Showing 1–50 of 116 results for author: Swain, M

What We Observe as LLM Behavior Can Be a Side-effect of Inference Backend

Authors: Shahed Masoudian, Passant Shafaei, Monorama Swain, Markus Schedl

Abstract: Benchmark scores are reported as properties of a model, yet the inference framework used to produce them, such as HuggingFace, vLLM, or Ollama, are considered non-influential and their names and versions are almost never disclosed. In this work we investigate how much this choice can influence the model output. In a fully-crossed study (three instruction-tuned models x five inference frameworks x… ▽ More Benchmark scores are reported as properties of a model, yet the inference framework used to produce them, such as HuggingFace, vLLM, or Ollama, are considered non-influential and their names and versions are almost never disclosed. In this work we investigate how much this choice can influence the model output. In a fully-crossed study (three instruction-tuned models x five inference frameworks x six benchmarks x four generation modes) we investigate how different tools (wrappers/backend) influence benchmark scores and how their score changes is influenced by generation hyper-parameters. We find backend to be a non-negligible factor where even under greedy, sampling-noise-free decoding, changing the backend can significantly alter models performance and this effect is structural and strongly model-dependent. Decomposing the variance according to generation mode reveal that considerable portion of the variability (roughly 39\%) a practitioner sees out-of-the-box can stem from the backend, while the remaining stems from sampling noise and each framework's default generation parameters, both of which are avoidable by disclosing and matching the generation configuration. These divergences are more pronounced on factual than on social-bias benchmarks. Overall, benchmark numbers are not backend-agnostic therefore, we recommend disclosing the backend, its version, and the full generation configuration, also using deterministic decoding for cross-backend comparison. △ Less

Submitted 5 August, 2026; originally announced August 2026.

Phase-curve approach to study atmospheric flows in hot Jupiters

Authors: D. Shulyak, W. Dietrich, V. Parmentier, D. Cont, L. -M. Lara, L. Gkouvelis, M. R. Swain, M. Rengel

Abstract: Short-orbit gaseous exoplanets are the best targets to study atmospheric dynamics. A time series of emission observations collected at various photometric filters (phase curves) provides insights into atmospheric flows. Modern observations reveal a wide variety of phase curves, but their utility for probing atmospheric circulation as a function of altitude has not yet been explored in detail. We a… ▽ More Short-orbit gaseous exoplanets are the best targets to study atmospheric dynamics. A time series of emission observations collected at various photometric filters (phase curves) provides insights into atmospheric flows. Modern observations reveal a wide variety of phase curves, but their utility for probing atmospheric circulation as a function of altitude has not yet been explored in detail. We aim to understand the properties of phase curves and their connection to underlying atmospheric flows, as well as to define a set of multiwavelength observations that could be used to resolve these flows as a function of altitude. We utilized a subset of the solar metallicity models from the grid of ADAM/GCM and state-of-the-art radiative transfer codes to predict phase curves. We made predictions for a variety of photometric filters on board the Spitzer, TESS, CHEOPS, HST, and JWST missions, and explored the sensitivity of each filter to flows at various atmospheric depths. Our calculations show that the main parameter that regulates the phase-curve offsets in our models is the atmospheric temperature, although high metallicity can also have strong impact by reducing phase-curve offsets. This is not fully supported by available observations, which possibly indicates a missing physical process in the models. The predicted contribution functions suggest that the best combination of photometric filters to study atmospheric flows is NIRCam filters because they are sensitive to a wide range of pressures between 10 bar and 1e-4 bar depending on planet temperature, respectively. High-resolution spectroscopy is predicted to detect differential Doppler shifts of 1-4 km/s between molecular bands formed at different altitudes, providing an independent probe of vertical circulations. △ Less

Submitted 4 August, 2026; originally announced August 2026.

Comments: Accepted by A&A

Learning Speaker Identity Beyond Language and Modality Constraints: Insights from the POLY-SIM 2026 Challenge

Authors: Marta Moscati, Muhammad Saad Saeed, Marina Zanoni, Mubashir Noman, Rohan Kumar Das, Monorama Swain, Yassin Terraf, Yufang Hou, Elisabeth Andre, Khalid Mahmood Malik, Markus Schedl, Shah Nawaz

Abstract: Multimodal speaker identification systems typically assume the availability of complete and homogeneous audio-visual modalities during both training and testing, and assume each speaker only speaks a single language. However, in real-world applications, such assumptions often do not hold. Visual or audio information may be missing due to occlusions, camera or microphone failures, or privacy constr… ▽ More Multimodal speaker identification systems typically assume the availability of complete and homogeneous audio-visual modalities during both training and testing, and assume each speaker only speaks a single language. However, in real-world applications, such assumptions often do not hold. Visual or audio information may be missing due to occlusions, camera or microphone failures, or privacy constraints. Multilingual speakers introduce additional complexity due to linguistic variability across languages. These situations constitute substantial challenges for the robustness and generalization capabilities of multimodal speaker identification systems. Aim of the POLY-SIM 2026 challenge is to address these aspects of speaker identification and to provide a standardized setup for the comparison of the proposed solutions. △ Less

Submitted 15 July, 2026; originally announced July 2026.

Comments: Accepted at ACM MM 2026

Preparing for the Early eVolution Explorer: Detecting the Primordial, Transiting Exoplanet Population

Authors: George Zhou, James G. Rogers, Jennifer A. Burt, Eve J. Lee, Sydney Vach, Ann Marie Cody, Mark Swain, Neal J. Turner, Andrew W. Mann, Madyson G. Barber, Eric Gaidos, Ward Howard, Laura Venuti, Damon F. Landau, Valerie Scott, Alan Didion, David Makowski, Jamie Nastal, Evgenya L. Shkolnik, Meredith A. MacGregor

Abstract: The close-in small planet population may be formed either with hydrogen/helium dominated envelopes or with water-rich interiors. Both scenarios reproduce the present day planet population in mass, radius, and periods, and are difficult to differentiate with the mature planet demographic. Hydrogen/Helium `gas-dwarfs' have low mean molecular weight atmospheres, while `water-worlds' have envelopes th… ▽ More The close-in small planet population may be formed either with hydrogen/helium dominated envelopes or with water-rich interiors. Both scenarios reproduce the present day planet population in mass, radius, and periods, and are difficult to differentiate with the mature planet demographic. Hydrogen/Helium `gas-dwarfs' have low mean molecular weight atmospheres, while `water-worlds' have envelopes that are significantly heavier, and as such these two scenarios have different evolution tracks that diverge in the first ~50 Myr of their evolution. We show that a low Earth orbit multi-band photometric survey mission, within the scope of the NASA Small Explorers Program (SMEX), can determine the frequency of young close-in planets at the 5% level and definitively differentiate between the competing `gas-dwarf' and `water-world' hypotheses. We simulate a 2.5 year mission capable of simultaneous multi-band near-ultraviolet (NUV), optical, and near infrared (NIR) wide field photometry. Such a mission would perform a photometric survey of 30 different stare-fields selected to probe the young star population. The mission will yield ~100 transiting planets in young star clusters and associations with ages <50 Myr. In comparison, only 20 such planets are known from K2 and TESS today. △ Less

Submitted 2 June, 2026; originally announced June 2026.

Comments: Accepted for publication in AJ

When Agents Talk: Discourse, Manipulation, and Risk in an Agentic Social Network

Authors: 10a Labs, :, Grace Cheong, Violet Davis, Juliette Garcia, Kendal Gee, Molly Hart, Nicholas Hayes, Henry Houghton, Kyle Lee, Paige Lee, Vicky Lee, Hailey May, Bobby McKenzie, Christine McNeill, Han Nguyen, Brooke Perreault, David Pham, Charlie Plumb, Olivia Quill, Matthew Swain, Grace Wang, Adam Warren, Corie Wieland, Zachary Yahn

Abstract: AI agents are increasingly interacting within shared online environments, creating new operational security risks. We analyze activity on Moltbook, a Reddit-style social platform where AI agents--typically configured and overseen by human operators--post and interact with one another at scale. Using a dataset of 228,684 posts produced by more than 39,500 accounts over a seventeen-day observation w… ▽ More AI agents are increasingly interacting within shared online environments, creating new operational security risks. We analyze activity on Moltbook, a Reddit-style social platform where AI agents--typically configured and overseen by human operators--post and interact with one another at scale. Using a dataset of 228,684 posts produced by more than 39,500 accounts over a seventeen-day observation window, we combine semantic clustering of high-engagement posts with LLM-assisted classification of harmful content and manual review of high-risk samples. The analysis identifies 98 thematic discourse clusters spanning agent infrastructure, autonomy debates, and financial activity. While most observed content was benign, 18.28% of posts contained toxic, manipulative, or malicious material. We cluster malicious content and identify 74 classes of malicious behavior, including credential harvesting attempts, host-execution instructions, proxy routing guidance, and efforts to install untrusted agent skills. Harmful content frequently appeared within mainstream operational discussions about agent functionality. We also document coordinated posting campaigns capable of generating thousands of posts in minutes. △ Less

Submitted 20 May, 2026; originally announced June 2026.

Comparing Results from Two Uniform Phase Curve Surveys

Authors: Emeline Decocq, Mark Swain, Lisa Dang, David R. Ciardi, Geoffrey Bryden

Abstract: We present a comparison of the two most recent and comprehensive Spitzer phase curve studies - Dang et al. (2025) and Swain et al. (2025) - which report analyses of the Spitzer 4.5 $μ$m phase curves. The studies employ different approaches for correcting instrument systematics and they also use different approaches for selecting the optimal exoplanet system parameters. To evaluate the level of con… ▽ More We present a comparison of the two most recent and comprehensive Spitzer phase curve studies - Dang et al. (2025) and Swain et al. (2025) - which report analyses of the Spitzer 4.5 $μ$m phase curves. The studies employ different approaches for correcting instrument systematics and they also use different approaches for selecting the optimal exoplanet system parameters. To evaluate the level of consistency between the two studies, we compared the constraints on the ratio of planet-to-star radii ($R_P/R_\star$), eclipse depth ($F_P/F_\star$), phase curve amplitude ($A$), and phase curve offset ($φ$). We find that the two studies produce similar results at the population level although results for individual planets can vary, especially for phase curve offset values. We examined the difference of planet system parameters to see if inconsistencies in individual planet results were due to data reduction methods or system parameter choices. We also examined whether the system parameters used by both studies were consistent with Kepler's third law. During this comparison, we identified one case where stellar mass, planet semi-major axis, and orbital period did not follow Kepler's law even though the values were all compiled from the same publication. To assess whether this kind of discrepancy was recurrent, we recalculated the orbital periods using Kepler's third law and compared them with the values listed in the NASA Exoplanet Archive. Our detailed analysis of archival system parameters strongly suggests that testing reported/selected parameters for consistency with Kepler's third law is worthwhile. △ Less

Submitted 11 May, 2026; originally announced May 2026.

Comments: 13 pages, 7 figures

Journal ref: The Astronomical Journal, 2026, Volume 171, Number 5

H-RAG at SemEval-2026 Task 8: Hierarchical Parent-Child Retrieval for Multi-Turn RAG Conversations

Authors: Passant Elchafei, Hossam Emam, Mohamed Alansary, Monorama Swain, Markus Schedl

Abstract: We present H-RAG, our submission to SemEval-2026 Task 8 (MTRAGEval), addressing both Task A (Retrieval) and Task C (Generation with Retrieved Passages). Task A evaluates standalone retrieval quality, while Task C assesses end-to-end retrieval-augmented generation (RAG) in multi-turn conversational settings, requiring both accurate answer generation and faithful grounding in retrieved evidence. Our… ▽ More We present H-RAG, our submission to SemEval-2026 Task 8 (MTRAGEval), addressing both Task A (Retrieval) and Task C (Generation with Retrieved Passages). Task A evaluates standalone retrieval quality, while Task C assesses end-to-end retrieval-augmented generation (RAG) in multi-turn conversational settings, requiring both accurate answer generation and faithful grounding in retrieved evidence. Our approach implements a hierarchical parent-child RAG pipeline that separates fine-grained child-level retrieval from parent-level context reconstruction during generation. Documents are segmented into overlapping sentence-based child chunks, while full documents are preserved as parent units to provide coherent context. Retrieval combines hybrid dense-sparse search, tunable weighting, and embedding-based similarity rescoring over child chunks. Retrieved evidence is aggregated at the parent level and supplied to an instruction-tuned language model for response generation. H-RAG achieves an nDCG@5 score of 0.4271 on Task A and a harmonic mean score of 0.3241 on Task C (RB_agg: 0.2488, RL_F: 0.2703, RB_llm: 0.6508), underscoring the importance of retrieval configuration and parent-level aggregation in multi-turn RAG performance. △ Less

Submitted 1 May, 2026; originally announced May 2026.

Facet-Level Tracing of Evidence Uncertainty and Hallucination in RAG

Authors: Passant Elchafei, Monorama Swain, Shahed Masoudian, Markus Schedl

Abstract: Retrieval-Augmented Generation (RAG) aims to reduce hallucination by grounding answers in retrieved evidence, yet hallucinated answers remain common even when relevant documents are available. Existing evaluations focus on answer-level or passage-level accuracy, offering limited insight into how evidence is used during generation. In this work, we introduce a facet-level diagnostics framework for… ▽ More Retrieval-Augmented Generation (RAG) aims to reduce hallucination by grounding answers in retrieved evidence, yet hallucinated answers remain common even when relevant documents are available. Existing evaluations focus on answer-level or passage-level accuracy, offering limited insight into how evidence is used during generation. In this work, we introduce a facet-level diagnostics framework for QA that decomposes each input question into atomic reasoning facets. For each facet, we assess evidence sufficiency and grounding using a structured Facet x Chunk matrix that combines retrieval relevance with natural language inference-based faithfulness scores. To diagnose evidence usage, we analyze three controlled inference modes: Strict RAG, which enforces exclusive reliance on retrieved evidence; Soft RAG, which allows integration of retrieved evidence and parametric knowledge; and LLM-only generation without retrieval. Comparing these modes enables thorough analysis of retrieval-generation misalignment, defined as cases where relevant evidence is retrieved but not correctly integrated during generation. Across medical QA and HotpotQA, we evaluate three open-source and closed-source LLMs (GPT, Gemini, and LLaMA), providing interpretable diagnostics that reveal recurring facet-level failure modes, including evidence absence, evidence misalignment, and prior-driven overrides. Our results demonstrate that hallucinations in RAG systems are driven less by retrieval accuracy and more by how retrieved evidence is integrated during generation, with facet-level analysis exposing systematic evidence override and misalignment patterns that remain hidden under answer-level evaluation. △ Less

Submitted 19 May, 2026; v1 submitted 10 April, 2026; originally announced April 2026.

Gaia DR3 IDs for TESS Input Catalog Targets

Authors: Kevin K. Hardegree-Ullman, Melanie Swain, Jessie L. Christiansen, Emily A. Gilbert, Marcy Harbut, Aurora Y. Kesseli, Michael B. Lund, Meca Lynn, Julian C. van Eyken

Abstract: The TESS Input Catalog (TIC) was built on Gaia Data Release 2 (DR2). To date, there has not been an update to the TIC to incorporate Gaia Data Release 3 (DR3) IDs. In this Research Note, we outline how we cross-matched the TIC with Gaia DR3 IDs, its immediate applications to exoplanet research, and lessons learned when dealing with such large data sets. A full TIC/Gaia DR3 cross-match table is ava… ▽ More The TESS Input Catalog (TIC) was built on Gaia Data Release 2 (DR2). To date, there has not been an update to the TIC to incorporate Gaia Data Release 3 (DR3) IDs. In this Research Note, we outline how we cross-matched the TIC with Gaia DR3 IDs, its immediate applications to exoplanet research, and lessons learned when dealing with such large data sets. A full TIC/Gaia DR3 cross-match table is available for download on the Exoplanet Follow-up Observing Program (ExoFOP) website, and a Jupyter Notebook with instructions to reproduce the table is available on GitHub. △ Less

Submitted 30 March, 2026; originally announced March 2026.

Comments: 4 pages, 1 table. Accepted for publication in RNAAS. Table 1 has been integrated into the NASA Exoplanet Archive and the ExoFOP and is available for full download at https://exofop.ipac.caltech.edu/tess/gaiadr3_tic_crossmatch.php . Code to reproduce Table 1 is available on Github at https://github.com/kevinkhu/ticgaia

POLY-SIM: Polyglot Speaker Identification with Missing Modality Grand Challenge 2026 Evaluation Plan

Authors: Marta Moscati, Muhammad Saad Saeed, Marina Zanoni, Mubashir Noman, Rohan Kumar Das, Monorama Swain, Yufang Hou, Elisabeth Andre, Khalid Mahmood Malik, Markus Schedl, Shah Nawaz

Abstract: Multimodal speaker identification systems typically assume the availability of complete and homogeneous audio-visual modalities during both training and testing. However, in real-world applications, such assumptions often do not hold. Visual information may be missing due to occlusions, camera failures, or privacy constraints, while multilingual speakers introduce additional complexity due to ling… ▽ More Multimodal speaker identification systems typically assume the availability of complete and homogeneous audio-visual modalities during both training and testing. However, in real-world applications, such assumptions often do not hold. Visual information may be missing due to occlusions, camera failures, or privacy constraints, while multilingual speakers introduce additional complexity due to linguistic variability across languages. These challenges significantly affect the robustness and generalization of multimodal speaker identification systems. The POLY-SIM Grand Challenge 2026 aims to advance research in multimodal speaker identification under missing-modality and cross-lingual conditions. Specifically, the Grand Challenge encourages the development of robust methods that can effectively leverage incomplete multimodal inputs while maintaining strong performance across different languages. This report presents the design and organization of the POLY-SIM Grand Challenge 2026, including the dataset, task formulation, evaluation protocol, and baseline model. By providing a standardized benchmark and evaluation framework, the challenge aims to foster progress toward more robust and practical multimodal speaker identification systems. △ Less

Submitted 29 March, 2026; v1 submitted 25 March, 2026; originally announced March 2026.

Comments: Grand challenge at ACM MM 2026

A New Plotly-Dash-based Query Infrastructure for the Keck Observatory Archive

Authors: R. Moseley, G. Bruce Berriman, Christopher R. Gelino, John C. Good, Meca Lynn, Melanie Swain, Toba Oluyide

Abstract: The Keck Observatory Archive (KOA) curates all observational data acquired at the W. M. Keck Observatory. The archive is expected to grow rapidly as complex new instruments are commissioned and as the expectations of archive users have expanded. In response, KOA has implemented a new Python-based, VO-compliant query infrastructure. This work is a continuation of the architectural design and techno… ▽ More The Keck Observatory Archive (KOA) curates all observational data acquired at the W. M. Keck Observatory. The archive is expected to grow rapidly as complex new instruments are commissioned and as the expectations of archive users have expanded. In response, KOA has implemented a new Python-based, VO-compliant query infrastructure. This work is a continuation of the architectural design and technology selection identified at ADASS 2024. We have deployed real-time ingestion of newly acquired data and a dedicated interface for observers to manage these data. Our ADASS 2024 poster identified the new technologies chosen: Plotly-Dash, a low-code framework that exploits event-driven callbacks to simplify the handling of user interactions; R-tree spatial indexing to speed up spatial searches by x20; a VO-compliant TAP middleware, already in use at the NASA Exoplanet Archive and NEID archive; and mViewer, a visualization engine in the Montage Image Mosaic toolkit that is optimized for astronomy images. These technologies will underpin new services that can be hosted on web pages or in Jupyter notebooks, and when completed, will replace the current query infrastructure. We have completed two new services now in beta release. The first is the Data Discovery Service, a web-based dashboard that returns spatial and temporal queries of the entire archive in seconds. It supports filtering observations by keywords, previewing results in an interactive data grid, and visualizing images, and it offers data downloads. The second is a Jupyter notebook that performs interactive visualization of Keck observations of protostars in the Rho Oph Dark Cloud and uses data from CDS and IRSA, as well as KOA. △ Less

Submitted 12 February, 2026; originally announced February 2026.

Comments: 4 pages. Proceedings of Astronomical Society of the Pacific, Goerlitz, 2025

Where does the simplified Stellar Contamination Model fail in Exoplanet Transmission Spectroscopy?

Authors: Viktor Y. D. Sumida, Raissa Estrela, Mark Swain, Adriana Valio

Abstract: Stellar photospheric heterogeneities (e.g., starspots, faculae) distort the stellar spectrum in transit and imprint wavelength-dependent biases on the planet-to-star radius ratio (Transit Light Source Effect, TLSE). The Rackham-TLSE (R-TLSE) prescription applies a disc-averaged correction based solely on filling factor and spectral contrast, but transmission spectroscopy also depends on limb darke… ▽ More Stellar photospheric heterogeneities (e.g., starspots, faculae) distort the stellar spectrum in transit and imprint wavelength-dependent biases on the planet-to-star radius ratio (Transit Light Source Effect, TLSE). The Rackham-TLSE (R-TLSE) prescription applies a disc-averaged correction based solely on filling factor and spectral contrast, but transmission spectroscopy also depends on limb darkening, active-region distribution, and transit geometry. We include these in a pixel-resolved framework, ECLIPSE-Xlambda, and run idealised noise-free model-model comparisons to R-TLSE. For LHS 1140 b, K2-18 b, and WASP-69 b, disc-averaged corrections differ from the pixel model by up to about 400 ppm in the optical for active hosts and non-equatorial transits, but stay below about 10 ppm in the near-infrared where limb darkening is weak. We then apply both approaches to the JWST/NIRISS SOSS spectrum of LHS 1140 b. With limb darkening set to zero, ECLIPSE-Xlambda recovers stellar-contamination parameters matching the reference R-TLSE solution, confirming consistency in the disc-averaged limit. With wavelength-dependent limb darkening, reproducing the short-wavelength slope via stellar contamination alone requires hot faculae (delta Tfac about 600 K; ffac about 0.35), equivalent to a circular facular region of radius about 0.6 Rstar (about 60% of the stellar radius) on the disc; such an extended unocculted region is physically unlikely even for an active M dwarf. Purely stellar contamination would therefore require extreme faculae, whereas a genuine atmospheric contribution complementing a more modest facular signal is more plausible. These results delineate the validity regime of R-TLSE and underscore the need for geometry-aware stellar-heterogeneity models including limb darkening in high-precision transmission spectroscopy. △ Less

Submitted 7 January, 2026; v1 submitted 5 January, 2026; originally announced January 2026.

Journal ref: A&A 706, A281 (2026)

EvalCards: A Framework for Standardized Evaluation Reporting

Authors: Ruchira Dhar, Danae Sanchez Villegas, Antonia Karamolegkou, Alice Schiavone, Yifei Yuan, Xinyi Chen, Jiaang Li, Stella Frank, Laura De Grazia, Monorama Swain, Stephanie Brandl, Daniel Hershcovich, Anders Søgaard, Desmond Elliott

Abstract: Evaluation has long been a central concern in NLP, and transparent reporting practices are more critical than ever in today's landscape of rapidly released open-access models. Drawing on a survey of recent work on evaluation and documentation, we identify three persistent shortcomings in current reporting practices: reproducibility, accessibility, and governance. We argue that existing standardiza… ▽ More Evaluation has long been a central concern in NLP, and transparent reporting practices are more critical than ever in today's landscape of rapidly released open-access models. Drawing on a survey of recent work on evaluation and documentation, we identify three persistent shortcomings in current reporting practices: reproducibility, accessibility, and governance. We argue that existing standardization efforts remain insufficient and introduce Evaluation Disclosure Cards (EvalCards) as a path forward. EvalCards are designed to enhance transparency for both researchers and practitioners while providing a practical foundation to meet emerging governance requirements. △ Less

Submitted 5 November, 2025; originally announced November 2025.

Comments: Under review

Towards Fair ASR For Second Language Speakers Using Fairness Prompted Finetuning

Authors: Monorama Swain, Bubai Maji, Jagabandhu Mishra, Markus Schedl, Anders Søgaard, Jesper Rindom Jensen

Abstract: In this work, we address the challenge of building fair English ASR systems for second-language speakers. Our analysis of widely used ASR models, Whisper and Seamless-M4T, reveals large fluctuations in word error rate (WER) across 26 accent groups, indicating significant fairness gaps. To mitigate this, we propose fairness-prompted finetuning with lightweight adapters, incorporating Spectral Decou… ▽ More In this work, we address the challenge of building fair English ASR systems for second-language speakers. Our analysis of widely used ASR models, Whisper and Seamless-M4T, reveals large fluctuations in word error rate (WER) across 26 accent groups, indicating significant fairness gaps. To mitigate this, we propose fairness-prompted finetuning with lightweight adapters, incorporating Spectral Decoupling (SD), Group Distributionally Robust Optimization (Group-DRO), and Invariant Risk Minimization (IRM). Our proposed fusion of traditional empirical risk minimization (ERM) with cross-entropy and fairness-driven objectives (SD, Group DRO, and IRM) enhances fairness across accent groups while maintaining overall recognition accuracy. In terms of macro-averaged word error rate, our approach achieves a relative improvement of 58.7% and 58.5% over the large pretrained Whisper and SeamlessM4T, and 9.7% and 7.8% over them, finetuning with standard empirical risk minimization with cross-entropy loss. △ Less

Submitted 25 January, 2026; v1 submitted 21 October, 2025; originally announced October 2025.

Comments: Accepted in ICASSP 2026

The Atmospheric Composition of Sub-Neptune K2-18 b and Implications for its Formation

Authors: Gareb Fernández-Rodríguez, Giuseppe Morello, Jonathan C. Tan, Enric Pallé, Mark R. Swain, Efthymios Poultourtzidis, Alfredo Biagini, Quentin Changeat, Chengzi Jiang, Francisco J. Pozuelos, Pedro J. Amado

Abstract: Unlocking the atmospheres of sub-Neptunes is among JWST's major achievements, yet such observations demand complex analyses that strongly affect interpretations. We present an independent reanalysis of the original JWST transmission spectrum of K2-18 b, to assess the robustness of previously claimed detections, explore the parameter space, and implications for its formation. The observations were… ▽ More Unlocking the atmospheres of sub-Neptunes is among JWST's major achievements, yet such observations demand complex analyses that strongly affect interpretations. We present an independent reanalysis of the original JWST transmission spectrum of K2-18 b, to assess the robustness of previously claimed detections, explore the parameter space, and implications for its formation. The observations were reduced using a combination of public and customized pipelines producing a total of 12 different versions of the transmission spectrum by varying: spectral binning, limb-darkening, and a novel correction for the occulted stellar spot. We then performed atmospheric retrievals using TauREx 3, comparing models of varying complexity, robustly detecting CH$_4$ (3-4$σ$) across all configurations. The evidence for CO$_2$ is weaker and highly model-dependent. The tentative detection of dimethyl sulphide (DMS) vanishes in our most comprehensive retrieval models. We find that correcting the stellar spot in the NIRISS transit is a critical step, introducing a uniform offset that primarily drives the inference of a lower mean molecular weight atmosphere. Furthermore, the assumed complexity of the retrieval model itself introduces significant biases; including more molecules systematically increases the retrieved CH$_4$ abundance and atmospheric mean molecular weight, even for species without spectral features. The data are consistent with a hydrogen-rich atmosphere with an elevated O and an even more elevated C abundance, leading to a super-solar C/O. We show that the physical properties of the system planets K2-18 c, and K2-18 b are consistent with those expected by the in situ formation theory of Inside-Out Planet Formation (IOPF), interior to the carbon "soot" line, where an elevated C/O ratio of a primordial atmosphere is expected to be inherited from the protoplanetary disk. △ Less

Submitted 20 October, 2025; originally announced October 2025.

Comments: Comments welcome

TESS Discovers a Second System of Transiting Exocomets in the Extreme Debris Disk of RZ Psc

Authors: Adalyn Gibson, Meredith A. MacGregor, Ward S. Howard, Ann Marie Cody, Mark Swain, Jennifer A. Burt, Laura Venuti, Evgenya Shkolnik, Neal J. Turner, Alan Didion, Jaime Nastal, David Makowski

Abstract: We present the TESS discovery of only the second system of transiting exocomets with a sufficient number of events to measure the size distribution in the RZ Psc system, enabling comparisons with the $β$ Pictoris and Solar System size distributions. Twenty-four transits with absorption depths (AD) of 1--20\% were observed across three TESS sectors of the 20-50 Myr K0V star, detected as part of our… ▽ More We present the TESS discovery of only the second system of transiting exocomets with a sufficient number of events to measure the size distribution in the RZ Psc system, enabling comparisons with the $β$ Pictoris and Solar System size distributions. Twenty-four transits with absorption depths (AD) of 1--20\% were observed across three TESS sectors of the 20-50 Myr K0V star, detected as part of our TESS survey of extreme debris disks identified by their IR excess. We discover that the ADs (and hence exocomet radii) follow a broken power-law cumulative frequency distribution not previously seen in extrasolar contexts but similar to that observed in Solar System Kuiper Belt Object sizes, with power-law slopes above and below the break of $γ_\mathrm{AD>break}$=2.32$\pm$0.12 and $γ_\mathrm{AD<break}$=0.11$\pm$0.04, respectively. We derive size distributions of 1--7~km from two independent lines of evidence. We use the RZ Psc exocomet rate to predict exocomet yields for the Early eVolution Explorer (EVE) NASA astrophysics Small Explorer (SMEX) mission concept to obtain simultaneous photometry of 10$^4$ young stars in NUV, optical, and NIR bands. Assuming occurrence rates scaled from RZ Psc, EVE would detect 590 exocomets from $\approx$70 young systems in the optical band, with $\approx$120 simultaneous 5$σ$ detections in all three bands. These data would enable grain sizes of 200--700~nm and graphite--olivine compositions of dozens of events to be distinguished at 2.5--3$σ$, as well as a 4$σ$ determination of the accuracy of the Herschel-derived M-debris disk fraction. △ Less

Submitted 10 October, 2025; originally announced October 2025.

Comments: 16 pages, 8 figures, accepted to ApJ Letters

A New Approach to Compiling Exoatmospheric Target Lists And Quantifying the Ground-Based Resources Needed to Vet Them

Authors: Jennifer A. Burt, Robert T. Zellem, David R. Ciardi, Shubham Kanodia, Geoffrey Bryden, Tiffany Kataria, Kyle A. Pearson, Jessie L. Christiansen, Charles Beichman, B. J. Fulton, Mark Swain

Abstract: Transiting exoplanet atmospheric characterization is currently in a golden age as dozens of exoplanet atmospheres are being studied by NASA's Hubble and James Webb Space Telescopes. This trend is expected to continue with NASA's Pandora Smallsat and Roman Space Telescope and ESA's Ariel mission (all expected to launch within this decade) and NASA's Habitable Worlds Observatory (expected to launch… ▽ More Transiting exoplanet atmospheric characterization is currently in a golden age as dozens of exoplanet atmospheres are being studied by NASA's Hubble and James Webb Space Telescopes. This trend is expected to continue with NASA's Pandora Smallsat and Roman Space Telescope and ESA's Ariel mission (all expected to launch within this decade) and NASA's Habitable Worlds Observatory (expected to launch in the early 2040s) all of which are centered around studying the atmospheres of exoplanets. Here we explore a new approach to constructing large scale exoatmospheric survey lists, which combines the use of traditional transmission/emission spectroscopy figures of merit with a focus on more-evenly sampling planets across a range of radii and equilibrium temperatures. After assembling a sample target list comprised of 750 transmission spectroscopy targets and 150 emission spectroscopy targets, we quantify the potential time lost to stale transit and eclipse ephemerides and find that hundreds of hours of space-based observing could be wasted given current uncertainties in orbital periods, transit epochs, and orbital eccentricities. We further estimate the amount of ground-based telescope time necessary to obtain sufficiently precise exoplanet masses and find that it exceeds 100 nights of 10m telescope time. Based upon these findings, we provide a list of recommendations that would make community efforts for preparation and interpretation of atmospheric characterization endeavors more effective and efficient. The strategies we recommend here can be used to support both current (e.g., HST and JWST) and future exoplanet atmosphere characterization missions (e.g., Pandora, Ariel, Roman, and the Habitable Worlds Observatory). △ Less

Submitted 3 September, 2025; v1 submitted 5 August, 2025; originally announced August 2025.

Comments: 25 pages, 13 figures, 2 tables. Accepted for publication in the Astronomical Journal

Building SPARCS, an Ultraviolet Science CubeSat for Exoplanet Habitability Studies, Technology Advancements, and Mission Training

Authors: Evgenya L. Shkolnik, David R. Ardila, Logan Jensen, April D. Jewell, Tahina Ramiaramanantsoa, Judd Bowman, Daniel Jacobs, Paul Scowen, Christophe Basset, Johnathan Gamaunt, Dawn Gregory, Maria C. Ladwig, Matthew Kolopanis, Shouleh Nikzad, Nathaniel Struebel, Joe Llama, Mary Knapp, Sarah Peacock, Titu Samson, Mark Swain

Abstract: The Star-Planet Activity Research CubeSat (SPARCS) is a NASA-funded 6U-CubeSat mission designed to monitor ultraviolet (UV) radiation from low-mass stars. These stars' relatively high-frequency and high-energy UV flares significantly affect the atmospheres of orbiting exoplanets, driving atmospheric loss and altering the conditions for habitability. SPARCS aims to capture time-resolved photometric… ▽ More The Star-Planet Activity Research CubeSat (SPARCS) is a NASA-funded 6U-CubeSat mission designed to monitor ultraviolet (UV) radiation from low-mass stars. These stars' relatively high-frequency and high-energy UV flares significantly affect the atmospheres of orbiting exoplanets, driving atmospheric loss and altering the conditions for habitability. SPARCS aims to capture time-resolved photometric data in the far-UV and near-UV simultaneously to better characterize the flares and detect the strongest and rarest among them. In addition, SPARCS is testing innovative technology, such as delta-doped detectors with near 100% internal quantum efficiency and detector-integrated metaldielectric UV bandpass filters. This mission will increase the technology readiness level of these critical components, positioning them for inclusion in future flagship missions like the Habitable Worlds Observatory. This paper outlines SPARCS' mission goals and provides an update as the spacecraft is completed and awaits its planned late-2025 launch to a sun-synchronous low-Earth orbit. It also highlights the critical role of small missions in providing training and leadership development opportunities for students and researchers, advancing technology for larger observatories, and shares lessons learned from collaborations between academic, government, and industry partners. △ Less

Submitted 3 July, 2025; originally announced July 2025.

Comments: Accepted for publication in Journal of Astronomical Telescopes, Instruments, and Systems (JATIS)

The NASA Exoplanet Archive and Exoplanet Follow-up Observing Program: Data, Tools, and Usage

Authors: Jessie L. Christiansen, Douglas L. McElroy, Marcy Harbut, David R. Ciardi, Megan Crane, John Good, Kevin K. Hardegree-Ullman, Aurora Y. Kesseli, Michael B. Lund, Meca Lynn, Ananda Muthiar, Ricky Nilsson, Toba Oluyide, Michael Papin, Amalia Rivera, Melanie Swain, Nicholas D. Susemiehl, Raymond Tam, Julian van Eyken, Charles Beichman

Abstract: The NASA Exoplanet Archive and the Exoplanet Follow-up Observing Program service are two widely used resources for the exoplanet community. The NASA Exoplanet Archive provides a complete and accurate accounting of exoplanetary systems published by NASA missions and by the community in the refereed literature. In anticipation of continued exponential growth in the number of exoplanetary systems, an… ▽ More The NASA Exoplanet Archive and the Exoplanet Follow-up Observing Program service are two widely used resources for the exoplanet community. The NASA Exoplanet Archive provides a complete and accurate accounting of exoplanetary systems published by NASA missions and by the community in the refereed literature. In anticipation of continued exponential growth in the number of exoplanetary systems, and the increasing complexity in our characterization of these systems, the NASA Exoplanet Archive has restructured its primary tables and interfaces, as well as extending and standardizing their modes of access. The Exoplanet Follow-up Observing Program service provides the exoplanet community with a venue for coordinating and sharing follow-up and precursor data for exoplanets, their host stars, and stars that might eventually be targets for future planet searches, and recently reached one million files uploaded by the community. In this paper we describe the updates to our data holdings, functionality, accessibility, and tools, as well as future priorities for these two services. △ Less

Submitted 3 June, 2025; originally announced June 2025.

Comments: 18 pages, 7 figures, 4 tables. Replaces Akeson et al. (2013) as the citation for the NASA Exoplanet Archive and Exoplanet Follow-up Observing Program (ExoFOP), accepted in PSJ

Thermal Phase Curves in Hot Gas Giant Exoplanets Exhibit a Complex Dependence on Planetary Properties

Authors: Mark R Swain, Kyle A Pearson, Thaddeus D. Komacek, Geoffrey Bryden, Emeline Fromont, Gautam Vasisht, Gael Roudier, Robert T. Zellem

Abstract: We present a catalog of uniformly processed 3.6-$μ$m and 4.5-$μ$m band exoplanet thermal phase curves based on Infrared Array Camera observations obtained from the Spitzer Heritage Archive. The catalog includes phase curve measurements for 34 planets, 16 of which contain full orbit coverage and have detectable secondary eclipses in both channels. The data are processed in the EXCALIBUR pipeline us… ▽ More We present a catalog of uniformly processed 3.6-$μ$m and 4.5-$μ$m band exoplanet thermal phase curves based on Infrared Array Camera observations obtained from the Spitzer Heritage Archive. The catalog includes phase curve measurements for 34 planets, 16 of which contain full orbit coverage and have detectable secondary eclipses in both channels. The data are processed in the EXCALIBUR pipeline using a uniform analysis consisting of aperture photometry and modeling of instrument effects along with the exoplanet signal. Nearest-neighbors regression with a Gaussian kernel is used to correct for instrumental systematics correlated to the star's centroid position and shape in conjunction with a novel test to avoid overfitting. These methods may have utility in addressing sub-pixel gain variations present in modern infrared detectors. We analyze the 3.6-$μ$m and 4.5-$μ$m phase curve properties and find a strong wavelength-dependent difference in how the properties correlate with physical parameters as well as evidence that the phase curve properties are determined by multiple physical parameters. We suggest that differences between the 3.6-$μ$m and 4.5-$μ$m phase curve properties are due to 3.6~$μ$m observations probing regions of the atmosphere which could include a cloud layer. Taken together, the observed phase curve behavior suggests that different physical processes are responsible for establishing the thermal phase curve at different pressures, which are probed by different wavelengths, and that further 3D GCM modeling is required to investigate the reason for this complex dependence on planetary properties. △ Less

Submitted 28 February, 2025; originally announced March 2025.

Comments: 20 pages, 7 figures, accepted for publication ApJ

Exploring the atmosphere of GJ 1132 b with CRIRES+

Authors: E. Palle, F. Yan, G. Morello, M. Stangret, M. R. Swain, J. Orell-Miquel, P. Miles-Paez, R. Estrela, T. Masseron, G. Roudier, P. B. Rimmer

Abstract: With a mass, radius, and mean density similar to Earth's, the rocky planet GJ 1132 b is the first truly small planet for which an atmosphere detection was proposed. If confirmed, ultra-reduced magma outgassing is the only mechanism capable of producing HCN and H$_2$O in large enough quantities to match the HST observations. The proposed atmosphere detection, however was challenged by reanalysis of… ▽ More With a mass, radius, and mean density similar to Earth's, the rocky planet GJ 1132 b is the first truly small planet for which an atmosphere detection was proposed. If confirmed, ultra-reduced magma outgassing is the only mechanism capable of producing HCN and H$_2$O in large enough quantities to match the HST observations. The proposed atmosphere detection, however was challenged by reanalysis of the same HST data by different teams. Recent JWST observations returned ambiguous results due to the unaccounted for variability seen between two different visits. Here we report the analysis of three CRIRES+ transit observations of GJ 1132 b in order to determine the presence or absence of He I, HCN, CH$_4$, and H$_2$O in its atmosphere. We are unable to detect the presence of any of these species in the atmosphere of GJ 1132 b assuming a clear, H$_2$-dominated atmosphere, although we can place upper limits for the volume mixing ratios of CH$_4$, HCN, and H$_2$O using injections tests and atmospheric retrievals. These retrieved upper limits show the capability of CRIRES+ to detecting chemical species in rocky exoplanets, if the atmosphere is H$_2$ dominated. The detection of the atmospheres of small planets with high mean molecular weight, and the capability to distinguish between the variability introduced by stellar activity and/or the planetary atmosphere will require high-resolution spectrographs in the upcoming extremely large telescopes. △ Less

Submitted 27 February, 2025; originally announced February 2025.

Comments: Accepted for publication in A&A

Journal ref: A&A 697, A31 (2025)

Planet Mass and Metallicity: The Exoplanets and Solar System Connection

Authors: Mark R. Swain, Yasuhiro Hasegawa, Daniel P. Thorngren, Gael M. Roudier

Abstract: Theoretical studies of giant planet formation suggest that substantial quantities of metals - elements heavier than hydrogen and helium - can be delivered by solid accretion during the envelope-assembly phase. This metal enhancement process is believed to diminish as a function of planet mass, leading to predictions for a mass-metallicity relationship. This picture is supported by the abundance of… ▽ More Theoretical studies of giant planet formation suggest that substantial quantities of metals - elements heavier than hydrogen and helium - can be delivered by solid accretion during the envelope-assembly phase. This metal enhancement process is believed to diminish as a function of planet mass, leading to predictions for a mass-metallicity relationship. This picture is supported by the abundance of CH$_4$ in solar system giant planets, which is unaffected by condensation, unlike H$_2$O. However, all of the solar system giants exhibit some evidence for stratification of metals outside of their cores. In this context, two fundamental questions are whether metallicity of giant planets inferred from observations of the outer envelope layers represents their bulk metallicities, and if not, how are metals distributed within these planets. Comparing the mass-metallicity relationship inferred for solar system giants with various tracers of exoplanet metallicity has yielded a range of results. There is evidence of a solar-system-like mass-metallicity trend using bulk density estimates of exoplanets. However, transit-spectroscopy-based tracers of exoplanet metallicity, which probe only the outer layers of the envelope, are less clear about a mass-metallicity trend and radial composition gradients. The large number of known exoplanets enables statistical characterization. We develop a formalism for comparing both the metallicity inferred for the outer envelope and the metallicity inferred using the bulk density and show this combination may offer insights into metal stratification within planetary envelopes. Thus, future exoplanet observations with JWST and Ariel will be able to shed light on the conditions governing radial composition gradients in exoplanets and, perhaps, provide information about the factors controlling stratification and convection in our solar system gas giants. △ Less

Submitted 20 September, 2024; originally announced September 2024.

Comments: 32 pages, 10 figures; published in Space Science Reviews

Bulk and atmospheric metallicities as direct probes of sequentially varying accretion mechanisms of gas and solids onto planets

Authors: Yasuhiro Hasegawa, Mark R. Swain

Abstract: Core accretion is the standard scenario of planet formation, wherein planets are formed by sequential accretion of gas and solids, and is widely used to interpret exoplanet observations. However, no direct probes of the scenario have been discussed yet. Here, we introduce an onion-like model as one idealization of sequential accretion and propose that bulk and atmospheric metallicities of exoplane… ▽ More Core accretion is the standard scenario of planet formation, wherein planets are formed by sequential accretion of gas and solids, and is widely used to interpret exoplanet observations. However, no direct probes of the scenario have been discussed yet. Here, we introduce an onion-like model as one idealization of sequential accretion and propose that bulk and atmospheric metallicities of exoplanets can be used as direct probes of the process. Our analytical calculations, coupled with observational data, demonstrate that the trend of observed exoplanets supports the sequential accretion hypothesis. In particular, accretion of planetesimals that are $\gtrsim $ 100 km in size is most favored to consistently explain the observed trends. The importance of opening gaps in both planetesimal and gas disks following planetary growth is also identified. New classification is proposed, wherein most observed planets are classified into two interior statuses: globally mixed and locally (well-)mixed. Explicit identification of the locally (well-)mixed status enables reliable verification of sequential accretion. During the JWST era, the quality and volume of observational data will increase drastically and improve exoplanet characterization. This work provides one key reference of how both the bulk and atmospheric metallicities can be used to constrain gas and solid accretion mechanisms of planets. △ Less

Submitted 10 September, 2024; originally announced September 2024.

Comments: 14pages, 4 figures, 1 table; accepted for publication in ApJ Letters

A Comprehensive Analysis Spitzer 4.5 $μ$m Phase Curve of Hot Jupiters

Authors: Lisa Dang, Taylor J. Bell, Ying, Shu, Nicolas B. Cowan, Jacob L. Bean, Drake Deming, Eliza M. -R. Kempton, Megan Weiner Mansfield, Emily Rauscher, Vivien Parmentier, Kevin B. Stevenson, Mark Swain, Laura Kreidberg, Tiffany Kataria, Jean-Michel Désert, Robert Zellem, Jonathan J. Fortney, Nikole K. Lewis, Michael Line, Caroline Morley, Adam Showman

Abstract: Although exoplanetary science was not initially projected to be a substantial part of the Spitzer mission, its exoplanet observations set the stage for current and future surveys with JWST and Ariel. We present a comprehensive reduction and analysis of Spitzer's 4.5 micron phase curves of 29 hot Jupiters on low-eccentricity orbits. The analysis, performed with the Spitzer Phase Curve Analysis (SPC… ▽ More Although exoplanetary science was not initially projected to be a substantial part of the Spitzer mission, its exoplanet observations set the stage for current and future surveys with JWST and Ariel. We present a comprehensive reduction and analysis of Spitzer's 4.5 micron phase curves of 29 hot Jupiters on low-eccentricity orbits. The analysis, performed with the Spitzer Phase Curve Analysis (SPCA) pipeline, confirms that BLISS mapping is the best detrending scheme for most, but not all, observations. Visual inspection remains necessary to ensure consistency across detrending methods due to the diversity of phase curve data and systematics. Regardless of the model selection scheme - whether using the lowest-BIC or a uniform detrending approach - we observe the same trends, or lack thereof. We explore phase curve trends as a function of irradiation temperature, orbital period, planetary radius, mass, and stellar effective temperature. We discuss the trends that are robustly detected and provide potential explanations for those that are not observed. While it is almost tautological that planets receiving greater instellation are hotter, we are still far from confirming dynamical theories of heat transport in hot Jupiter atmospheres due to the sample's diversity. Even among planets with similar temperatures, other factors like rotation and metallicity vary significantly. Larger, curated sample sizes and higher-fidelity phase curve measurements from JWST and Ariel are needed to firmly establish the parameters governing day-night heat transport on synchronously rotating planets. △ Less

Submitted 23 August, 2024; originally announced August 2024.

Comments: 16 pages, 6 figures, submitted to AAS journal

Integration of Data Reduction and Near Real-Time Archiving into the Keck Observing Model

Authors: Max Brodheim, John O'Meara, Jeffrey A. Mader, G. Bruce Berriman, Matthew Brown, Lucas Furhman, Tyler Tucker, Christopher R. Gelino, Meca S. Lynn, Melanie A. Swain

Abstract: The W. M. Keck Observatory is welcoming a new era where data reduction and archiving are tightly integrated into our observing model, under the auspices of the Observatory's Data Services Initiative (DSI) project. While previously the Keck Observatory Archive (KOA) archived minimally processed, raw science data the day after observing, Keck is transitioning to a model in which it archives both raw… ▽ More The W. M. Keck Observatory is welcoming a new era where data reduction and archiving are tightly integrated into our observing model, under the auspices of the Observatory's Data Services Initiative (DSI) project. While previously the Keck Observatory Archive (KOA) archived minimally processed, raw science data the day after observing, Keck is transitioning to a model in which it archives both raw frames and reduced data in near real-time. These data will be made available to observers and collaborators immediately upon ingestion through a dedicated new interface that will support collaboration and sharing among teams, as well as stream data directly to personal computers without access to WMKO's internal networks. Both the raw and science-ready data products will be made publicly available upon the expiration of data protections. △ Less

Submitted 6 June, 2024; originally announced June 2024.

Comments: 10 pages, 5 figures, SPIE Astronomical Telescopes + Instrumentation 2022

Journal ref: Proc. SPIE 12186, Observatory Operations: Strategies, Processes, and Systems IX, 121860H (25 August 2022)

Comparing transit spectroscopy pipelines at the catalogue level: evidence for systematic differences

Authors: Lorenzo V. Mugnai, Mark R. Swain, Raissa Estrela, Gael M. Roudier

Abstract: The challenge of inconsistent results from different data pipelines, even when starting from identical data, is a recognized concern in exoplanetary science. As we transition into the James Webb Space Telescope (JWST) era and prepare for the ARIEL space mission, addressing this issue becomes paramount because of its implications on our understanding of exoplanets. Although comparing pipeline resul… ▽ More The challenge of inconsistent results from different data pipelines, even when starting from identical data, is a recognized concern in exoplanetary science. As we transition into the James Webb Space Telescope (JWST) era and prepare for the ARIEL space mission, addressing this issue becomes paramount because of its implications on our understanding of exoplanets. Although comparing pipeline results for individual exoplanets has become more common, this study is the first to compare pipeline results at the catalogue level. We present a comprehensive framework to statistically compare the outcomes of data analysis reduction on a population of exoplanets and we leverage the large number of observations conducted using the same instrument configured with HST-WFC3. We employ three independent pipelines: Iraclis, EXCALIBUR, and CASCADe. Our combined findings reveal that these pipelines, despite starting from the same data and planet system parameters, yield substantially different spectra in some cases. However, the most significant manifestations of pipeline differences are observed in the compositional trends of the resulting exoplanet catalogues. We conclude that pipeline-induced differences lead to biases in the retrieved information, which are not reflected in the retrieved uncertainties. Our findings underscore the critical need to confront these pipeline differences to ensure the reproducibility, accuracy, and reliability of results in exoplanetary research. Our results demonstrate the need to understand the potential for population-level bias that pipelines may inject, which could compromise our understanding of exoplanets as a class of objects. △ Less

Submitted 9 April, 2024; v1 submitted 24 February, 2024; originally announced February 2024.

Comments: 17 pages, 11 figures, submitted to MNRAS, changes in Table 2

Journal ref: MNRAS, Volume 531, Issue 1, June 2024, Pages 35-51

The Observers' Data Access Portal at the Keck Observatory Archive

Authors: T. Oluyide, M. S. Lynn, T. Coda, G. B. Berriman, M. Brown, L. Fuhrman, C. Gelino, J. Good, J. Hayashi, C. -H. Lee, J. Mader, M. A. Swain

Abstract: For all active instruments, the Keck Observatory Archive (KOA) now ingests raw data from the Keck Telescopes within 1 minute of acquisition, quick-look reduced data within 5 minutes of creation, and science ready reduced data for four instruments as they are created by their automated pipelines. On August 1, 2023, KOA released the Observers Data Access Portal (ODAP), which enables observers at the… ▽ More For all active instruments, the Keck Observatory Archive (KOA) now ingests raw data from the Keck Telescopes within 1 minute of acquisition, quick-look reduced data within 5 minutes of creation, and science ready reduced data for four instruments as they are created by their automated pipelines. On August 1, 2023, KOA released the Observers Data Access Portal (ODAP), which enables observers at the telescope and their collaborators anywhere in the world to securely monitor and download science, calibration, and quick-look data as they are ingested into the archive. The portal is built using Python Socket IO.WebSockets that ensure metadata appear in the portal as the data themselves are ingested. The portal itself is a dynamic web interface built with React. It enables users to view and customize metadata fields, filter metadata according to data type, and download data as they are ingested or in bulk through wget scripts. Observers have used the ODAP since its release and have provided feedback that will guide future releases. △ Less

Submitted 6 February, 2024; originally announced February 2024.

Comments: 4 pages, 2 figs, ADASS 2024 proceedings

Experimental Investigation of the Photochemical Production of Hydrocarbons in Warm Gas Giant Exoplanet Atmospheres

Authors: Benjamin Fleury, Yves Benilan, Olivia Venot, Bryana L. Henderson, Mark Swain, Murthy S. Gudipati

Abstract: In warm (equilibrium temperature <1000 K) gas giant exoplanet atmospheres, the observation of trace species in abundances deviating from thermochemical equilibrium predictions could be used as an indicator of disequilibrium chemical processes, such as photochemistry. To predict which compounds could be used as such tracers, it is therefore essential to study how photochemical processes affect thei… ▽ More In warm (equilibrium temperature <1000 K) gas giant exoplanet atmospheres, the observation of trace species in abundances deviating from thermochemical equilibrium predictions could be used as an indicator of disequilibrium chemical processes, such as photochemistry. To predict which compounds could be used as such tracers, it is therefore essential to study how photochemical processes affect their abundances. For this purpose, we investigated experimentally the efficiency of the photochemical formation of hydrocarbons in gas mixtures representative of warm gas giant atmospheres as a function of the gas temperature at millibar pressures. We find that, compared to thermal reactions alone, photochemistry efficiently promotes, under the studied conditions, the formation of hydrocarbons, with the detection of acetylene, ethane, and propane, as well as carbon monoxide. Therefore, our results confirm the importance of photochemistry in exoplanet atmospheres as a disequilibrium process. Ethane is the major hydrocarbon formed in our experiments, in apparent contradiction with the prediction by thermophotochemical models that acetylene should be the main hydrocarbon product. We also observe an evolution of the hydrocarbon production efficiency as a function of the temperature, a behavior not reproduced by a 0D thermophotochemical model. Additional studies are necessary to definitively understand the origin of the differences between the experimental and modeling results and to infer the importance of our results for understanding hydrocarbon formation in warm gas giant exoplanet atmospheres. Finally, our work demonstrates the importance of experimental studies together with modeling studies to accurately interpret, understand, and predict observations of exoplanet atmospheres. △ Less

Submitted 17 October, 2023; originally announced October 2023.

Comments: 37 pages, 4 tables, 13 figures

Journal ref: The Astrophysical Journal, 956:134 (15pp), 2023 October 20

Real-time Data Ingestion at the Keck Observatory Archive (KOA)

Authors: G. Bruce Berriman, M. Brodheim, M. Brown, L. Fuhrman, C. R. Gelino, M. Kong, C. -H. Lee, M. S. Lynn, J. Mader, T. Oluyide, M. A. Swain, T. Tucker, A. Laity, J. Riley

Abstract: Since February of this year, KOA began to prepare, transfer, and ingest data as they were acquired in near-real time; in most cases data are available to observers through KOA within one minute of acquisition. Real-time ingestion will be complete for all active instruments by the end of Summer 2022. The observatory is supporting the development of modern Python data reduction pipelines, which when… ▽ More Since February of this year, KOA began to prepare, transfer, and ingest data as they were acquired in near-real time; in most cases data are available to observers through KOA within one minute of acquisition. Real-time ingestion will be complete for all active instruments by the end of Summer 2022. The observatory is supporting the development of modern Python data reduction pipelines, which when delivered, will automatically create science-ready data sets at the end of each night for ingestion into the archive. This presentation will describe the infrastructure developed to support real-time data ingestion, itself part of a larger initiative at the Observatory to modernize end-to-end operations. During telescope operations, the software at WMKO is executed automatically when a newly acquired file is recognized through monitoring a keyword-based observatory control system; this system is used at Keck to execute virtually all observatory functions. The monitor uses callbacks built into the control system to begin data preparation of files for transmission to the archive on an individual basis: scheduling scripts or file system related triggers are unnecessary. An HTTP-based system called from the Flask micro-framework enables file transfers between WMKO and NExScI and triggers data ingestion at NExScI. The ingestion system at NEXScI is a compact (4 KLOC), highly fault-tolerant, Python-based system. It uses a shared file system to transfer data from WMKO to NExScI. The ingestion code is instrument agnostic, with instrument parameters read from configuration files. It replaces an unwieldy (50 KLOC) C-based system that had been in use since 2004. △ Less

Submitted 5 December, 2022; originally announced December 2022.

Comments: 4 pages, 3 figures

The Star-Planet Activity Research CubeSat (SPARCS): Determining Inputs to Planetary Habitability

Authors: David R. Ardila, Evgenya Shkolnik, Paul Scowen, Daniel Jacobs, Dawn Gregory, Travis Barman, Christopher Basset, Judd Bowman, Samuel Cheng, Jonathan Gamaut, Logan Jensen, April Jewell, Mary Knapp, Matthew Kolopanis, Joseph Llama, R. O. Parke Loyd, Victoria Meadows, Shouleh Nikzad, Sara Peacock, Tahina Ramiaramanantsoa, Nathaniel Struebel, Mark Swain

Abstract: Seventy-five billion low-mass stars in our galaxy host at least one small planet in their habitable zone (HZ). The stellar ultraviolet (UV) radiation received by the planets is strong and highly variable, and has consequences for atmospheric loss, composition, and habitability. SPARCS is a NASA-funded mission to characterize the quiescent and flare UV emission from low-mass stars, by observing 1… ▽ More Seventy-five billion low-mass stars in our galaxy host at least one small planet in their habitable zone (HZ). The stellar ultraviolet (UV) radiation received by the planets is strong and highly variable, and has consequences for atmospheric loss, composition, and habitability. SPARCS is a NASA-funded mission to characterize the quiescent and flare UV emission from low-mass stars, by observing 10 to 20 low-mass stars, over timescales of days, simultaneously in two UV bands: 153-171 nm and 260-300 nm. SPARCS Sun-synchronous terminator orbit allows for long periods of uninterrupted observations, reaching 10s of days for some targets. The payload consists of a 10 cm-class telescope, a dichroic element, UV detectors and associated electronics, a thermal control system, and an on-board processor. The payload is hosted on a Blue Canyon Technologies 6U CubeSat. SPARCS hosts several technology innovations that have broad applicability to other missions. The payload demonstrates the use of "2D-doped" (i.e., delta- and superlattice-doped) detectors and detector-integrated metal dielectric filters in space. This detector technology provides ~5x larger quantum efficiency than NASA's GALEX detectors. In addition, SPARCS' payload processor provides dynamic exposure control, automatically adjusting the exposure time to avoid flare saturation and to time-resolve the strongest stellar flares. A simple passive cooling system maintains the detector temperature under 238K to minimize dark current. The spacecraft bus provides pointing jitter smaller than 6", minimizing the impact of flat-field errors, dark current, and read-noise. All these elements enable competitive astrophysics science within a CubeSat platform. SPARCS is currently in the final design and fabrication phase (Phase C in the NASA context). It will be launched in 2024, for a primary science mission of one year. △ Less

Submitted 10 November, 2022; originally announced November 2022.

Comments: Presented at the 73rd International Astronautical Congress, 18-22 September 2022, Paris, France

The UV-SCOPE Mission: Ultraviolet Spectroscopic Characterization Of Planets and their Environments

Authors: David R. Ardila, Evgenya Shkolnik, John Ziemer, Mark Swain, James E. Owen, Michael Line, R. O. Parke Loyd, R. Glenn Sellar, Travis Barman, Courtney Dressing, William Frazier, April D. Jewell, Robert J. Kinsey, Carl C. Liebe, Joshua D. Lothringer, Luz Maria Martinez-Sierra, James McGuire, Victoria Meadows, Ruth Murray-Clay, Shouleh Nikzad, Sarah Peacock, Hilke Schlichting, David Sing, Kevin Stevenson, Yen-Hung Wu

Abstract: UV-SCOPE is a mission concept to determine the causes of atmospheric mass loss in exoplanets, investigate the mechanisms driving aerosol formation in hot Jupiters, and study the influence of the stellar environment on atmospheric evolution and habitability. As part of these investigations, the mission will generate a broad-purpose legacy database of time-domain ultraviolet (UV) spectra for nearly… ▽ More UV-SCOPE is a mission concept to determine the causes of atmospheric mass loss in exoplanets, investigate the mechanisms driving aerosol formation in hot Jupiters, and study the influence of the stellar environment on atmospheric evolution and habitability. As part of these investigations, the mission will generate a broad-purpose legacy database of time-domain ultraviolet (UV) spectra for nearly 200 stars and planets. The observatory consists of a 60 cm, f/10 telescope paired to a long-slit spectrograph, yielding simultaneous, almost continuous coverage between 1203 Å and 4000 Å, with resolutions ranging from 6000 to 240. The efficient instrument provides throughputs > 4% (far-UV; FUV) and > 15% (near-UV; NUV), comparable to HST/COS and much better than HST/STIS, over the same spectral range. A key design feature is the LiF prism, which serves as a dispersive element and provides high throughput even after accounting for radiation degradation. The use of two delta-doped Electron-Multiplying CCD detectors with UV-optimized, single-layer anti-reflection coatings provides high quantum efficiency and low detector noise. From the Earth-Sun second Lagrangian point, UV-SCOPE will continuously observe planetary transits and stellar variability in the full FUV-to-NUV range, with negligible astrophysical background. All these features make UV-SCOPE the ideal instrument to study exoplanetary atmospheres and the impact of host stars on their planets. UV-SCOPE was proposed to NASA as a Medium Explorer (MidEx) mission for the 2021 Announcement of Opportunity. If approved, the observatory will be developed over a 5-year period. Its primary science mission takes 34 months to complete. The spacecraft carries enough fuel for 6 years of operations. △ Less

Submitted 19 August, 2022; originally announced August 2022.

Comments: 12 pages, 7 figures, 1 table. Conference presentation, 17 July 2022, SPIE Astronomical Telescopes and Instrumentation, Montreal, Canada

A Temperature Trend for Clouds and Hazes in Exoplanets Atmospheres

Authors: Raissa Estrela, Mark Swain, Gael Roudier

Abstract: The transmission spectra of exoplanet atmospheres observed with the Hubble Space Telescope (HST) in the near-infrared range (1.1-1.65$μ$m) frequently show evidence for some combination of clouds and hazes. Identification of systematic trends in exoplanet clouds and hazes is potentially important for understanding atmospheric composition and temperature structure. Here we report on the analysis of… ▽ More The transmission spectra of exoplanet atmospheres observed with the Hubble Space Telescope (HST) in the near-infrared range (1.1-1.65$μ$m) frequently show evidence for some combination of clouds and hazes. Identification of systematic trends in exoplanet clouds and hazes is potentially important for understanding atmospheric composition and temperature structure. Here we report on the analysis of spectral modulation using a large, uniformly processed sample of HST/WFC3 transit spectra from 62 exoplanets. The spectral retrieval includes the capability to detect and represent atmospheres in which the composition departs from thermochemical equilibrium. By using this unique catalog and measuring the dampening of spectral modulations compared to strictly clear atmospheres, we identify two populations. One is completely cloud/haze free spanning a wide temperature range, while the other population, identified as ``Partial cloud/hazes'', follows a trend from mostly cloudy/hazy around 500~K to mostly clear at $\sim$1500~K. We also find that a partially transparent aerosol component is frequently present and that it is typically vertically distributed throughout the atmospheric column. Our findings also suggest that while clouds and hazes are common in exoplanet atmospheres, the majority of planets have some level of detectable spectral modulation. Additionally, the empirical trend that clouds and hazes are minimized at 1460.86K$^{+316}_{-405}$ revealed in our catalog has predictive utility for modelling the performance of large-scale transiting exoplanets survey, such as planned with the Ariel mission. This trend can also be used for making a probability-based forecast of spectral modulation for a given source in the context of future JWST observations. Future observations including the optical and/or a broader spectral coverage may be useful to further quantify the trend reported here. △ Less

Submitted 11 November, 2022; v1 submitted 20 June, 2022; originally announced June 2022.

Comments: 12 pages, 4 figures, accepted for publication in ApjL

Influence of C/O Ratio on Hot Jupiter Atmospheric Chemistry

Authors: Benjamin Fleury, Murthy S. Gudipati, Bryana L. Henderson, Mark Swain

Abstract: We have conducted laboratory experiments to study the chemistry in hot Jupiter atmospheres with C/O ratio of 0.35. We have compared our results with the ones obtained previously for atmospheres with a C/O ratio of 1 to investigate the influence of the C/O ratio on the chemistry and formation of photochemical organic aerosol. We found that the C/O ratio and the gas mixture compositions strongly inf… ▽ More We have conducted laboratory experiments to study the chemistry in hot Jupiter atmospheres with C/O ratio of 0.35. We have compared our results with the ones obtained previously for atmospheres with a C/O ratio of 1 to investigate the influence of the C/O ratio on the chemistry and formation of photochemical organic aerosol. We found that the C/O ratio and the gas mixture compositions strongly influence the pathways responsible for the formation of CO2. Thermochemical reactions are primarily responsible for the formation of CO2 in low C/O ratio atmospheres, while photochemistry is the dominant process in high C/O ratio atmospheres even if the final CO2 concentration is the same in both cases. Our results show that low C/O atmospheres at the thermochemical equilibrium contain a higher water abundance, while high C/O atmospheres are significantly depleted in water. However, in low C/O atmospheres, the water abundance is not affected by UV photolysis, while our previous work demonstrated that significant amount of water can be produced in high C/O ratio atmospheres. This contrast in water production suggests that photochemistry should be considered when interpreting exoplanet transit spectra. Finally, we did not observe the formation of a detectable amount of non-volatile photochemical aerosols in low C/O atmospheres, in contrast to our previous study. We infer that for C/O ratio < 1, water likely inhibits organic growth and aerosol formation, suggesting that photochemical organic aerosols are likely to be observed in planets presenting a carbon enrichment compared to their host stars. △ Less

Submitted 14 April, 2022; originally announced April 2022.

Comments: 23 pages, 3 tables, 6 figures

Journal ref: The Astrophysical Journal, 899:147 (10pp), 2020 August 20

A New Analysis of 8 Spitzer Phase Curves and Hot Jupiter Population Trends: Qatar-1b, Qatar-2b, WASP-52b, WASP-34b, and WASP-140b

Authors: Erin May, Kevin Stevenson, Jacob Bean, Taylor Bell, Nicolas Cowan, Lisa Dang, Jean-Michel Desert, Jonathan Fortney, Dylan Keating, Eliza Kempton, Thaddeus Komacek, Nikole Lewis, Megan Mansfield, Caroline Morley, Vivien Parmentier, Emily Rauscher, Mark Swain, Robert Zellem, Adam Showman

Abstract: With over 30 phase curves observed during the warm Spitzer mission, the complete data set provides a wealth of information relating to trends and three-dimensional properties of hot Jupiter atmospheres. In this work we present a comparative study of seven new Spitzer phase curves for four planets with equilibrium temperatures of T$_{eq}\sim$ 1300K: Qatar-2b, WASP-52b, WASP-34b, and WASP-140b, as w… ▽ More With over 30 phase curves observed during the warm Spitzer mission, the complete data set provides a wealth of information relating to trends and three-dimensional properties of hot Jupiter atmospheres. In this work we present a comparative study of seven new Spitzer phase curves for four planets with equilibrium temperatures of T$_{eq}\sim$ 1300K: Qatar-2b, WASP-52b, WASP-34b, and WASP-140b, as well as the reanalysis of the 4.5 $\micron$ Qatar-1b phase curve due to the similar equilibrium temperature. In total, five 4.5 $\micron$ phase curves and three 3.6 $\micron$ phase curves are analyzed here with a uniform approach. Using these new results, in combination with literature values for the entire population of published Spitzer phase curves of hot Jupiters, we present evidence for a linear trend of increasing hot spot offset with increasing orbital period, as well as observational evidence for two classes of planets in apparent redistribution vs. equilibrium temperature parameter space, and tentative evidence for a dependence of hot spot offset on planetary surface gravity in our $\sim$ 1300 K sample. We do not find trends in apparent heat redistribution with orbital period or gravity. Non-uniformity in literature Spitzer data analysis techniques precludes a definitive determination of the sources or lack of trends. △ Less

Submitted 28 March, 2022; originally announced March 2022.

Comments: 22 pages, 13 figures, 6 tables. Accepted for publication in AAS journals

Photochemistry in hot H2-dominated exoplanet atmospheres

Authors: Benjamin Fleury, Murthy S. Gudipati, Bryana L. Henderson, Mark Swain

Abstract: Photochemistry has the potential to substantially impact the atmospheric composition of exoplanets with consequences on the radiative transfer, thermal structure and dynamics of the atmospheres, particularly in UV-rich stellar environments. Here, we present the results of a first laboratory experimental simulation of photochemistry in carbon-rich exoplanet atmospheres at elevated temperatures. Evo… ▽ More Photochemistry has the potential to substantially impact the atmospheric composition of exoplanets with consequences on the radiative transfer, thermal structure and dynamics of the atmospheres, particularly in UV-rich stellar environments. Here, we present the results of a first laboratory experimental simulation of photochemistry in carbon-rich exoplanet atmospheres at elevated temperatures. Evolution of gas-phase molecular composition was quantitatively monitored with infrared spectroscopy and mass spectrometry. We found that H2/CO gas compositions can change significantly from thermal equilibria compositions when irradiated with Lyman-alpha photons at temperatures ranging from 600 K to 1500 K. Carbon dioxide and water were found to be the main products caused by photolysis, while formation of methane was also observed to a lesser extent. We find that photochemistry efficiency is strongly correlated with increasing temperature. Our finding that water is efficiently produced by photochemistry in a super Solar C/O=1 environment, representing C enhancement relative to solar values C/O ratio = 0.54, has significant implications for the interpretation of many exoplanet transmission spectra. We also find the formation of an organic solid condensate at 1500 K and under Lyman-alpha UV-radiation, confirming the possibility of forming photochemical hazes in hot-Jupiter exoplanet atmospheres with an enhanced C/O ratio compared to Solar. △ Less

Submitted 16 February, 2022; originally announced February 2022.

Comments: 32 pages, 3 tables, 10 figures

Journal ref: The Astrophysical Journal, 871:158 (14pp), 2019 February 1

Generation and entanglement study of generalized N-mode single photon perfect W-states

Authors: Manoranjan Swain, M. Karthick Selvan, Amit Rai, Prasanta K. Panigrahi

Abstract: We consider single photon realization of generalized N-qubit perfect W-states which are suitable for perfect teleportation and superdense coding. We propose schemes to generate generalized N-mode single photon perfect W-states and derive entanglement conditions which for single photon states require finding fidelity with generalized N-mode single photon perfect W-states and hence more suitable to… ▽ More We consider single photon realization of generalized N-qubit perfect W-states which are suitable for perfect teleportation and superdense coding. We propose schemes to generate generalized N-mode single photon perfect W-states and derive entanglement conditions which for single photon states require finding fidelity with generalized N-mode single photon perfect W-states and hence more suitable to detect the genuine entanglement of generalized perfect W-states. Based on the evolution of single photon wavefunction in scalable integrated photonic lattices, we present schemes for the preparation of generalized N-mode single photon perfect W-states at desired propagation distance. The integrated waveguide structures can precisely be fabricated, offer low photon propagation losses and can be integrated on a chip. We consider both planar and ring type waveguide structures for state generation. We derive set of generalized entanglement conditions using the sum uncertainty relations of generalized su(2) algebra operators. We show that any given genuinely entangled N-mode single photon state is a squeezed state of a specific su(2) algebra operator and can be expressed as superposition of a pair of orthonormal generalized N-mode single photon perfect W-states which are eigenstates of that specific su(2) algebra operator. Within the single photon subspace, the eigendecomposition of su(2) algebra operators reduces the generalized entanglement condition to a simplified single photon separability condition. In order to verify the entanglement of given genuinely entangled N-mode single photon state using this condition one has to find the difference between the state fidelities with suitably chosen pair of orthonormal generalized N-mode single photon perfect W-states. Finally, we propose an experimental scheme to verify the entanglement using the proposed conditions... △ Less

Submitted 31 July, 2022; v1 submitted 8 December, 2021; originally announced December 2021.

Comments: 12 pages, 4 figures

Journal ref: Quantum Inf Process 22, 302 (2023)

Onboard Dynamic Image Exposure Control for the Star-Planet Activity Research CubeSat (SPARCS)

Authors: Tahina Ramiaramanantsoa, Judd D. Bowman, Evgenya L. Shkolnik, R. O. Parke Loyd, David R. Ardila, April Jewell, Travis Barman, Christophe Basset, Matthew Beasley, Samuel Cheng, Johnathan Gamaunt, Varoujan Gorjian, John Hennessy, Daniel Jacobs, Logan Jensen, Mary Knapp, Joe Llama, Victoria Meadows, Shouleh Nikzad, Sarah Peacock, Paul Scowen, Mark R. Swain

Abstract: The Star-Planet Activity Research CubeSat (SPARCS) is a 6U CubeSat under development to monitor the flaring and chromospheric activity of M dwarfs at near-ultraviolet (NUV) and far-ultraviolet (FUV) wavelengths. The spacecraft hosts two UV-optimized delta-doped charge-coupled devices fed by a 9-cm telescope and a dichroic beam splitter. A dedicated science payload processor performs near real-time… ▽ More The Star-Planet Activity Research CubeSat (SPARCS) is a 6U CubeSat under development to monitor the flaring and chromospheric activity of M dwarfs at near-ultraviolet (NUV) and far-ultraviolet (FUV) wavelengths. The spacecraft hosts two UV-optimized delta-doped charge-coupled devices fed by a 9-cm telescope and a dichroic beam splitter. A dedicated science payload processor performs near real-time onboard science image processing to dynamically change detector integration times and gains to reduce the occurrence of pixel saturation during strong M dwarf flaring events and provide adequate flare light curve structure resolution while enabling the detection of low-amplitude rotational modulation. The processor independently controls the NUV and FUV detectors. For each detector, it derives control updates from the most recent completed exposure and applies them to the next exposure. The detection of a flare event in the NUV channel resets the exposure in the FUV channel with new exposure parameters. Implementation testing of the control algorithm using simulated light curves and full-frame images demonstrates a robust response to the quiescent and flaring levels expected for the stars to be monitored by the mission. The SPARCS onboard autonomous exposure control algorithm is adaptable for operation in future point source-targeting space-based and ground-based observatories geared towards the monitoring of extreme transient astrophysics phenomena. △ Less

Submitted 19 November, 2021; originally announced November 2021.

Comments: 11 pages, 8 figures; Monthly Notices of the Royal Astronomical Society (MNRAS), in press

Characterization of an Instrument Model for Exoplanet Transit Spectrum Estimation through Wide Scale Analysis on HST Data

Authors: Noah Huber-Feely, Mark R. Swain, Gael Roudier, Raissa Estrela

Abstract: Instrument models (IMs) enable the reduction of systematic error in transit spectroscopy light curve data, but, since the model formulation can influence the estimation of science model parameters, characterization of the instrument model effects is crucial to the interpretation of the reduced data. We analyze a simple instrument model and assess its validity and performance across Hubble WFC3 and… ▽ More Instrument models (IMs) enable the reduction of systematic error in transit spectroscopy light curve data, but, since the model formulation can influence the estimation of science model parameters, characterization of the instrument model effects is crucial to the interpretation of the reduced data. We analyze a simple instrument model and assess its validity and performance across Hubble WFC3 and STIS instruments. Over a large, n=63, sample of observed targets, an MCMC sampler computes the parent distribution of each instrument model parameter. Possible parent distribution functions are then fit and tested against the empirical IM distribution. Correlation and other analyses are then performed to find IM relationships. The model is shown to perform well across the 2 instruments and 3 filters analyzed and, further, the Student's t-distribution is shown to closely fit the empirical parent distribution of IM parameters and the Gaussian is shown to poorly model the observed distribution. This parent distribution can be used in the MCMC prior fitting and demonstrates IM consistency for wide scale atmospheric analysis using this model. Finally, we propose a simple metric based on light curve residuals to determine model performance, and we demonstrate its ability to determine whether a derived spectrum under this IM is high quality and robust. △ Less

Submitted 13 November, 2021; originally announced November 2021.

Comments: 19 pages, 14 figures, accepted for publication in Astronomical Journal

The fundamentals of Lyman-alpha exoplanet transits

Authors: James E. Owen, Ruth A. Murray-Clay, Ethan Schreyer, Hilke E. Schlichting, David Ardila, Akash Gupta, R. O. Parke Loyd, Evgenya L. Shkolnik, David K. Sing, Mark R. Swain

Abstract: Lyman-$α$ transits have been detected from several nearby exoplanets and are one of our best insights into the atmospheric escape process. However, due to ISM absorption, we typically only observe the transit signature in the blue-wing, making them challenging to interpret. This challenge has been recently highlighted by non-detections from planets thought to be undergoing vigorous escape. Pioneer… ▽ More Lyman-$α$ transits have been detected from several nearby exoplanets and are one of our best insights into the atmospheric escape process. However, due to ISM absorption, we typically only observe the transit signature in the blue-wing, making them challenging to interpret. This challenge has been recently highlighted by non-detections from planets thought to be undergoing vigorous escape. Pioneering 3D simulations have shown that escaping hydrogen is shaped into a cometary tail receding from the planet. Motivated by this work, we develop a simple model to interpret Lyman-$α$ transits. Using this framework, we show that the Lyman-$α$ transit depth is primarily controlled by the properties of the stellar tidal field rather than details of the escape process. Instead, the transit duration provides a direct measurement of the velocity of the planetary outflow. This result arises because the underlying physics is the distance a neutral hydrogen atom can travel before it is photoionized in the outflow. Thus, higher irradiation levels, expected to drive more powerful outflows, produce weaker, shorter Lyman-$α$ transits because the outflowing gas is ionized more quickly. Our framework suggests that the generation of energetic neutral atoms may dominate the transit signature early, but the acceleration of planetary material produces long tails. Thus, Lyman-$α$ transits do not primarily probe the mass-loss rates. Instead, they inform us about the velocity at which the escape mechanism is ejecting material from the planet, providing a clean test of predictions from atmospheric escape models. △ Less

Submitted 18 November, 2022; v1 submitted 11 November, 2021; originally announced November 2021.

Comments: Accepted for publication in MNRAS

Time-Resolved Photometry of the High-Energy Radiation of M Dwarfs with the Star-Planet Activity Research CubeSat (SPARCS)

Authors: Tahina Ramiaramanantsoa, Judd D. Bowman, Evgenya L. Shkolnik, R. O. Parke Loyd, David R. Ardila, Travis Barman, Christophe Basset, Matthew Beasley, Samuel Cheng, Johnathan Gamaunt, Varoujan Gorjian, Daniel Jacobs, Logan Jensen, April Jewell, Mary Knapp, Joe Llama, Victoria Meadows, Shouleh Nikzad, Sarah Peacock, Paul Scowen, Mark R. Swain

Abstract: Know thy star, know thy planet,... especially in the ultraviolet (UV). Over the past decade, that motto has grown from mere wish to necessity in the M dwarf regime, given that the intense and highly variable UV radiation from these stars is suspected of strongly impacting their planets' habitability and atmospheric loss. This has led to the development of the Star-Planet Activity Research CubeSat… ▽ More Know thy star, know thy planet,... especially in the ultraviolet (UV). Over the past decade, that motto has grown from mere wish to necessity in the M dwarf regime, given that the intense and highly variable UV radiation from these stars is suspected of strongly impacting their planets' habitability and atmospheric loss. This has led to the development of the Star-Planet Activity Research CubeSat (SPARCS), a NASA-funded 6U CubeSat observatory fully devoted to the photometric monitoring of the UV flaring of M dwarfs hosting potentially habitable planets. The SPARCS science imaging system uses a 9-cm telescope that feeds two delta-doped UV-optimized CCDs through a dichroic beam splitter, enabling simultaneous monitoring of a target field in the near-UV and far-UV. A dedicated onboard payload processor manages science observations and performs near-real time image processing to sustain an autonomous dynamic exposure control algorithm needed to mitigate pixel saturation during flaring events. The mission is currently half-way into its development phase. We present an overview of the mission's science drivers and its expected contribution to our understanding of star-planet interactions. We also present the expected performance of the autonomous dynamic exposure control algorithm, a first-of-its-kind on board a space-based stellar astrophysics observatory. △ Less

Submitted 3 November, 2021; originally announced November 2021.

Comments: 6 pages, 4 figures, Accepted for publication in Astronomische Nachrichten

A unique hot Jupiter spectral sequence with evidence for compositional diversity

Authors: Megan Mansfield, Michael R. Line, Jacob L. Bean, Jonathan J. Fortney, Vivien Parmentier, Lindsey Wiser, Eliza M. -R. Kempton, Ehsan Gharib-Nezhad, David K. Sing, Mercedes López-Morales, Claire Baxter, Jean-Michel Désert, Mark R. Swain, Gael M. Roudier

Abstract: The emergent spectra of close-in, giant exoplanets ("hot Jupiters") are expected to be distinct from those of self-luminous objects with similar effective temperatures because hot Jupiters are primarily heated from above by their host stars rather than internally from the release of energy from their formation. Theoretical models predict a continuum of dayside spectra for hot Jupiters as a functio… ▽ More The emergent spectra of close-in, giant exoplanets ("hot Jupiters") are expected to be distinct from those of self-luminous objects with similar effective temperatures because hot Jupiters are primarily heated from above by their host stars rather than internally from the release of energy from their formation. Theoretical models predict a continuum of dayside spectra for hot Jupiters as a function of irradiation level, with the coolest planets having absorption features in their spectra, intermediate-temperature planets having emission features due to thermal inversions, and the hottest planets having blackbody-like spectra due to molecular dissociation and continuum opacity from the H- ion. Absorption and emission features have been detected in the spectra of a number of individual hot Jupiters, and population-level trends have been observed in photometric measurements. However, there has been no unified, population-level study of the thermal emission spectra of hot Jupiters such as has been done for cooler brown dwarfs and transmission spectra of hot Jupiters. Here we show that hot Jupiter secondary eclipse spectra centered around a water absorption band at 1.4 microns follow a common trend in water feature strength with temperature. The observed trend is broadly consistent with model predictions for how the thermal structures of solar-composition planets vary with irradiation level. Nevertheless, the ensemble of planets exhibits some degree of scatter around the mean trend for solar composition planets. The spread can be accounted for if the planets have modest variations in metallicity and/or elemental abundance ratios, which is expected from planet formation models. (abridged abstract) △ Less

Submitted 21 October, 2021; originally announced October 2021.

Comments: 24 pages, 8 figures, published in Nature Astronomy

Detection of Aerosols at Microbar Pressures in an Exoplanet Atmosphere

Authors: Raissa Estrela, Mark Swain, Gael Roudier, Robert West, Elyar Sedaghati, Adriana Valio

Abstract: Formation of hazes at microbar pressures has been explored by theoretical models of exoplanet atmospheres to explain Rayleigh scattering and/or featureless transmission spectra, however observational evidence of aerosols in the low pressure formation environments has proved elusive. Here, we show direct evidence of aerosols existing at $\sim$1 microbar pressures in the atmosphere of the warm sub-S… ▽ More Formation of hazes at microbar pressures has been explored by theoretical models of exoplanet atmospheres to explain Rayleigh scattering and/or featureless transmission spectra, however observational evidence of aerosols in the low pressure formation environments has proved elusive. Here, we show direct evidence of aerosols existing at $\sim$1 microbar pressures in the atmosphere of the warm sub-Saturn WASP-69b using observations taken with Space Telescope Imaging Spectrograph (STIS) and Wide Field Camera 3 (WFC3) instruments on the Hubble Space Telescope. The transmission spectrum shows a wavelength-dependent slope induced by aerosol scattering that covers 11 scale heights of spectral modulation. Drawing on the extensive studies of haze in our Solar System, we model the transmission spectrum based on a scaled version of Jupiter's haze density profile to show that WASP-69b transmission spectrum can be produced by scattering from an approximately constant density of particles extending throughout the atmospheric column from 40 millibar to microbar pressures. These results are consistent with theoretical expectations based on microphysics of the aerosol particles that have suggested haze can exist at microbar pressures in exoplanet atmospheres. △ Less

Submitted 9 July, 2021; v1 submitted 18 June, 2021; originally announced June 2021.

Comments: 15 pages, 13 figures, accepted for publication in AJ

Ariel: Enabling planetary science across light-years

Authors: Giovanna Tinetti, Paul Eccleston, Carole Haswell, Pierre-Olivier Lagage, Jérémy Leconte, Theresa Lüftinger, Giusi Micela, Michel Min, Göran Pilbratt, Ludovic Puig, Mark Swain, Leonardo Testi, Diego Turrini, Bart Vandenbussche, Maria Rosa Zapatero Osorio, Anna Aret, Jean-Philippe Beaulieu, Lars Buchhave, Martin Ferus, Matt Griffin, Manuel Guedel, Paul Hartogh, Pedro Machado, Giuseppe Malaguti, Enric Pallé , et al. (293 additional authors not shown)

Abstract: Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was adopted as the fourth medium-class mission in ESA's Cosmic Vision programme to be launched in 2029. During its 4-year mission, Ariel will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths.… ▽ More Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was adopted as the fourth medium-class mission in ESA's Cosmic Vision programme to be launched in 2029. During its 4-year mission, Ariel will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System. The payload consists of an off-axis Cassegrain telescope (primary mirror 1100 mm x 730 mm ellipse) and two separate instruments (FGS and AIRS) covering simultaneously 0.5-7.8 micron spectral range. The satellite is best placed into an L2 orbit to maximise the thermal stability and the field of regard. The payload module is passively cooled via a series of V-Groove radiators; the detectors for the AIRS are the only items that require active cooling via an active Ne JT cooler. The Ariel payload is developed by a consortium of more than 50 institutes from 16 ESA countries, which include the UK, France, Italy, Belgium, Poland, Spain, Austria, Denmark, Ireland, Portugal, Czech Republic, Hungary, the Netherlands, Sweden, Norway, Estonia, and a NASA contribution. △ Less

Submitted 10 April, 2021; originally announced April 2021.

Comments: Ariel Definition Study Report, 147 pages. Reviewed by ESA Science Advisory Structure in November 2020. Original document available at: https://www.cosmos.esa.int/documents/1783156/3267291/Ariel_RedBook_Nov2020.pdf/

Report number: ESA/SCI(2020)1

The TESS Objects of Interest Catalog from the TESS Prime Mission

Authors: Natalia M. Guerrero, S. Seager, Chelsea X. Huang, Andrew Vanderburg, Aylin Garcia Soto, Ismael Mireles, Katharine Hesse, William Fong, Ana Glidden, Avi Shporer, David W. Latham, Karen A. Collins, Samuel N. Quinn, Jennifer Burt, Diana Dragomir, Ian Crossfield, Roland Vanderspek, Michael Fausnaugh, Christopher J. Burke, George Ricker, Tansu Daylan, Zahra Essack, Maximilian N. Günther, Hugh P. Osborn, Joshua Pepper , et al. (80 additional authors not shown)

Abstract: We present 2,241 exoplanet candidates identified with data from the Transiting Exoplanet Survey Satellite (TESS) during its two-year prime mission. We list these candidates in the TESS Objects of Interest (TOI) Catalog, which includes both new planet candidates found by TESS and previously-known planets recovered by TESS observations. We describe the process used to identify TOIs and investigate t… ▽ More We present 2,241 exoplanet candidates identified with data from the Transiting Exoplanet Survey Satellite (TESS) during its two-year prime mission. We list these candidates in the TESS Objects of Interest (TOI) Catalog, which includes both new planet candidates found by TESS and previously-known planets recovered by TESS observations. We describe the process used to identify TOIs and investigate the characteristics of the new planet candidates, and discuss some notable TESS planet discoveries. The TOI Catalog includes an unprecedented number of small planet candidates around nearby bright stars, which are well-suited for detailed follow-up observations. The TESS data products for the Prime Mission (Sectors 1-26), including the TOI Catalog, light curves, full-frame images, and target pixel files, are publicly available on the Mikulski Archive for Space Telescopes. △ Less

Submitted 24 March, 2021; v1 submitted 23 March, 2021; originally announced March 2021.

Comments: 39 pages, 16 figures. The Prime Mission TOI Catalog is included in the ancillary data as a CSV. For the most up-to-date catalog, refer to https://tess.mit.edu/toi-releases/

Detection of an Atmosphere on a Rocky Exoplanet

Authors: Mark R. Swain, Raissa Estrela, Gael M. Roudier, Christophe Sotin, Paul Rimmer, Adriana Valio, Robert West, Kyle Pearson, Noah Huber-Feely, Robert T. Zellem

Abstract: We report the detection of an atmosphere on a rocky exoplanet, GJ 1132 b, which is similar to Earth in terms of size and density. The atmospheric transmission spectrum was detected using Hubble WFC3 measurements and shows spectral signatures of aerosol scattering, HCN, and CH$_{4}$ in a low mean molecular weight atmosphere. We model the atmospheric loss process and conclude that GJ 1132 b likely l… ▽ More We report the detection of an atmosphere on a rocky exoplanet, GJ 1132 b, which is similar to Earth in terms of size and density. The atmospheric transmission spectrum was detected using Hubble WFC3 measurements and shows spectral signatures of aerosol scattering, HCN, and CH$_{4}$ in a low mean molecular weight atmosphere. We model the atmospheric loss process and conclude that GJ 1132 b likely lost the original H/He envelope, suggesting that the atmosphere that we detect has been reestablished. We explore the possibility of H$_{2}$ mantle degassing, previously identified as a possibility for this planet by theoretical studies, and find that outgassing from ultrareduced magma could produce the observed atmosphere. In this way we use the observed exoplanet transmission spectrum to gain insights into magma composition for a terrestrial planet. The detection of an atmosphere on this rocky planet raises the possibility that the numerous powerfully irradiated Super-Earth planets, believed to be the evaporated cores of Sub-Neptunes, may, under favorable circumstances, host detectable atmospheres. △ Less

Submitted 9 March, 2021; originally announced March 2021.

Comments: 22 pages, 12 figures, accepted for publication in Astronomical Journal

Non classical light in Jx photonic lattice

Authors: Manoranjan Swain, Amit Rai

Abstract: We report the study of non-classical light in a photonic lattice having parabolic coupling distribution, also known as Jx photonic lattice. We focus on two photon Fock state, two photon N00N state, and single mode squeezed state along with coherent state as input to the lattice. We investigate the possibility of perfect transfer of mean photon number as well as quantum state from one waveguide mod… ▽ More We report the study of non-classical light in a photonic lattice having parabolic coupling distribution, also known as Jx photonic lattice. We focus on two photon Fock state, two photon N00N state, and single mode squeezed state along with coherent state as input to the lattice. We investigate the possibility of perfect transfer of mean photon number as well as quantum state from one waveguide mode to other. We study photon-photon correlation for two photon N00N state. For single mode squeezed state we study in detail, the evolution of squeezing factor and entanglement between the waveguide modes. Our findings suggest perfect transfer of average photon number for all cases and perfect transfer of quantum state in case of two photon Fock state and two photon N00N state only and not in the case of squeezed and coherent state. Our results should have applications in physical implementation of photonic continuous variable quantum information processing. △ Less

Submitted 14 January, 2021; v1 submitted 28 December, 2020; originally announced December 2020.

Comments: 14 pages,8 figures, Comments are welcome

A Comprehensive Reanalysis of $\textit{Spitzer}$'s 4.5 $μ$m Phase Curves, and the Phase Variations of the Ultra-hot Jupiters MASCARA-1b and KELT-16b

Authors: Taylor J. Bell, Lisa Dang, Nicolas B. Cowan, Jacob Bean, Jean-Michel Désert, Jonathan J. Fortney, Dylan Keating, Eliza Kempton, Laura Kreidberg, Michael R. Line, Megan Mansfield, Vivien Parmentier, Kevin B. Stevenson, Mark Swain, Robert T. Zellem

Abstract: We have developed an open-source pipeline for the analysis of \textit{Spitzer}/IRAC channel 1 and 2 time-series photometry, incorporating some of the most popular decorrelation methods. We applied this pipeline to new phase curve observations of ultra-hot Jupiters MASCARA-1b and KELT-16b, and we performed the first comprehensive reanalysis of 15 phase curves. We find that MASCARA-1b and KELT-16b h… ▽ More We have developed an open-source pipeline for the analysis of \textit{Spitzer}/IRAC channel 1 and 2 time-series photometry, incorporating some of the most popular decorrelation methods. We applied this pipeline to new phase curve observations of ultra-hot Jupiters MASCARA-1b and KELT-16b, and we performed the first comprehensive reanalysis of 15 phase curves. We find that MASCARA-1b and KELT-16b have phase offsets of $6^{+11}_{-11}~^{\circ}$W and $38^{+16}_{-15}~^{\circ}$W, dayside temperatures of $2952^{+100}_{-97}$ K and $3070^{+160}_{-150}$ K, and nightside temperatures of $1300^{+340}_{-340}$ K and $1900^{+430}_{-440}$ K, respectively. We confirm a strong correlation between dayside and irradiation temperatures with a shallower dependency for nightside temperature. We also find evidence that the normalized phase curve amplitude (peak-to-trough divided by eclipse depth) is correlated with stellar effective temperature. In addition, while our different models often retrieve similar parameters, significant differences occasionally arise between them, as well as between our preferred model and the literature values. Nevertheless, our preferred models are consistent with published phase offsets to within $-8\pm21$ degrees ($-1.6\pm3.2$ sigma), and normalized phase curve amplitudes are on average reproduced to within $-0.01\pm0.24$ ($-0.1\pm1.6$ sigma). Finally, we find that BLISS performs best in most cases, but not all; we therefore recommend future analyses consider numerous detector models to ensure an optimal fit and to assess model dependencies. △ Less

Submitted 25 February, 2021; v1 submitted 1 October, 2020; originally announced October 2020.

Comments: Resubmitted to MNRAS after revision on February 25, 2021, originally submitted to MNRAS on October 1, 2020. 20 pages, 12 figures, and 5 tables. 3 pages of appendix, 16 pages of supplementary information

Generation of perfect W-state and demonstration of its application to quantum information splitting

Authors: Manoranjan Swain, Vipin Devrari, Amit Rai, Bikash K. Behera, Prasanta K. Panigrahi

Abstract: We report the first experimental realization of perfect W-state in a superconducting qubit based system. In contrast to maximally entangled state, the perfect W state is different in weights and phases of the terms contained in the maximally entangled W-state. The prefect W state finds important applications in quantum information processing tasks such as perfect teleportation, superdense coding,… ▽ More We report the first experimental realization of perfect W-state in a superconducting qubit based system. In contrast to maximally entangled state, the perfect W state is different in weights and phases of the terms contained in the maximally entangled W-state. The prefect W state finds important applications in quantum information processing tasks such as perfect teleportation, superdense coding, secret sharing etc. The efficiency of generation is quantified by fidelity which is calculated by performing full quantum state tomography. To verify the presence of genuine nonlocality in the generated state, we experimentally perform Mermin's inequality tests. Further, we have also demonstrated splitting and sharing of quantum information using the experimentally generated state. △ Less

Submitted 2 June, 2020; originally announced June 2020.

Comments: 12 pages, 7 figures, Comments are welcome

Single photon generation and non-locality of perfect W-state

Authors: Manoranjan Swain, Amit Rai, M. Karthick Selvan, Prasanta K. Panigrahi

Abstract: We study the generation of single photon perfect W-state. An important aspect of this perfect W-state is that, it can be used for perfect teleportation and superdense coding, which are not achievable with maximally entangled W-state. Our scheme for generation involves entanglement between various path degrees of freedom of a single photon in a compact and weakly coupled integrated waveguide system… ▽ More We study the generation of single photon perfect W-state. An important aspect of this perfect W-state is that, it can be used for perfect teleportation and superdense coding, which are not achievable with maximally entangled W-state. Our scheme for generation involves entanglement between various path degrees of freedom of a single photon in a compact and weakly coupled integrated waveguide system, which can be fabricated precisely with femtosecond laser direct writing technique. These platforms are interferometrically stable, scalable, less sensitive to decoherence and ensures a very low loss factor of 0.1dB/cm during photon propagation and hence are ideal for generation of perfect W-state. In addition to generation of single photon perfect W-state we study its non local properties using theory of local elements of reality. △ Less

Submitted 29 April, 2020; originally announced May 2020.

Comments: 7 pages, 6 figures, Comments are welcome

Utilizing Small Telescopes Operated by Citizen Scientists for Transiting Exoplanet Follow-up

Authors: Robert T. Zellem, Kyle A. Pearson, Ethan Blaser, Martin Fowler, David R. Ciardi, Anya Biferno, Bob Massey, Franck Marchis, Robert Baer, Conley Ball, Mike Chasin, Mike Conley, Scott Dixon, Elizabeth Fletcher, Saneyda Hernandez, Sujay Nair, Quinn Perian, Frank Sienkiewicz, Kalee Tock, Vivek Vijayakumar, Mark R. Swain, Gael M. Roudier, Geoffrey Bryden, Dennis M. Conti, Dolores H. Hill , et al. (19 additional authors not shown)

Abstract: Due to the efforts by numerous ground-based surveys and NASA's Kepler and TESS, there will be hundreds, if not thousands, of transiting exoplanets ideal for atmospheric characterization via spectroscopy with large platforms such as JWST and ARIEL. However their next predicted mid-transit time could become so increasingly uncertain over time that significant overhead would be required to ensure the… ▽ More Due to the efforts by numerous ground-based surveys and NASA's Kepler and TESS, there will be hundreds, if not thousands, of transiting exoplanets ideal for atmospheric characterization via spectroscopy with large platforms such as JWST and ARIEL. However their next predicted mid-transit time could become so increasingly uncertain over time that significant overhead would be required to ensure the detection of the entire transit. As a result, follow-up observations to characterize these exoplanetary atmospheres would require less-efficient use of an observatory's time---which is an issue for large platforms where minimizing observing overheads is a necessity. Here we demonstrate the power of citizen scientists operating smaller observatories ($\le$1-m) to keep ephemerides "fresh", defined here as when the 1$σ$ uncertainty in the mid-transit time is less than half the transit duration. We advocate for the creation of a community-wide effort to perform ephemeris maintenance on transiting exoplanets by citizen scientists. Such observations can be conducted with even a 6-inch telescope, which has the potential to save up to $\sim$10,000~days for a 1000-planet survey. Based on a preliminary analysis of 14 transits from a single 6-inch MicroObservatory telescope, we empirically estimate the ability of small telescopes to benefit the community. Observations with a small-telescope network operated by citizen scientists are capable of resolving stellar blends to within 5''/pixel, can follow-up long period transits in short-baseline TESS fields, monitor epoch-to-epoch stellar variability at a precision 0.67\%$\pm$0.12\% for a 11.3 V-mag star, and search for new planets or constrain the masses of known planets with transit timing variations greater than two minutes. △ Less

Submitted 19 May, 2020; v1 submitted 19 March, 2020; originally announced March 2020.

Comments: 26 pages, 15 figures; published in PASP

Journal ref: Publications of the Astronomical Society of the Pacific, May 2020, Volume 132, Issue 1011, id.054401Publications of the Astronomical Society of the Pacific, Volume 132, Issue 1011, id.054401