability in the speckle phase: when the loop is opened, the null-depth degrades by a factor of 2 on the timescale of a single phase measurement, which would limit the suppression that can be achieved. Future work includes exploring gradient-descent methods, which may be faster and thereby able to achieve deeper nulls. In the meantime, the speckle nulling algorithm demonstrated in this work can be used to decrease stellar leakage and improve the signal-to-noise of science observations.

Vortex fiber nulling (VFN) is a single-aperture interferometric technique for detecting and characterizing exoplanets separated from their host star by less than a diffracted beam width. VFN uses a vortex mask and single-mode fiber to selectively reject starlight while coupling off-axis planet light with a simple optical design that can be readily implemented on existing direct imaging instruments that can feed light to an optical fiber. With its axially symmetric coupling region peaking within the inner working angle of conventional coronagraphs, VFN is more efficient at detecting new companions at small separations than conventional direct imaging, thereby increasing the yield of on-going exoplanet search campaigns. We deployed a VFN mode operating in K band (2.0 to 2.5 μm) on the Keck Planet Imager and Characterizer (KPIC) instrument at the Keck II Telescope. We present the instrument design of this first on-sky demonstration of VFN and the results from on-sky commissioning, including planet and star throughput measurements and predicted flux-ratio detection limits for close-in companions. The instrument performance is shown to be sufficient for detecting a companion 10³ times fainter than a fifth magnitude host star in 1 h at a separation of 50 mas (1.1 λ / D). This makes the instrument capable of efficiently detecting substellar companions around young stars. We also discuss several routes for improvement that will reduce the required integration time for a detection by a factor >3.

When developing new astronomical instruments, there is a need to perform the characterization of their individual components, especially the detectors, to ensure that their performances comply with the scientific objectives of the instrument. A visible-near infrared (VIS-NIR) facility was developed for the absolute and relative radiometric characterization of space-based detectors at the Royal Belgian Institute for Space Aeronomy (BIRA-IASB). The facility operates from 0.4 to 2.65 μm in an ISO-5 environment. It offers a tunable monochromatic flux with a high level of straylight rejection (^{10 − 8}) and 2% uniformity, over a four-decade range of intensity with adjustable bandwidth. Latency measurements are also possible. Thermalization is offered within a precision of 7 mK between 50 K and 382 K. The ultimate vacuum level of the detector chamber is below 10 ^{− 6} mbar. A robust security system avoids both reaching temperatures outside the operational range of the detector and its electronics, and contamination due to vacuum loss. The facility was already used to characterize the VIS-NIR detectors of the Moons And Jupiter Imaging Spectrometer (MAJIS), one of the instruments on board the Jupiter ICy Moons Explorer (JUICE). The versatility provided by the VIS-NIR facility allows its use for the characterization of other astronomical detectors.

CubeSats provide opportunities for science and technology demonstration missions with low-cost solutions and short project timescales, in particular, for studying gamma-ray bursts (GRBs) in the multi-messenger era. A robust operations strategy for scientific CubeSat projects is key to optimizing the results obtained from the experimental instruments. The Educational Irish Research Satellite-1 (EIRSAT-1) is a 2U CubeSat with three payloads, including a bespoke gamma-ray detector, gamma-ray module (GMOD), developed in-house for the detection of GRBs. The detection and reporting of GRB triggers to the scientific community complicates and drives the mission operational strategy. The operational procedures developed for commissioning and operating GMOD are detailed. The successful operation of EIRSAT-1 will facilitate the detection of ∼15 GRBs / year in low Earth orbit. To increase the likelihood of mission success, the project is following a prototype model philosophy, building, and testing, both an engineering qualification model (EQM) and flight model. The EIRSAT-1 operations manual is the document that will instruct operators in commanding the spacecraft correctly and efficiently throughout the mission lifetime. The operations manual must be refined in parallel to payload development. This two-model philosophy has provided time for the early development of the EIRSAT-1 operations manual with the EQM. The EIRSAT-1 operations manual has undergone incremental updates based on feedback from operational development tests (ODTs), and a version with 35 procedures was frozen prior to the month-long EQM mission test (MT). Specifically, the objective of our work is to validate and refine the operations manual using the EQM MT process. Although the ODTs were effective preparation, the MT process highlighted issues, such as procedures operators found convoluted, and scenarios not yet considered during the initial development stages. Two new procedures were identified, 8 procedures required major updates, 15 required minor updates, and the remaining 12 required no improvements after the MT. The validation process facilitated operator training in mission representative conditions, such as GRB triggering data downlink with GMOD, and the major lessons learned during the development and validation process are presented.

Local Volume Mapper Spectrograph Control Package (LVMSCP) is the software that controls three spectrographs to acquire science spectral data cubes automatically. The software architecture design based on Python 3.9 follows a hierarchical structure of Actors, the unit that controls each piece of hardware. We used the software framework Codified Likeness Utility to implement each Actor. The Actors communicate with each other through RabbitMQ, which implements the Advanced Message Queuing Protocol. The Actor applies asynchronous programming with non-blocking procedures as the three spectrographs should operate simultaneously. For the requirement of incremental code change and management in the collaboration of the developers, we adopted the SDSS Github Action, which supports continuous integration/continuous deployment. As a result, unit testing with Pytest tested the individual components of the software, respectively, and lab testing with LVMSCP provided the spectra data for the spectrograph calibration. The LVMSCP provides the application programming interface to the Robotic Observation Package to fulfill the required scientific survey execution for the spectrographs.

We present an implementation of a channelizer (F-engine) running on a graphics processing unit (GPU). While not the first GPU implementation of a channelizer, we have put significant effort into optimizing the implementation. We are able to process 4 antennas each with 2 Gsample / s, 10-bit dual-polarized input and 8-bit output, on a single commodity GPU. This fully utilizes the available peripheral component interconnect express (PCIe) bandwidth of the GPU. The system is not as optimized for a single high-bandwidth antenna but handles 6.2 Gsample / s, limited by single-core central processing unit (CPU) performance.

In this work, we measured the polarization properties of the X-rays emitted from the X-ray tubes, which were used during the calibration of the instrument onboard Imaging X-ray Polarimetry Explorer (IXPE). X-ray tubes are used as a source of unpolarized X-rays to calibrate the response of the gas pixel detectors to unpolarized radiation. However, even though the characteristic fluorescent emission lines are unpolarized, continuum bremsstrahlung emission can be polarized based on the geometry of the accelerated electrons and emitted photons. Hence, characterizing the contribution of polarized X-rays from bremsstrahlung emission is of interest, also for future measurements. We find that, when accelerated electrons are parallel to the emitted photons, the bremsstrahlung emission is unpolarized, and when they are perpendicular, the polarization increases with energy, as expected from the theoretical predictions. A comparison with the theoretical predictions is also shown.

Modern astronomical polarimeters often require simultaneous operation of multiple instruments over broad wavelength ranges. The 4 m DKIST solar telescope will soon cover 0.38 to 4.6 μm with at least 12 independent narrow band polarimeters, all in quasi-simultaneous operation. Calibration can be efficiently performed over this entire bandpass using our elliptical retarder design, achieved with just two optically contacted MgF₂ crystal retarder pairs. Calibration requires very well-characterized, uniform, defect-free retarders and polarizers. I report here on the successful development of four extremely large aperture (d = 120 mm) optically contacted MgF₂ retarder pairs used to make a DKIST calibrator and a modulator for the Cryo-NIRSP instrument. All four crystal pairs have clear apertures free of defects. New procedures deliver fast axis alignment in the range of 0.1 deg to 0.2 deg post contact bonding. For the calibrator crystals, a new process was developed using deterministic fluid jet polishing driven by retardance mapping to achieve stringent retardance spatial uniformity. I show that transmitted wavefront error is not a sufficient proxy for retardance polishing. Polishing softer MgF₂ retarder crystals required substantial development to simultaneously achieve flatness, roughness, and retardance uniformity. The optical contact bond ensures there are no bonding agents (oils, epoxies) with spectral absorption bands in the entire 0.3 to 6 μm bandpass without any possibility for leaks or degradation. These four crystals will be used in DKIST and Cryo-NIRSP in a 300 W solar beam and are anticipated to mitigate heating, stability, and UV irradiation issues. I use the Berreman calculus to compute retarder depolarization, with >10 % magnitudes found at the shortest wavelengths after including typical crystal optic axis cutting errors and incidence angle variation in converging beams.

Time-domain astronomy is important in the field of modern astronomy, and monitoring observations in the mid-infrared region with 1% photometric accuracy to study the variables and transients is becoming essential. The non-uniformity of the sensitivity caused by the optical characteristics of instruments and differences in the response curves of individual detector pixels degrade photometric accuracy. Therefore, to achieve 1% photometric accuracy, a flat-field correction for the non-uniformity with an accuracy of better than 1% is required. We developed a flat calibration unit (FCU) consisting of a silicon lens, a blackbody source, and two flat folding mirrors. We conducted proof-of-concept tests of the FCU by measuring the accuracy and stability of flat frames obtained using the FCU. The accuracies of the flat frames were 0.23% at 7.7 μm, 0.43% at 9.6 μm, 0.34% at 11.5 μm, and 0.84% at 20.9 μm, which are sufficient to achieve 1% photometric accuracy. The flat frames obtained using the FCU were stable over a period of 29 h within the accuracies of 0.13% at 7.7 μm, 0.12% at 9.6 μm, 0.22% at 11.5 μm, and 0.52% at 20.9 μm, indicating that it is sufficient to obtain flat frames once per night.

The absorption by gas toward background continuum sources informs us about the cosmic density of gas components as well as the hosts responsible for the absorption (galaxies, clusters, and cosmic filaments). Cosmic absorption line distributions are distorted near the detection threshold (S / N ≈ 3) due to true lines being scattered to a lower signal-to-noise (S/N) and false detections occurring at the same S/N. We simulate absorption line distributions in the presence of noise and consider two models for recovery: a parametric fitting of the noise plus a cut-off power law absorption line distribution and a non-parametric fit in which the negative absorption line distribution (emission lines) is subtracted from the positive S/N absorption line distribution (flip and subtract). We show that both approaches work equally well and can use data with S / N ≳ 3 to constrain the fit. For an input of about 100 absorption line systems, the number of systems is recovered to ≈14 % . This investigation examined the O VII X-ray absorption line distribution, but the approach should be broadly applicable for statistically well-behaved data.

The PAlomar Radial Velocity Instrument (PARVI) is a diffraction-limited, high-resolution spectrograph connected by single-mode fiber to the 200 inch Hale telescope at Palomar Observatory. Here, we present on-sky results for HD 189733 obtained during PARVI’s commissioning phase. We first describe the implementation of our spectral extraction and radial velocity (RV) generation codes. Through RV monitoring, we detect the Rossiter–Mclaughlin signal of the transiting planet HD 189733 b. We further detect the presence of water and carbon monoxide in the atmosphere of HD 189733 b via transmission spectroscopy. This work demonstrates PARVI’s high-resolution spectral capabilities at H band and current intra-night Doppler stability of ∼4 to 10 m s ^{− 1} on an early K dwarf. Finally, we discuss the limitations to this work and ongoing efforts to characterize and improve the Doppler performance of PARVI to the design goal of ∼1 m s ^{− 1} for late-type stars.