The Compton telescope uses an array of twelve Germanium detectors with high spectral resolution to detect gamma rays. On its bottom half the detector is surrounded by a Bismuth germanate scintillator to shield it from atmospheric gamma rays. The telescope has an overall field of view (FOV) of 25% of the sky.
Flights
Since low-to-medium-energy gamma rays are only detectable from above the atmosphere, NCT is launched with a large 1-million m3 (35-million cu ft) Helium balloon into the stratosphere. So far NCT had two successful and one unsuccessful balloon campaigns:
On 19 May 2009, the full instrument successfully launched from Fort Sumner in New Mexico and was able to observe the Crab pulsar.[4]
Unfortunately, on 28 April 2010 a launch mishap occurred at Alice Springs, Australia, when the gondola release mechanism failed, leading to the partial destruction of the gondola.[5][6]