arXiv subjects

Sarah E. Kay

Publications and source records attributed to Sarah E. Kay.

4 recordsLinked to original sources

arXiv2025

Deep Hα survey of the Coma cluster: The Catalog

We present a deep wide-field narrow-band imaging survey of the local rich and dynamically relaxed Coma cluster of galaxies, carried out with the Wide Field Camera at the Isaac Newton Telescope. The survey covers a region of about 2.5 sq. deg. extending from the core of the cluster out to the infall region over the south-west quadrant of the Coma cluster. The $R$ (6380~Å) and $[$S$\scriptstyle\rm II$$]$ (6725~Å) filters of WFC/INT were used to derive the H$α$+[N{\sc ii}] fluxes and equivalent widths of cluster galaxies distributed over a wide range of environmental conditions. The depth of our imaging observations allows us to measure reliably those properties well down into the dwarf regime in the Coma cluster for the first time. We have detected 124 H$α$ emitting sources with spectroscopically-determined membership, 96 of which have not been detected previously. In this paper, we report on the data analysis process and the methodology we used to measure reliable H$α$ properties, and present the measurement catalogue.

astro-ph.GA↗

arXiv2025

Satellite Underflight Utility for Thermal Sensor Harmonization

Underflight maneuvers provide a unique opportunity to harmonize calibration of on-orbit sensors. Due to their similar sensor technologies, their near-identical transmission profiles, orbital properties and platform operations, the underflight data of Landsat 8 and 9 instruments stand out as a qualifier to test proposed metrics, methods, and the extent over which to compare two independently calibrated sensors across their similar operating bandpasses. This study performed a pixel-to-pixel comparison of thermal imagery of TIRS and TIRS-2 (aboard Landsat 8 and 9, respectively) during their five-day underflight maneuver in November 2021, with the ultimate goal of identifying the key site/scene-selection criteria for a subset of images that are suitable for radiative calibration validation purposes. If a group of near-coincidentally observed images by two identical underflying sensors fail to show consistent Top-of-Atmosphere (TOA) Brightness Temperatures for the same exact geographical locations, then the scenes with those shared properties and/or observing conditions will prove unreliable for cross calibration validation of less-similar underflying sensor pairs. This study demonstrates that near-coincidental images with Root Mean Square Deviations (RMSDs) of less than 5\% between their TOA radiances are optimum candidates for cross-validation of radiative calibration between two independently calibrated sensors. This criterion is shown to be reliable for coincidental acquisitions with a wide range of overlapping area, terrain type, land-to-water fraction and cloud coverage. Important considerations include any time gap between near-coincident acquisitions as well as the application of pixel quality masks. The analysis of the selected underflight scenes demonstrated an agreement between the TIRS on Landsat 8 and 9 to within 0.123 K and 0.066 K for the 10.9um and 12.0um bands respectively.

astro-ph.IM↗

arXiv2025

Readout of Microwave Kinetic Inductance Detector (MKID) Arrays for Habitable Worlds Observatory Using a Polyphase Filterbank Algorithm

The Habitable Worlds Observatory (HWO), a nextgeneration ultraviolet/optical/infrared space telescope, will require detector technologies capable of supporting substantially larger pixel-count arrays than those flown on previous missions. Microwave Kinetic Inductance Detectors (MKIDs) provide a scalable solution through microwave multiplexing and have already been demonstrated in balloon-borne instruments using Field-Programmable Gate Arrays (FPGAs) for real-time signal processing. A central element of MKID readout is the Polyphase Filter Bank (PFB) spectrometer, which converts digitized timedomain signals into finely resolved frequency channels for subsequent analysis. To meet the demands for broader bandwidths and higher spectral resolution driven by emerging science goals, efficient FPGA-based implementations of the PFB are essential. This work presents current results from a fixed-point digital design methodology for deploying the PFB architecture on spacequalified FPGAs. The approach emphasizes efficient resource utilization and numerical precision while satisfying stringent performance constraints, enabling scalable, high-resolution spectral processing for future space observatories and remote sensing applications.

astro-ph.IM↗

arXiv2025

Development of Space Qualified Signal Processing Readout Electronics for HabWorlds and Origins Space Telescope Detector and Arrays

The Habitable Worlds Observatory (HWO) -- a flagship ultraviolet/optical/infrared space telescope recommended by the National Academies' Pathways to Discovery in Astronomy and Astrophysics -- will require detector technologies capable of supporting significantly larger pixel-count arrays than previous missions. Microwave Kinetic Inductance Detectors (MKIDs), naturally suited to microwave multiplexing readout, are already in use across several balloon-borne missions with FPGA based systems. To transition this capability to space, we are developing a radiation-hardened detector readout system that builds directly on the technical and environmental requirements defined by the PRIMA mission. PRIMA serves as a critical pathfinder, informing the radiation tolerance, resource constraints, and on-board processing capabilities needed for HWO. In this work, we present our current results on algorithm implementation, hardware architecture, and firmware development using the radiation-hardened AMD Kintex Ultrascale FPGA, aligning with PRIMA's stringent specifications to ensure compatibility with future space-based observatories like HWO.

astro-ph.IM↗