Weak Lensing in the Blue: A Counter-intuitive Strategy for Stratospheric Observations

Abstract The statistical power of weak lensing measurements is principally driven by the number high-redshift galaxies whose shapes are resolved. Conventional wisdom and physical intuition suggest this optimized deep imaging at long (red or near-IR) wavelengths, to avoid losing redshifted Balmer-break Lyman-break galaxies. We use synthetic Emission Line (“EL”)-COSMOS catalog simulate observations using different filters, from various altitudes. Here were predict exposures achieve a target z ≳ 0.3 source density, off-the-shelf custom filters. Ground-based easily better red as (more narrowly) space-based observations. However, we find that SuperBIT , diffraction-limited observatory operating in stratosphere, should instead perform its lensing-quality blue wavelengths.