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Certain astronomy problems, such as the probabilistic cross-matching algorithms of Wilson & Naylor, require descriptions of galaxy counts as a function of brightness in many different filter sets, for which we often lack dedicated observations. With this motivation in mind, I present a simple model for calculating differential galaxy counts for an arbitrary bandpass or wavelength. The model uses a double Schechter function to describe the number density of galaxies as a function of absolute magnitude, including redshift-driven galaxy evolution, for both “blue” and “red” galaxy types. Collating previously derived values for the parameterization of the evolving Schechter function— M 0 * , ϕ 0 * , P, Q, and α—I fit the dependencies of these parameters as a function of wavelength, allowing for the tabulation of differential galaxy counts in a new filter for which observations are unavailable. Finally, I briefly compare the model with some differential galaxy counts obtained from the literature.

In exoplanet atmosphere analyses, a suite of retrievals, with and without different chemical components, is often run, with forward models generated across their parameter space. I discuss here potential pitfalls in the interpretation of the statistics of such setups, suggesting a few simple tests to consider when interpreting their results.

To ensure robust constraints are placed on exoplanet atmospheric transmission spectra, future observations need to obtain high signal-to-noise ratio (SNR) measurements assuming smaller amplitude molecular signatures than those of clear solar metallicity atmospheres. Analyzing 37 exoplanet transmission spectra we find clear solar molecular features are measured in, Published by RNAAS January 2019, Volume 3, Issue 1