Sazuna/UAT_keywords huggingface dataset:
A Classic Nonlinearity Correction Algorithm for Detectors Read Out Up-the-ramp. We derive an algorithm for computing a classic nonlinearity correction—applicable to constant and uniform illumination—in the presence of read noise and photon noise. The algorithm operates simultaneously on many nondestructive ramps at a range of count rates and directly computes the function transforming measured counts into linearized counts. We also compute χ2 for the corrected ramps, enabling the user to identify the polynomial degree beyond which χ2 ceases to improve significantly. The computational cost of our algorithm is linear in the number of reads and ramps, reaching ∼100 hr to derive a correction for all 4096 × 4096 pixels of a Hawaii-4 RG detector from 186 illuminated 55-read ramps on a 2023 Macbook Pro laptop (≍10,000 reads per pixel). We identify a potential source of bias in the nonlinearity correction when combining ramps of very different illuminations, together with effective mitigations. We apply our algorithm to a random set of pixels from the Roman Space Telescope's Wide Field Instrument. We find that a ≥9th order nonlinearity correction is needed, at which point χ2 is close to its theoretically expected value and beyond which χ2 improves little with increasing polynomial order. Python software implementing our algorithm is available at https://github.com/RomanSpaceTelescope/SOCReferenceFileCode.

Keywords: Astronomical detectors, Astronomical instrumentation
Computing the Electronic Gain for Detectors Read Out Up-the-ramp. The electronic gain—the conversion between photoelectrons on a pixel and the digital number recorded to disk—gives physical units to an astronomical image and sets the relation between pixel value and photon noise. This paper presents a new, likelihood-based approach to derive the gain from images taken up-the-ramp, where the detector is read out nondestructively many times before being reset. Our method makes full use of the individual reads assuming an ideal detector subject to photon noise and Gaussian read noise. We extend the method to account for slight nonlinearities in the relation between photoelectrons and measured counts. We demonstrate that our likelihood-based approach provides a consistent (i.e., asymptotically correct) and nearly unbiased estimator of the gain both with and without fitting for nonlinearity. Finally, we apply this approach to a single detector from the Wide-Field Instrument on the Roman Space Telescope, and show how pixel-to-pixel gain variations describe much of the variations in pixel response seen in flatfield images. Code to compute gain and regenerate figures in this paper is available at https://github.com/RomanSpaceTelescope/SOCReferenceFileCode.

Keywords: Astronomical detectors, Astronomical instrumentation
The Dynamic Eclipse Broadcast Initiative Software Development for Data Collection, Processing and Uploading During the 2024 April 8th, Total Solar Eclipse. The first phase of the Dynamic Eclipse Broadcast (DEB) Initiative experiment equipped, trained and supported 82 volunteer citizen science teams across North America for white-light imaging of the 2024 April 8th, total solar eclipse for coronal observation and STEM outreach. To ensure the teams obtained consistent scientific quality data with their identical hardware, DEB researchers developed a software package incorporating SharpCap scripting and Planetary System Stacker post-processing to automate the capture, processing and uploading of solar images during partial and total phases of the eclipse. This effort produced an open-source solar astrophotography software package that includes Planetary System Stacker post-processing automation, almost half a terabyte of scientific quality solar images from the April 8th eclipse and 1.5 billion media impressions from 2024 April 8th to 10th.

Keywords: Automated telescopes, Eclipses
The Role of Ammonia in the Distribution of Volatiles in the Primordial Hydrosphere of Europa. The presence of a hydrosphere on Europa raises questions about its habitability, and studies of its volatile inventory can provide insight into its formation process. Different scenarios suggest that Europa's volatiles could be derived from cometary ices or devolatilized building blocks. The study of post-accretion processes—in particular, the "open-ocean" phase that likely occurred before the formation of the icy crust—is crucial to distinguishing these origins, as this phase is likely to have influenced the volatile inventory. The abundance of ammonia in Europa's building blocks is also crucial for understanding the composition of its ocean and primordial atmosphere. We aim to investigate the ocean–atmosphere equilibrium during the post-accretion period by varying the ammonia fraction in the atmosphere. Our model evaluates the vapor–liquid equilibrium of water and volatiles, as well as the chemical equilibrium within the ocean, to study Europa's early hydrosphere. We explore two initial conditions: one in which Europa's hydrosphere originates from comet-like building blocks, and another in which it forms in equilibrium with a thick-and-CO2-rich atmosphere. In both scenarios, the initial ratio of accreted CO2 to NH3 determines the magnitude of their partial pressures in Europa's early atmosphere. If this ratio exceeds a certain threshold (set to 10‑4 in this study), the atmosphere will be CO2-rich; otherwise, it will be CO2-depleted, by multiple orders of magnitude. Overall, our work provides an initial assessment of the distribution of primordial volatiles in Europa's primitive hydrosphere and provides a baseline for interpreting data from the upcoming Europa Clipper mission.

Keywords: Natural satellite formation, Ocean-atmosphere interactions, Europa, Planetary science, Galilean satellites
Early Solar System Turbulence Constrained by High Oxidation States in the Oldest Noncarbonaceous Planetesimals. Early solar system (SS) planetesimals constitute the parent bodies of most meteorites investigated today. Nucleosynthetic isotope anomalies of bulk meteorites have revealed a dichotomy between noncarbonaceous (NC) and carbonaceous (CC) groups. Planetesimals sampling NC and CC isotopic signatures are conventionally thought to originate from the "dry" inner disk and volatile-rich outer disk, respectively, with their segregation enforced by a pressure bump close to the water–ice sublimation line, possible tied to Jupiter's formation. This framework is challenged by emerging evidence that the oldest NC planetesimals (i.e., the iron meteorites parent bodies (IMPBs)) were characterized by far higher oxidation states than previously imagined, suggesting abundant (  few weight percent) liquid water in their interiors prior to core differentiation. In this paper, we employ a model for a degassing icy planetesimal (heated by 26Al decay) to map the conditions for liquid water production therein. Our work culminates in threshold characteristic sizes for pebbles composing the said planetesimal, under which water–ice melting occurs. Adopting a model for a disk evolving under both turbulence and magnetohydrodynamic disk winds, and assuming pebble growth is fragmentation limited, we self-consistently translate the threshold pebble size to lower limits on early SS turbulence. We find that if NC IMPBs were "wet," their constituent pebbles must have been smaller than a few centimeters, corresponding to typical values of the Shakura–Sunyaev α  ν  turbulence parameter in excess of 10‑3. These findings argue against a quiescent SS disk (for &lt;10 au), are concordant with astronomical constraints on protoplanetary disk turbulence, and suggest pebble accretion played a secondary role in building our rocky planets.

Keywords: Solar system, Protoplanetary disks, Planetesimals, Meteorites, Planet formation
The Volatile Composition and Activity Evolution of Main-belt Comet 358P/PANSTARRS. We report the detection of water vapor associated with main-belt comet 358P/PANSTARRS on UT 2024 January 8─9 using the NIRSPEC instrument on board JWST. We derive a water production rate of   molecules s−1, marking only the second direct detection of sublimation products of any kind from a main-belt comet, after 238P/Read. Similar to 238P, we find a remarkable absence of hypervolatile species, finding   molecules s−1, corresponding to  %. Upper limits on CH3OH and CO emission are also estimated. Photometry from ground-based observations shows that the dust coma brightened and faded slowly over ∼250 days in 2023─2024, consistent with photometric behavior observed in 2012─2013, but also indicates a ∼2.5× decline in the dust production rate between these two periods. Dynamical dust modeling shows that the coma's morphology as imaged by JWST's NIRCam instrument on 2023 November 22 can be reproduced by asymmetric dust emission from a nucleus with a midrange obliquity (∊ ∼ 80°) with a steady-state mass-loss rate of ∼0.8 kg s−1. Finally, we find similar Af ρ-to-gas ratios of   for 358P and   for 238P, suggesting that Af ρ could serve as an effective proxy for estimating water production rates in other active main-belt comets. The confirmation of water vapor outgassing in both main-belt comets observed by JWST to date reinforces the use of recurrent activity near perihelion as an indicator of sublimation-driven activity in active asteroids.

Keywords: Main belt asteroids, Comets, Small Solar System bodies, Main-belt comets
Polycyclic Aromatic Hydrocarbons as an Extraterrestrial Atmospheric Technosignature. Polycyclic aromatic hydrocarbons (PAHs) are prevalent in the Universe and interstellar medium but are primarily attributed to anthropogenic sources on Earth, such as fossil fuel combustion and firewood burning. Drawing upon the idea of PAHs being suitable candidates for technosignatures, we investigate the detectability of those PAHs that have available absorption cross sections in the atmospheres of Earth-like exoplanets (orbiting G-type stars at a distance of 10 pc) with an 8 m mirror of the Habitable Worlds Observatory (HWO). Specifically, we focus on Naphthalene, Anthracene, Phenanthrene, and Pyrene. Our simulations indicate that under current-Earth-like conditions, detecting PAH signatures between 0.2 and 0.515 μm is infeasible. To account for the historical decline in PAH production post the industrial revolution, we explore varying PAH concentrations to assess instrumental capabilities of detecting civilizations resembling modern Earth. We also evaluate telescope architectures (6 m, 8 m, and 10 m mirror diameters) to put our results into the context of the future HWO mission. With these four molecules, PAH detection remains infeasible, even at concentrations 10 times higher than current levels. While larger mirrors provide some advantages, they fail to resolve the spectral signatures of these molecules with significant signal-to-noise ratios. The UV absorption features of PAHs—caused by π-orbital → π*-orbital electronic transitions—serve as valuable markers, due to their distinct and detectable nature, preserved by the aromatic stability of PAHs. Additional lab measurements are necessary to gather absorption cross-sectional data beyond UV for more abundant PAHs. This may help further in improving the detectability of these molecules.

Keywords: Exoplanet atmospheric composition , Technosignatures, Exoplanet atmospheres
Earth-like Exoplanets in Spin─Orbit Resonances: Climate Dynamics, 3D Atmospheric Chemistry, and Observational Signatures. Terrestrial exoplanets around M- and K-type stars are important targets for atmospheric characterization. Such planets are likely tidally locked with the order of spin─orbit resonances (SORs) depending on eccentricity. We explore the impact of SORs on 3D atmospheric dynamics and chemistry, employing a 3D coupled climate-chemistry model to simulate Proxima Centauri b in 1:1 and 3:2 SORs. For a 1:1 SOR, Proxima Centauri b is in the Rhines rotator circulation regime with dominant zonal gradients (global mean surface temperature 229 K). An eccentric 3:2 SOR warms Proxima Centauri b to 262 K with gradients in the meridional direction. We show how a complex interplay between stellar radiation, orbit, atmospheric circulation, and (photo)chemistry determines the 3D ozone distribution. Spatial variations in ozone column densities align with the temperature distribution and are driven by stratospheric circulation mechanisms. Proxima Centauri b in a 3:2 SOR demonstrates additional atmospheric variability, including daytime─nighttime cycles in water vapor of +55% to −34% and ozone (±5.2%) column densities and periastron─apastron water vapor cycles of +17% to −10%. Synthetic emission spectra for the spectral range of the Large Interferometer For Exoplanets fluctuate by up to 36 ppm with the orbital phase angle for a 1:1 SOR due to 3D spatial and temporal asymmetries. The homogeneous atmosphere for the 3:2 SOR results in relatively constant emission spectra and provides an observational discriminant from the 1:1 SOR. Our work emphasizes the importance of understanding the 3D nature of exoplanet atmospheres and associated spectral variations to determine habitability and interpret atmospheric spectra.

Keywords: Atmospheric composition, Atmospheric dynamics, Exoplanet atmospheres, Chemical kinetics
Resolved Convection in Hydrogen-rich Atmospheres. In hydrogen-rich atmospheres with low mean molecular weight (MMW), an air parcel containing a higher-molecular-weight condensible can be negatively buoyant even if its temperature is higher than the surrounding environment. This should fundamentally alter the dynamics of moist convection, but the low-MMW regime has previously been explored primarily via 1D theories that cannot capture the complexity of moist turbulence. Here, we use a 3D cloud-resolving model to simulate moist convection in atmospheres with a wide range of background MMWs and confirm that a humidity threshold for buoyancy reversal first derived by T. Guillot coincides with an abrupt change in tropospheric structure. Crossing the "Guillot threshold" in near-surface humidity causes the dry (subcloud) boundary layer to collapse and be replaced by a very cloudy layer with a temperature lapse rate that exceeds the dry adiabatic rate. Simulations with reduced surface moisture availability in the lower atmosphere feature a deeper dry subcloud layer, which allows the superadiabatic cloud layer to remain aloft. Our simulations support a potentially observable systematic trend toward increased cloudiness for atmospheres with near-surface moisture concentrations above the Guillot threshold. This should apply to H2O and potentially to other condensible species on hotter worlds. We also find evidence for episodic convective activity and associated variability in cloud cover in some of our low-MMW simulations, which should be investigated further with global-scale simulations.

Keywords: Planetary atmospheres, Atmospheric clouds
Lucy L'Ralph In-flight Calibration and Results at (152830) Dinkinesh. The L'Ralph instrument is a key component of NASA's Lucy mission, intended to provide spectral image data of multiple Jupiter Trojans. The instrument operates from ∼0.35 to 4 μm using two focal plane assemblies: a 350–950 nm multispectral imager, Multi-spectral Visible Imaging Camera (MVIC), and a 0.97–4 μm imaging spectrometer, Linear Etalon Imaging Spectral Array (LEISA). Instrument calibration was established through ground testing before launch and has been monitored during cruise utilizing internal calibration sources and stellar targets. In-flight data have shown that the instrument thermal performance is exceeding expectations, allowing for early updates to LEISA radiometric and pointing calibrations. MVIC radiometric performance remains stable more than 3 yr since launch. The serendipitous identification of a new flyby target, (152830) Dinkinesh, allowed testing of instrument performance and interleaved LEISA and MVIC acquisitions on an asteroid target. Both MVIC and LEISA obtained data of Dinkinesh and its moon, Selam, demonstrating that they show good spectral agreement with an S- or Sq-type asteroid, along with evidence of a 3 μm absorption feature.

Keywords: Main belt asteroids, Flux calibration
Oxidizing ExoCAM: Introducing the Radiative Effects of Oxygen and Ozone into the ExoCAM General Circulation Model. Oxygen and ozone are two of the most important gases in Earth's atmosphere. These arose as a result of photosynthesis and appeared prominently around 2.3–2.4 billion yr ago. For exoplanets, these species have been proposed both as remote biosignatures and antibiosignatures, depending on the abundances and astrophysical context. ExoCAM, an extension of the Community Earth System Model for deep paleoclimate and exoplanets, has previously been limited to anoxic atmospheres. This work presents a substantial update to the radiative transfer in ExoCAM to include the effects of oxygen and ozone. We describe the implementation of line lists, empirical cross sections, Rayleigh scattering, and collision-induced absorption and test the resulting framework in 1D and 3D for the modern Earth atmosphere. We quantify the changes in flux, temperatures, and circulation due to the two gases.

Keywords: Atmospheric evolution, Earth atmosphere, Atmospheric structure, Planetary atmospheres, Planetary climates, Atmospheric dynamics, Exoplanet atmospheres
Observations and Quantitative Compositional Analysis of Ceres, Pallas, and Hygiea Using JWST/NIRSpec. We present JWST Near Infrared Spectrograph (NIRSpec) measurements of the three largest low-albedo main-belt asteroids: (1) Ceres, (2) Pallas, and (10) Hygiea. Their reflectance spectra all have very similar absorptions centered near 2.72 μm attributed to Mg–OH in minerals. Within this band, Pallas also shows evidence of a sharper, deeper band, also centered near 2.72 μm. These band positions are similar to those seen in the most aqueously altered carbonaceous chondrites and samples from Ryugu and Bennu. Absorptions in the 2.7–2.9 μm region due to other cation–OH combinations are weak, if present. The NIRSpec spectrum of Ceres is consistent with the global average spectrum of Dawn, and the similarity between Ceres and Hygiea seen in other wavelength regions continues into the 2.5–2.8 μm region. This similarity in spectral properties, and thus in interpretations of surface composition, implies that the two bodies may have had similar processes occur and similar histories. This suggests that Hygiea, similar to Ceres, may be associated with the "ocean worlds" despite its relatively small mass. Quantitative estimates of the hydrogen concentrations on the surfaces suggest hydrogen concentrations of roughly 0.5–1 wt%, consistent with CM chondrites. Additional absorptions attributed to ammoniated minerals are seen in Ceres's and Hygiea's spectra, as has been reported by others, but are not seen in Pallas's spectrum. Absorptions are also seen in the 2.5–2.7 μm region in all three asteroids, likely due to OH combination bands, and from roughly 3.9 to 4.3 μm in Hygiea, which could be due to carbonates plus an unidentified constituent.

Keywords: Asteroids, Infrared spectroscopy, Ceres, Main belt asteroids, Pallas
Photolysis and Sublimation Chemistry of Ammonium Cyanide with Relevance to Cometary Environments. Bulk nitrogen is depleted in solar system objects, including the terrestrial planets, chondritic meteorites, and comets. Recently, it was suggested that cometary nitrogen may be locked up in ammonium salts—ionic solids comprising ammonia (NH3) and an acid such as hydrogen cyanide (HCN)—based on Rosetta/ROSINA data from comet 67P/Churyumov–Gerasimanko. Among the proposed salts to have been found in 67P were ammonium cyanide ( ) and ammonium cyanate ( ), which were inferred from identifying HCN, cyanamide ( ), and isocyanic acid (HNCO) in the mass spectrometry data collected in the coma of 67P. However, the relationship between these salts and the proposed tracers had not previously been studied experimentally. We investigated the ultraviolet photolysis and sublimation chemistry of   and   samples formed at 125 K in the laboratory and monitored the ice samples and resulting gas mixtures using infrared and submillimeter spectroscopies, respectively. We find   forms from   but only in the presence of water. When starting from salts, both   and HNCO seem to form only in the gas phase as the salts dissociate upon sublimation and not in the photolyzed ice.

Keywords: Rotational spectroscopy, Ice spectroscopy, Laboratory astrophysics, Molecular spectroscopy, Astrochemistry, Comets
Mapping Venus's Gravity Field with the VERITAS Mission. The Venus Emissivity, Radio Science, InSAR, Topography and Spectroscopy (VERITAS) mission, selected by the NASA Discovery program in 2021, addresses crucial scientific questions about Venus's evolution, structure, and past and ongoing geological processes. The high-resolution mapping of the gravity field of the planet will give an essential contribution to meet the science objectives of the mission and to further our understanding of Venus. The VERITAS gravity science experiment will enable a gravity map of the planet with substantially higher and more uniform spatial resolution with respect to Magellan. This is achieved thanks to the near-polar, near-circular, low-altitude orbit ( 220 km), and the state-of-the-art quality of Doppler tracking data, collected from two separate and coherent radio links at X and Ka band. Our numerical simulations show that the VERITAS gravity science experiment can robustly fulfill the scientific requirements, achieving a gravity field spatial resolution ranging from   to  . Across 90% of the planet, a spatial resolution better than   is expected. Additionally, VERITAS can retrieve crucial parameters required to derive the tidal response and rotational state of Venus, thereby improving our understanding of the planet's interior structure.

Keywords: Gravitational fields, Venus, Solar system terrestrial planets, Planetary science, Orbit determination
Nongravitational Forces in Planetary Systems. Nongravitational forces play surprising and, sometimes, centrally important roles in shaping the motions and properties of small planetary bodies. In the solar system, the morphologies of comets, the delivery of meteorites, and the shapes and dynamics of asteroids and binaries are all affected by nongravitational forces. In exoplanetary systems and debris disks, nongravitational forces affect the lifetimes of circumstellar particles and feed refractory debris to the photospheres of the central stars. Unlike the gravitational force, which is a simple function of the well-known separations and masses of bodies, the nongravitational forces are frequently functions of poorly known or even unmeasurable physical properties. Here, we present order-of-magnitude descriptions of nongravitational forces, with examples of their application.

Keywords: Small Solar System bodies, Asteroids, Main-belt comets, Short period comets, Asteroid satellites, Long period comets, Comets, Debris disks