ULTRASPEC - An Electron Multiplication CCD camera for very low light level high speed astronomical spectrometry

We present the design, characteristics and astronomical results for ULTRASPEC, a high speed Electron Multiplication CCD (EMCCD) camera using an E2VCCD201 (1 K frame transfer device), developed to prove the performance of this new optical detector technology in astronomical spectrometry, particularly in the high speed, low light level regime. We present both modelled and real data for these detectors with particular regard to avalanche gain and clock induced charge (CIC). We present first light results from the camera as used on the EFOSC-2 instrument at the ESO 3.6 metre telescope in La Silla. We also present the design for a proposed new 4Kx2K frame transfer EMCCD.