Title: The 2015/16 Gamma-Ray Imager/Polarimeter for Solar Flares (GRIPS) Mission Overview

Authors: N. A. Duncan, SSL/UC Berkeley, Berkeley, California, USA P. Saint-Hilaire, SSL/UC Berkeley, Berkeley, California, USA A. Y. Shih, NASA/GSFC, Greenbelt, Maryland, USA H. M. Bain, SSL/UC Berkeley, Berkeley, California, USA B. A. Maruca, SSL/UC Berkeley, Berkeley, California, USA N. A. Kelley, SSL/UC Berkeley, Berkeley, California, USA N. H. Godbole, SSL/UC Berkeley, Berkeley, California, USA P. Kaufmann, Universidade Presbiteriana Mackenzie, São Paulo, SP, BRAZIL A. Caspi, Southwest Research Institute, Boulder, CO, USA J. Sample, SSL/UC Berkeley, Berkeley, California, USA J. Hoberman, SSL/UC Berkeley, Berkeley, California, USA B. Mochizuki, SSL/UC Berkeley, Berkeley, California, USA J. Olson, SSL/UC Berkeley, Berkeley, California, USA S. E. Boggs, SSL/UC Berkeley, Berkeley, California, USA A. C. Zoglauer, SSL/UC Berkeley, Berkeley, California, USA G. J. Hurford, FHNW, Windisch, SWITZERLAND D. M. Smith, UC Santa Cruz, Santa Cruz, California, USA H. Tajima, Nagoya University, Nagoya, JAPAN M.S. Amman, LBNL, Berkeley, California, USA

Abstract : The Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument is a balloon-borne solar telescope that successfully flew during the most recent 2015/16 Antarctic summer season. During GRIPS’ 11 day mission 21 C-class flares occurred. GRIPS’ observations, in the 20 keV – 10 MeV energy range, will be used to study solar-flare particle acceleration and transport. GRIPS achieves unprecedented angular resolution (down to 12.5 arcsec FWHM) at gamma-ray energies using technological improvements such as 3D position-sensitive germanium detectors (3D-GeDs) and a single-grid modulation collimator, the Multi-Pitch Rotating Modulator (MPRM). The science instrument and gondola support systems were primarily designed, built, integrated and calibrated by UC Berkeley’s Space Sciences Lab. Here we describe the 2015/16 GRIPS mission, including the Plum Brook thermal vacuum test, Antarctic flight campaign and overall lessons learned.