Detection and imaging of the Crab Nebula with the Nuclear Compton Telescope

Abstract

The Nuclear Compton Telescope (NCT) is a balloon-borne Compton telescope designed for the study of astrophysical sources in the soft gamma-ray regime (200keV-20MeV). NCT's 10 high-purity germanium crossed-strip detectors measure the deposited energies and three-dimensional positions of gamma-ray interactions in the sensitive volume, and this information is used to restrict the initial photon to a circle on the sky using the Compton scatter technique. Thus NCT is able to perform spectroscopy, imaging, and polarization analysis on soft gamma-ray sources. NCT is one of the next generation of Compton telescopes - the so-called compact Compton telescopes (CCTs) - which can achieve effective areas comparable to the Imaging Compton Telescope's with an instrument that is a fraction of the size. The Crab Nebula was the primary target for the second flight of the NCT instrument, which occurred on 2009 May 17 and 18 in Fort Sumner, New Mexico. Analysis of 29.3 ks of data from the flight reveals an image of the Crab at a significance of 4σ. This is the first reported detection of an astrophysical source by a CCT. © 2011. The American Astronomical Society. All rights reserved.