Deuce: A Sounding-Rocket Ultraviolet Spectrograph For Flux-Calibrated B Star Observations Across The Lyman Limit

YThe Dual-channel Extreme Ultraviolet Continuum Experiment (DEUCE) is a rocket-borne, ultraviolet spectrograph specifically designed to obtain the first flux-calibrated spectra of nearby B stars epsilon and beta Canis Majoris (CMa) across the Lyman limit at 912 angstrom. These observations will help quantify the contribution of such stars to modern ionization in the intergalactic medium. The payload operates in two channels over the 700 to 1150 angstrom extreme ultraviolet/far ultraviolet (EUV/FUV) bandpass, with resolving powers of 180 (1850) and net effective areas (including slit transmission) of 4 cm(2) (.15 cm(2)) in its large and small-slit channels, respectively. DEUCE features a large format 200 x 200 mm(2) low-noise atomic layer deposition-activated microchannel plate detector of the type baselined for the Large Ultraviolet Optical Infrared (LUVOIR) Surveyor and has demonstrated its flight performance. DEUCE has obtained the first flux-calibrated spectrum of epsilon CMa from 730 to 895 angstrom. This paper outlines the science objectives, instrument design, calibration, launches, and observations of the mission. (C) 2021 Society of PhotoOptical Instrumentation Engineers (SPIE)