First Images from the Focusing Optics X-Ray Solar Imager

The Focusing Optics X-ray Solar Imager (FOXSI) sounding rocketpayload flew for the first time on 2012 November 2, producing the first focused images of the Sun above 5 keV. To enable hard X-ray(HXR) imaging spectroscopyvia direct focusing, FOXSI makes use of grazing-incidence replicated optics combined with fine-pitch solid-state detectors. On its first flight, FOXSI observed several targets that included active regions, the quiet Sun, and a GOES-class B2.7 microflare. This Letter provides an introduction to the FOXSI instrument and presents its first solar image. These data demonstrate the superiority in sensitivity and dynamic range that is achievable with a direct HXR imager with respect to previous, indirect imaging methods, and illustrate the technological readinessfor a spaceborne mission to observe HXRs from solar flaresvia direct focusing optics.