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Update 11 Sept 2017: Alex’s papers on GRB polarization accepted to ApJ! The pair of papers “Polarimetric Analysis of the Long Duration Gamma Ray Burst GRB 160530A With the Balloon Borne Compton Spectrometer and Imager” and “Maximum Likelihood Compton Polarimetry with the Compton Spectrometer and Imager” discuss the detection of GRB160530A and a new polarization analysis technique.

Update 9 August 2017: COSI-X selected for Phase A study! An update of the COSI instrument, currently called COSI-X, was selected by NASA for a concept study. It’s one of three Explorers Missions of Opportunity chosen!


COSI is a balloon-borne soft gamma-ray (0.2-10 MeV) telescope designed to study astrophysical sources of nuclear line emission and gamma-ray polarization. Learn more by reading about the Science behind COSI, its Design and related Publications.

The COSI Team launched the instrument from Wanaka, New Zealand, in May 2016 aboard a Super Pressure Balloon.  Learn about the work in their Blog PostsTwitter FeedFacebook Wall, or in the News.