arXiv subjects

F. Elio Angile

Publications and source records attributed to F. Elio Angile.

6 recordsLinked to original sources

arXiv2026

Laser Metrology for Precision Alignment of Transmission Gratings in the REDSoX Soft X-ray Polarimeter

The Rocket Experiment Demonstration of a Soft X-ray Polarimeter (REDSoX) is a NASA sounding-rocket mission designed to perform the first astrophysical spectropolarimetry in the 0.2-0.4 keV energy band. The instrument uses critical-angle transmission (CAT) gratings to disperse incident X-rays onto laterally graded multilayer (LGML) mirrors, requiring 48 individual gratings to be co-aligned to within 6 arcminutes in yaw, pitch, and roll. To support the systematic assembly of the grating array, we adapted a scanning laser-reflection metrology technique in which normal-reflected, angled-reflected, and diffracted ultraviolet laser beams are measured using three position-sensitive detectors (PSDs). Changes in the measured beam positions are used to reconstruct the local yaw, pitch, and roll of each grating and provide real-time feedback during mechanical adjustment. We demonstrate the system using a prototype miniature grating structure containing two gratings. Following co-alignment, the assembly underwent a flight-level random-vibration test followed by a qualification-level sine sweep. Measurements obtained before and after testing showed that the relative grating orientations were retained to within 1 arcminute, less than 17% of the REDSoX co-alignment tolerance. This work establishes a reproducible and scalable approach to the assembly and verification of large transmission-grating arrays for REDSoX and future X-ray spectroscopic instruments.

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arXiv2026

Design and testing progress towards the first flight of the rocket experiment demonstration of a Soft X-ray Polarimeter (REDSoX)

The Rocket Experiment Demonstration of a Soft X-ray Polarimeter (REDSoX) is a NASA-funded, sounding rocket mission. The rocket payload will measure polarization strength and direction as a function of energy in the 0.2-0.4 keV band, providing complementary measurements to those made by IXPE in the 2-8 keV band. The first flight, scheduled for 2028, will provide a technology demonstration of our polarimeter concept, which utilizes an aligned system of a focusing optic, Critical-Angle Transmission (CAT) gratings, Laterally Graded Multilayer (LGML) mirrors, and Charge Coupled Device (CCD) detectors to measure polarization. We will describe the design of the instrument post-critical design review, the status of flight hardware testing, and payload assembly.

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arXiv2026

SuperFIRE: Concept evolution of a seeing-limited broadband spectrograph for the GMT

We are developing the SuperFIRE concept, which builds on the heritage of the FIRE spectrograph at Magellan, as a broadband (about 340 nm to 2.5 um) intermediate resolution (R=10,000) single-shot natural seeing spectrograph for the Giant Magellan Telescope (GMT) with support from the Kavli Foundation. This single-object spectrograph is envisioned as a first-light instrument that can operate in natural seeing and grow in long-term capability as the telescope and adaptive optics systems mature. Here we discuss how the science cases and design have evolved since the concept was initially conceived and presented at SPIE in Edinburgh ten years ago. The primary drivers for the design changes are fast follow-up of faint transients and multi-messenger events, and complementarity to JWST observations in the infrared. By leveraging fast low-noise detectors and modern fabrication techniques we expect high throughput and low scatter that delivers sky limited performance in a few minutes of integration time for fast response and deep integrations. SuperFIRE will operate as a practical point-and-shoot follow-up spectrograph thanks to a versatile standard configuration that needs minimal observing or planning overheads and is insensitive to atmospheric conditions.

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arXiv2026

An eclipsing 8.56 minute orbital period mass-transferring binary

We report the discovery of ATLAS J101342.5-451656.8 (hereafter ATLAS J1013-4516), an 8.56 minute orbital period mass transferring AM Canum Venaticorum binary with mean Gaia magnitude G=19.51. The system was identified via periodic variability in Asteroid Terrestrial-impact Last Alert System light curves of Gaia white dwarf candidates. Follow-up spectroscopy with the Large Lenslet Array Magellan Spectrograph reveals a helium dominated accretion disk, while high speed ULTRACAM photometry shows pronounced primary and secondary eclipses. We construct a decade long orbital timing baseline using ATLAS and Gaia survey photometry together with high speed observations from ULTRACAM on the NTT and proto Lightspeed on the Magellan Clay telescope. From this baseline we measure an orbital period derivative Pdot = -1.60 +/- 0.07 x 10^-12 seconds per second. Interpreted in the context of stable mass transfer, the magnitude and sign of Pdot indicate orbital evolution governed by the interplay between gravitational wave driven angular momentum losses and mass transfer, directly probing the donor star structural response to mass loss. Assuming angular momentum loss dominated by gravitational radiation, we constrain the component masses and infer the characteristic gravitational wave strain. We predict a four year Laser Interferometer Space Antenna signal to noise ratio greater than 10, establishing ATLAS J1013-4516 as a strong prospective space based gravitational wave source that probes long term orbital evolution in the mass transferring regime.

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arXiv2025

The high-speed X-ray camera on AXIS: design and performance updates

AXIS, a Probe mission concept now in a Phase A study, will provide transformative studies of high-energy astrophysical phenomena thanks to its high-resolution X-ray spectral imaging. These capabilities are enabled by improvements to the mirror design that greatly increase the X-ray throughput per unit mass; and to the detector system, which operates more than an order of magnitude faster than heritage instruments while maintaining excellent spectral performance. We present updates to the design of the AXIS High-Speed Camera, a collaborative effort by MIT, Stanford University, the Pennsylvania State University, and the Southwest Research Institute. The camera employs large-format MIT Lincoln Laboratory CCDs that feature multiple high-speed, low-noise output amplifiers and an advanced single-layer polysilicon gate structure for fast, low-power clock transfers. A first lot of prototype CCID100 CCDs has completed fabrication and will soon begin X-ray performance testing. The CCDs are paired with high-speed, low-noise ASIC readout chips designed by Stanford to provide better performance than conventional discrete solutions at a fraction of the power consumption and footprint. Complementary Front-End Electronics employ state-of-the-art digital video waveform capture and advanced signal processing to further deliver low noise at high speed. The Back-End Electronics provide high-speed identification of candidate X-ray events and transient monitoring that relays fast alerts of changing sources to the community. We highlight updates to our parallel X-ray performance test facilities at MIT and Stanford, and review the current performance of the CCD and ASIC technology from testing of prototype devices. These measurements achieve excellent spectral response at the required readout rate, demonstrating that we will meet mission requirements and enable AXIS to achieve world-class science.

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arXiv2025

Characterization of the Teledyne COSMOS Camera: A Large Format CMOS Image Sensor for Astronomy

The Teledyne COSMOS-66 is a next-generation CMOS camera designed for astronomical imaging, featuring a large-format sensor ($8120 \times 8120$ pixels, each $10 \mu m$), high quantum efficiency, high frame rates, and a correlated multi-sampling mode that achieves low read noise. We performed a suite of bench-top and on-sky tests to characterize this sensor and analyze its suitability for use in astronomical instruments. This paper presents measurements of linearity, conversion gain, read noise, dark current, quantum efficiency, image lag, and crosstalk. We found that the sensor exhibits nonlinear response below 5% of saturation. This nonlinearity is plausibly attributable to the trapping of electrons in each pixel. We developed and implemented a pixel-by-pixel nonlinearity correction, enabling accurate photometric measurements across the dynamic range. After implementing this correction, operating in the correlated multi-sampling mode, the sensor achieved an effective read noise of $2.9 e^-$ and dark current of $0.12 e^-/pix/s$ at $-25^\circ C$. The quantum efficiency exceeded 50% from 250 nm to 800 nm, peaking at 89% at 600 nm. We observed significant optical crosstalk between the pixels, likely caused by photoelectron diffusion. To demonstrate the sensor's astronomical performance, we mounted it on the WINTER 1m telescope at Palomar Observatory. These tests confirmed that the linearity calibration enables accurate stellar photometry and validated our measured noise levels. Overall, the COSMOS-66 delivers similar noise performance to large-format CCDs, with higher frame rates and relaxed cooling requirements. If pixel design improvements are made to mitigate the nonlinearity and crosstalk, then the camera may combine the advantages of low-noise CMOS image sensors with the integration simplicity of large-format CCDs, broadening its utility to a host of astronomical science cases.

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