Comparison of ICON/MIGHTI Observations with Astronomical Sky Spectra

The objective of the Michelson Interferometer for Global High-Resolution Thermospheric Imaging (MIGHTI) instrument aboard NASA’s Ionospheric Connection Explorer (ICON) satellite was to determine altitude profiles of the wind and temperature in the Earth’s upper atmosphere [1]. The winds were obtained from the Doppler shift of the measured atomic oxygen green and red line emissions at 557.7 nm and 630.0 nm [2], respectively, and the temperatures were derived from the measured molecular oxygen Atmospheric band emission [3].

Our study aims to broaden the scientific impact of the MIGHTI instrument, advance knowledge of the nightglow emissions, and improve retrievals of nighttime atomic oxygen by using the intensities of the emissions measured by MIGHTI. Accurate nighttime O-atom densities are required for modeling the chemistry and energy budget of the upper atmosphere. Just as important, a detailed understanding of the relationship between atmospheric composition and the intensity of observed nightglow emissions is essential for modeling and understanding gravity wave propagation and dissipation.

We report on our recent efforts to evaluate the absolute intensities from ICON/MIGHTI by comparing them to flux-calibrated measurements of the same emissions from sky spectra obtained by the Ultraviolet and Visual Echelle Spectrograph (UVES) of the Very Large Telescope (VLT) in Cerro Paranal, Chile.

This work is supported by the NASA GOLD-ICON Guest Investigators Program Grant 80NSSC22K0172 and the NASA Heliophysics (LNAPP) Program Grant 80NSSC23K0694.

[1] Immel et al., Space Sci. Rev. 219(41), 1-26 (2023).
[2] Englert et al., Space Sci. Rev. 219(3), 27 (2023).
[3] Stevens et al., Space Sci. Rev. 218(8), 67 (2022).