Ground- and space-based UV observations with EMCCDs (Conference Presentation)

Abstract

I will present on-going detector developments in our joint NASA/CNES balloon-borne UV multi-object spectrograph, FIREBall-2, the Faint Intergalactic Redshifted Emission Balloon. FIREBall-2 is a path finding mission to test new technology (EMCCDs) and make new constraints on the temperature and density of this gas. This instrument has been designed to detect faint emission from the circumgalactic medium (CGM) around low redshift galaxies (z ~ 0.7). One major change from FIREBall-1 has been the use of a delta-doped Electron Multiplying CCD (EMCCD). EMCCDs can be used in photon-counting (PC) mode to achieve extremely low readout noise (< 1 electron). Our testing initially focused on reducing clock-induced-charge (CIC) through wave shaping and well depth optimisation with a NuVu CCD Controller for Counting Photons (CCCP). This optimisation also includes methods for reducing dark current, via cooling, and exploring substrate voltage levels. I will present some of our dark current results from laboratory testing. We recently launched FIREBall-2 from Fort Sumner, New Mexico on September 22nd, 2018. This was the first time an EMCCD has been used for UV/optical observations in flight! I will present performance data from the flight including cosmic ray rate measurements, and some of our preliminary on-sky UV results using our data reduction.

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