Eclipse Observations with the Airborne Coronal Emission Surveyor
The Airborne Coronal Emission Surveyor (ACES) is a new instrument using the Airborne Stabilized Platform for Infrared Experiments (ASPIRE) to explore the large-scale coronal IR emission spectrum during the 2024 total solar eclipse. ACES and ASPIRE will fly on the NSF/NCAR Gulfstream V along the path of totality during the second Great American Eclipse in 2024. ACES will use the 20 cm optical feed from ASPIRE to map emission line intensity as a function of radius and solar magnetic structure.
The program builds on the SAO team’s experience developing airborne IR instrumentation, including the Airborne Infrared Spectrometer (AIR-Spec), a cryogenic IR spectrometer that observed the 2017 and 2019 eclipses, and ASPIRE, built and ground tested during the pandemic with GV commissioning flights completed in December 2021. AIR-Spec observed a narrow range of wavelengths and imaged along only one dimension.
The PIs propose to expand their IR coronal program by surveying the entire 1–4 μm spectral range at high spectral resolution and in two spatial dimensions as a function of solar conditions and radius. ACES, the new imaging Fourier Transform Spectrometer (FTS), will search for viable lines for measuring the coronal magnetic field and plasma diagnostics at large solar radii. It will be commissioned during the April 8, 2024, North American eclipse from the NSF/NCAR GV, with a solar feed provided by ASPIRE. A GV altitude of up to 14 km will enable ACES to survey the near and mid-IR with minimal atmospheric interference. ACES is expected to observe neutral helium and 18 forbidden lines of ionized magnesium, silicon, sulfur, argon, calcium, and iron, and it may measure weaker lines of those and other ions.