arXiv subjects

Corey Spohn

Publications and source records attributed to Corey Spohn.

4 recordsLinked to original sources

arXiv2026

pyEDITH: the coronagraphic exposure time calculator for the Habitable Worlds Observatory

To support the development of next-generation missions for the search and characterization of habitable planets, high-fidelity tools for astrophysical and instrumental noise simulations are needed. In this paper, we introduce pyEDITH, the Python-based coronagraphic exposure time calculator built for the next recommended NASA flagship mission, the Habitable Worlds Observatory (HWO), tasked with searching for signs of habitability and life in dozens of nearby exoplanet systems. pyEDITH is designed to simulate wavelength-dependent exposure times and signal-to-noise ratios (S/N) for synthetic HWO direct imaging observations, considering realistic engineering specifications and user-defined target information. Its modular architecture ensures flexibility as mission requirements evolve. pyEDITH enables a streamlined integration with modern astronomical workflows and was designed to be used by the scientific community at all skill levels for understanding the capabilities and limitations of different HWO architectures for exoplanet analyses. The code has been validated against existing exposure time calculators and released open-source on GitHub and Zenodo, as well as made accessible through a Graphical User Interface. The pyEDITH package includes API documentation, tutorial notebooks, and has been used in forthcoming scientific publications.

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arXiv2026

Understanding HWO's Field of Regard and Characterization Requirement Trade Space with a Dynamic Observation Scheduling Algorithm

The Habitable Worlds Observatory (HWO) aims to image and characterize at least 25 ExoEarth candidates (EECs). Achieving this goal requires a detailed understanding of the observatory's design trade space, including the operational efficiency of the EEC survey. This study quantifies the impact of two critical parameters: the instantaneous field of regard (FoR) and the number of characterization observations required per EEC ($N_\text{char}$). We introduce a novel dynamic scheduling algorithm implemented within the EXOSIMS framework that models information gain during the mission. The scheduler models the orbital information known about each planet and forecasts detection probabilities to make scheduling decisions. We explore a multi-dimensional trade space, varying aperture size (6.5 m and 8.0 m), dedicated EEC survey time (2.5, 5.0, 7.5 years), $N_\text{char}$ (1 to 4), and FoR ($15^\circ$ to $135^\circ$). Our results demonstrate that the FoR is a major driver of the mission yield, with the yield decreasing significantly when the FoR is less than $90^\circ$. We find that increasing $N_\text{char}$ imposes a significant cost to mission yield, as each additional characterization required reduces yield by approximately 22%. The cumulative impact of requiring four characterizations instead of one lowers the yield by approximately 52%. This harsh penalty can be partially mitigated by increasing the survey duration. The relative yield loss when increasing $N_\text{char}$ from 1 to 2 is 38% for a 2.5 year survey and 14% for a 7.5 year survey. Our results highlight the complex interactions between HWO's engineering constraints and science requirements, and emphasize that the EEC survey efficiency is a critical component of HWO's design space.

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arXiv2026

Characterizing Earth analogs may require a moderate or high-resolution spectrograph

A primary goal of the Habitable Worlds Observatory (HWO) is to detect and measure the abundance of biosignature molecules, such as water (H2O) and oxygen (O2), in the atmosphere of Earth analogs. This is expected to require deep spectroscopic observations lasting hundreds of hours per planet. In this context, it is essential to optimize the spectral resolution of the spectrograph to both maximize the number of planets that can be studied over the lifetime of the mission, and also to reduce the risks of false detections. The purpose of this work is to provide a framework to explore the spectral resolution design trade-space for HWO. This framework must be valid and comparable across all spectral resolutions from low (R<100) to high resolutions (R>10,000), and account for the spectral correlation of the residual starlight (i.e., speckle noise chromaticity). Leveraging the concept of "template matching", we develop a simulation toolkit based on the Python package EXOSIMS to compute the detection significance of planets and molecules. We then simulate observations of Earth analogs around 164 stars using representative mission parameters to explore the effects of the detector noise and the correlated speckle noise floor. Our findings suggest that a moderate or high resolution spectrograph (R>1,000) will provide higher sensitivity to critical molecules compared to a low resolution spectroscopy mode (e.g., R~140). The correlated speckle noise may also entirely suppress our ability to detect bio-signatures at low spectral resolutions. We conclude that a more comprehensive study combined with detailed models of its stability, and other sources of correlated noise, is necessary to fully explore the trade space of spectral resolution and detectability of key species.

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arXiv2025

yieldplotlib: A unified library for exoplanet yield code visualizations

NASA's next flagship observatory, the Habitable Worlds Observatory (HWO), aims to detect and charaterize ~25 habitable zone planets. The total number of habitable zone planets detected is referred to as the exo-Earth "yield'' and accurate yield estimates will be critically important to the mission's success. Tools like the Altruistic Yield Optimizer (AYO) and EXOSIMS provide these yield estimates but differ in language, methods, and outputs. yieldplotlib provides a unified library that can visualize the inputs and outputs of these yield codes in a complete, descriptive, and accessible way.

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