Explain discrepancies between AYO and EXOSIMS yield calculations

Determine the differences and their causes between exoplanet yield predictions produced by the Altruistic Yield Optimizer and the Exoplanet Open-Source Imaging Mission Simulator, particularly the discrepancies in absolute yield magnitudes for molecular characterization at different wavelengths.

Background

The paper compares AYO and EXOSIMS predictions for H2O and joint H2O–O2 characterization. Although the two tools show broadly similar relative wavelength trends, their calculated total yields differ substantially, and the preferred wavelength for dual characterization is not fully consistent between the tools.

Resolving these discrepancies would improve confidence in yield forecasts and support the use of the calculations for HWO instrument-design and survey-strategy decisions. The paper explicitly defers a dedicated cross-validation investigation.

References

While other works have aimed to benchmark these and other yield exposure time calculators , we leave further investigation of these differences and their causes to future works.

— Possible Observational Survey Strategies to Maximize Exoplanet Yields: A Report from the Survey Strategies Task Group in the Exoplanet Science Yields Working Group  (2609.25540 - Latouf et al., 22 Sep 2026) in Section 4.1, “Normalized Yields Over Wavelength”