The Astro2020 decadal survey designated a large ultraviolet (UV)/optical/infrared strategic mission, the Habitable Worlds Observatory (HWO), as the top priority for space-based astronomy in the coming decade. HWO will pursue an ambitious program of exoplanetary discovery/characterization and cosmic origin astrophysics. The decadal survey report recognized that many of HWO's galactic ecosystem, exoplanet, and stellar science goals require high-throughput imaging and spectroscopy at ultraviolet through optical wavelengths (100 to 1000 nm). Early conceptual designs for the UV spectrograph on HWO are based on the LUVOIR and HabEx concept study reports, with a multi-object spectrograph incorporating multiple grating modes at the core of the instrument, and a high-resolution echelle mode and UV imager also under study (collectively referred to as the HWO UltraViolet Instrument, UVI). Recently, the HWO project office has also initiated the study of a secondary integral-field spectrograph. Taken together, the HWO UV spectrographs require gratings of several types spanning from low-resolution, low-blaze-angle modes to the highest-resolution echelle types. It is necessary to develop advanced, aberration-correcting, high-efficiency, low-scatter diffraction gratings to support HWO's need for a wide range of grating characteristics. These efforts leverage recent APRA and SAT programs that developed viable fabrication techniques for improving echelle gratings, realizing ultralow blaze angles, creating custom groove shapes on curved surfaces, and infusing these technologies into suborbital demonstration missions. The continuation of these studies will increase the performance and technology readiness level of UV gratings through improved fabrication processes and performance verification, thus directly addressing top-priority technology gaps. In addition, the gratings will be studied for incorporation into intermediate-scale missions for demonstration in a mission framework (e.g., class D) that exists between the suborbital and HWO level.
", "doi": "10.1117/1.jatis.12.4.041021", "issn": "2329-4124", "publisher": "SPIE-Intl Soc Optical Eng", "publication": "Journal of Astronomical Telescopes, Instruments, and Systems", "publication_date": "2026-10", "series_number": "04", "volume": "12", "issue": "04", "pages": "041021" }, { "id": "authors:gcs78-jyc76", "collection": "authors", "collection_id": "gcs78-jyc76", "cite_using_url": "https://authors.library.caltech.edu/records/gcs78-jyc76", "type": "article", "title": "Kinematically Complex Circumgalactic Gas Around a Low-mass Galaxy: Filamentary Inflow and Counterrotation in J0910b", "author": [ { "family_name": "Lin", "given_name": "Zeren", "orcid": "0009-0001-7405-1228", "clpid": "Lin-Zeren" }, { "family_name": "Martin", "given_name": "D. Christopher", "orcid": "0000-0002-8650-1644", "clpid": "Martin-D-Christopher" }, { "family_name": "Matuszewski", "given_name": "Mateusz", "orcid": "0000-0003-2821-1750", "clpid": "Matuszewski-Mateusz" }, { "family_name": "Neill", "given_name": "James D.", "orcid": "0000-0002-0466-1119", "clpid": "Neill-James-D" }, { "family_name": "Miles", "given_name": "Drew M.", "orcid": "0000-0001-5982-0060", "clpid": "Miles-Drew-M" }, { "family_name": "Picouet", "given_name": "Vincent", "orcid": "0009-0005-1425-3601", "clpid": "Picouet-Vincent" }, { "family_name": "Prusinski", "given_name": "Nikolaus Z.", "orcid": "0000-0001-5847-7934", "clpid": "Prusinski-Nikolaus-Z" }, { "family_name": "Hoadley", "given_name": "Keri", "orcid": "0000-0002-8636-3309" }, { "family_name": "McGurk", "given_name": "Rosalie" } ], "abstract": "We present the first detailed, spatially resolved study of the circumgalactic medium (CGM) surrounding the low-mass, low-redshift star-forming galaxy J0910b (SDSS J091458.61+110845.1; M\u22c6 ∼ 109.2 M\u2299, z = 0.096), focusing on its gas dynamics, ionization mechanisms, and kinematics. J0910b is the lowest-mass galaxy in our low-redshift CGM survey using the Keck Cosmic Web Imager (KCWI). Using KCWI integral field spectroscopy and CLOUDY modeling, we map the ionization structure and velocity field of the CGM through Hα, [O III] λ5007, and [O II] λλ3727, 3729 emission. We detect a predominantly cool (T ∼ 104 K) ionized halo extending to ∼35 kpc (∼0.35 Rvir), with a complex structure including a counterrotating component and two filamentary inflows. The counterrotating CGM contains ∼7.4 × 109 M\u2299 of ionized gas—nearly 5 times the stellar mass—and exhibits a positive radial metallicity gradient, rising from 0.2 Z\u2299 at 9 kpc to 0.65 Z\u2299 at 16 kpc. Velocity dispersion maps reveal a shell-like structure near the interstellar medium-CGM interface, suggesting feedback-driven outflows that redistributed enriched gas. In contrast, the filaments show low metallicities (∼0.07 Z\u2299), high specific angular momentum (j ∼ 3.7 × 103 kpc km s−1), and an accretion rate of 0.05 M\u2299 yr−1, consistent with an intergalactic origin. Together, these components reveal a dynamically rich CGM. The counterrotating gas dominates the halo’s mass, accounts for ∼33% of the cosmic baryon budget, and must be continuously replenished (tcool ∼ 0.3–2 Myr). These results suggest a long-lived, regulated CGM that governs star formation through angular momentum exchange and gas recycling.
\nThe National Aeronautics and Space Administration (NASA) Great Observatories Maturation Program is a development plan to efficiently and effectively develop large, strategic astrophysics missions. Suborbital rocket and balloon programs have long been a key development tool for enabling large missions in NASA astrophysics. We review the significance of these suborbital missions in the preceding decades to demonstrate their contributions to the Great Observatories Maturation Program for the Habitable Worlds Observatory and beyond. We show that suborbital instruments have obtained science observations of astrophysical sources across the electromagnetic spectrum, matured high-priority component technologies, and served as a training ground for principal investigators of explorer-class astrophysics satellites. A brief discussion of emerging CubeSat and SmallSat missions and their place in the NASA astrophysics portfolio is also provided.
", "doi": "10.1117/1.jatis.11.4.042220", "issn": "2329-4124", "publisher": "SPIE-Intl Soc Optical Eng", "publication": "Journal of Astronomical Telescopes, Instruments, and Systems", "publication_date": "2025-07", "series_number": "4", "volume": "11", "issue": "4", "pages": "042220" }, { "id": "authors:5fd2v-4m814", "collection": "authors", "collection_id": "5fd2v-4m814", "cite_using_url": "https://authors.library.caltech.edu/records/5fd2v-4m814", "type": "article", "title": "Delta-doped electron-multiplying charge-coupled device for photon-starved ultraviolet astronomy: modeling, performance, trade-offs, and prospects for future upgrades", "author": [ { "family_name": "Picouet", "given_name": "Vincent", "orcid": "0009-0005-1425-3601", "clpid": "Picouet-Vincent" }, { "family_name": "Kyne", "given_name": "Gillian", "clpid": "Kyne-Gillian" }, { "family_name": "Hamden", "given_name": "Erika", "orcid": "0000-0002-3131-7372" }, { "family_name": "Valls-Gabaud", "given_name": "David" }, { "family_name": "Miles", "given_name": "Drew M.", "orcid": "0000-0001-5982-0060", "clpid": "Miles-Drew-M" }, { "family_name": "Khan", "given_name": "Aafaque", "orcid": "0000-0002-1244-0295" }, { "family_name": "Lin", "given_name": "Zeren", "orcid": "0009-0001-7405-1228", "clpid": "Lin-Zeren" }, { "family_name": "Nikzad", "given_name": "Shouleh", "clpid": "Nikzad-Shouleh" }, { "family_name": "Vibert", "given_name": "Didier", "orcid": "0009-0008-0607-631X" }, { "family_name": "Martin", "given_name": "D. Christopher", "orcid": "0000-0002-8650-1644", "clpid": "Martin-D-Christopher" } ], "abstract": "In the pursuit of observing fainter astronomical sources and phenomena, a significant challenge in detector development lies in ensuring that these devices can detect each individual photon they receive. By amplifying each incoming photon by several orders of magnitude, electron-multiplying charge-coupled devices (EMCCDs) offer a promising solution to meet this challenge. Although these detectors boast impressive potential, they can be intricate, requiring precise optimization and fine-tuning of their parameters to unlock their full capabilities in the photon-starved regime. The Faint Intergalactic-medium Redshifted Emission Balloon (FIREBall-2) is a stratospheric project that aims to detect and map the low surface brightness environment of galaxies in the ultraviolet (UV) at z ~ 0.7. As a technology demonstrator for photon-starved astronomy and to advance the technology readiness level of UV EMCCDs, the instrument uses a Teledyne-e2v (T-e2v) EMCCD delta-doped by the Jet Propulsion Laboratory, combined with a NüVü controller. To analyze the detector data and retrieve the device noise contributions, we developed a comprehensive EMCCD model along with DS9 analysis tools to compare the model with the actual data under diverse operating conditions. This allowed us to examine the current performance and limitations of these devices both on the ground and in the stratospheric environment, to unravel the intricacies of these detectors. In addition, we will discuss the development and implementation of an exposure time calculator designed to optimize the end-to-end signal-to-noise ratio under diverse conditions and analyze the different trade-offs associated with such devices. This will be used to explore some EMCCD-related issues encountered on FIREBall-2 and present some recent and potential future upgrade strategies (controller upgrade, red-blocking filter, over-spill register implementation, etc.) to mitigate them.
", "doi": "10.1117/1.jatis.11.1.011206", "issn": "2329-4124", "publisher": "SPIE-Intl Soc Optical Eng", "publication": "Journal of Astronomical Telescopes, Instruments, and Systems", "publication_date": "2025-01-02", "series_number": "01", "volume": "11", "issue": "01", "pages": "011206" } ]