HST STIS Advanced Spectral Library Project ("ASTRAL")

ASTRAL is a Hubble Space Telescope (HST) Large Treasury Project, whose aim is to collect high-quality ultraviolet spectra of representative bright stars utilizing the high-performance Space Telescope Imaging Spectrograph. In Cycle 18 (2010–2011), ASTRAL focused on eight iconic late-type stars, devoting 146 HST orbits to the purpose. In Cycle 21 (2013–2015), the program shifted gears to the warm side of the H-R diagram, to capture 21 diverse early-type objects with an allocation of 230 orbits. The main objective is to record the targets -- including well-known bright stars like Procyon, Betelgeuse, Sirius, and Vega -- with broad uninterrupted UV coverage (1150–3100 Angstroms) at the highest signal-to-noise and highest echelle spectral resolution achievable within the alloted spacecraft time, and given a variety of observing constraints. These UV atlases have enormous interpretive value in their own right, and will complement efforts from ground-based observatories, which now routinely achieve comparably high resolution and S/N in optical and near-infrared spectra of bright stars.