Contrast limits with the Simultaneous Differential Extrasolar Planet Imager (SDI) at the VLT and MMT

We discuss contrast limits obtained during a survey of young (< 300 Myr), close (< 50 pc) stars with the Simultaneous Differential Extrasolar Planet Imager (SDI) implemented at the VLT and the MMT. SDI uses a double Wollaston prism and a quad filter to take images simultaneously at 3 wavelengths surrounding the 1.62 μm methane bandhead found in the spectrum of cool brown dwarfs and gas giants. By performing a difference of images in these filters, speckle noise from the primary can be significantly attenuated, resulting in photon ...