The Airborne Infrared Spectrometer: Development, Characterization, and the 21 August 2017 Eclipse Observation

Abstract: On August 21, 2017, the Airborne Infrared Spectrometer (AIR-Spec) observed the total solar eclipse at an altitude of 14 km from aboard the NSF/NCAR Gulfstream V research aircraft. The instrument successfully observed the five coronal emission lines that it was designed to measure: Si X 1.431 $\mu$m, S XI 1.921 $\mu$m, Fe IX 2.853 $\mu$m, Mg VIII 3.028 $\mu$m, and Si IX 3.935 $\mu$m. Characterizing these magnetically sensitive emission lines is an important first step in designing future instruments to monitor the coronal magnetic field, which drives space weather events as well as coronal heating, structure, and dynamics. The AIR-Spec instrument includes an image stabilization system, feed telescope, grating spectrometer, and slit-jaw imager. This paper details the instrument design, optical alignment method, image processing, and data calibration approach. The eclipse observations are described and the available data are summarized.