The FORCAST mid-infrared facility instrument and in-flight performance on SOFIA

Joseph D. Adams, Cornell University
Terry L. Herter, Cornell University
George E. Gull, Cornell University
Justin Schoenwald, Cornell University
Charles P. Henderson, Cornell University
Luke D. Keller, Ithaca College
James M. De Buizer, Universities Space Research Association
Gordon J. Stacey, Cornell University
Thomas Nikola, Cornell University
William Vacca, Universities Space Research Association
L. Hirsch, Cornell University
J. Wang, Cornell University
L. Andrew Helton, Universities Space Research Association

Abstract

FORCAST has completed 16 engineering and science flights as the "First Light" U. S. science instrument aboard SOFIA and will be commissioned as a SOFIA facility instrument in 2013. FORCAST offers dual channel imaging (diffraction-limited at wavelengths > 15 microns) using a 256 x 256 pixel Si:As blocked impurity band (BIB) detector at 5-28 microns and a 256 x 256 pixel Si:Sb BIB detector at 28-40 microns. FORCAST images a 3.4 arcmin x 3.2 arcmin field-of-view on SOFIA with a rectified plate scale of 0.768 arcsec/pixel. In addition to imaging capability, FORCAST offers a facility mode for grism spectroscopy that will commence during SOFIA Cycle 1. The grism suite enables spectroscopy over nearly the entire FORCAST wavelength range at low resolution (∼140-300). Optional cross-dispersers boost the spectroscopic resolution to ∼1200 at 5-8 microns and ∼800 at 9.8-13.7 microns. Here we describe the FORCAST instrument including observing modes for SOFIA Cycle 1. We also summarize in-flight results, including detector and optical performance, sensitivity performance, and calibration. © 2012 SPIE.