Wide dynamic range photon counting ICCD for ground-based astronomy

High time resolution observations are an important subject for astrophysics, allowing investigating short time scale variations, periodic or quasi-periodic, occurring in a great variety of sources: cataclysmic variables, X-ray binaries, flare stars, pulsars, AGN. Moreover, when coupled with imaging capability, they can provide a straightforward method to identify optical counterparts of X-ray binary systems and gamma-ray sources. In this context, we are developing a Photon Counting Intensified CCD, a bidimensional detector sensitive in the optical range, with an intrinsic time resolution ranging from 16 to ∼4 ms and active area ∼3 cm2, subdivided in 2048×2048 pixels. Since for ground-based observations in the optical range the expected flux (the sky background) can be very high, we developed a highly parallel real time processing electronics, based on Field Programmable Gate Array technology, not to limit the dynamic performance of the detector. Tests on the dynamic performance of the detector are presented.