DESTINY: The dark energy space telescope

Abstract

The Dark Energy Space Telescope (DESTINY) is an all-grism NIR 1.8 m survey camera optimized to return richly sampled Hubble diagrams of Type Ia and Type II supernovae (SN) over the redshift range 0.5 < z < 1.7, for determining cosmological distances, measuring the expansion rate of the universe as a function of time, and characterizing the nature of the so-called “dark energy” component of the universe. SN will be discovered by repeated imaging of a 7.5 square-degree area located at the north ecliptic poles. Grism spectra with resolving power λ/Δ λ = R ∼ 75 will provide broad-band spectrophotometry, redshifts, SN classification, as well as valuable time-resolved diagnostic data for understanding the SN explosion physics. This methodology features only a single mode of operation with no time-critical interactions, a single detector technology, and a single instrument. Although grism spectroscopy is slow compared to SN detection in any single broad-band filter for photometry, or to conventional slit spectra for spectral diagnostics, the multiplex advantage of being able to observe a large field-of-view simultaneously over a full octave in wavelength makes this approach highly competitive.