Exploring Where Earth's Weather Meets Space Weather

Version 6 of the new limb products is now available on the ICON FTP server and the SPDF website. A draft version of the ICON CMAD is now available on the ICON website that includes detailed descriptions of the O/N₂ products, both limb and disk.  Documentation for these products is available through http links (limb and disk) and on the ICON FTP server.

If you are unfamiliar with the Calibration, Measurement, and Algorithms Document, this provides a broad view of the calibration activites and details of the algorithms as they have been updated by the product owners and implemented in the ICON Science Data Center.

This limb product compares well to the disk product that has provided O/N2 for ICON since 2020. When compared, the two retrievals show differences that can be represented by a single offset value, as they co-vary in response to actual changes in O/N2. As with all ICON products, the scientific need is for precision and both of these products meet the mission requirements.

ICON's Extreme Ultraviolet (EUV) instrument is an “imaging spectrometer”. Its 2 dimensional detector records spectral information over the range 58.4 to 83.4 nm in the one direction, and records 12 degree wide x 1/4 degree high slices of the sky over a 16 degree field of view in the other direction.

In preparation for alignment of the toroidal grating used in the EUV instrument, an optical system has been setup to simulate the cylindrical wavefront. This simulates the instrument’s view for each slice of sky while in orbit. The optical set up consists of a convex sphere and a concave toroid that produces a line image on the EUV entrance slit to simulate what EUV will observe in space. This optics pair will be used to first align the EUV instrument using visible light, then the final alignment will take place in a vacuum chamber using EUV radiation, since EUV light is not transmitted in air.