Georegistration and viewport coregistration for SPEXone, the multi-angle spectropolarimeter on-board the NASA PACE satellite

In February the PACE observatory was launched. Among the instruments on board is the multi viewport spectropolatimeter SPEXone. The instrument will be used for the characterisation and quantification of aerosols in the atmosphere. For the retrieval of aerosol properties it is important to observe the degree of linear polarisation and the intensity of reflected sun light from different viewing angles. Hence the need to ensure viewports are well aligned and ground pixels observed with different viewports are correctly matched. Once the aerosol properties are determined the results need to be interpreted. For the interpretation of the results knowledge of the location on Earth is required. Therefore we match the obtained images as well with other instruments (e.g. Sentinel 5). In this presentation we explain the algorithm used to register the various images, demonstrate sub-pixel accuracy on simulated data, and finally apply the method to in flight data.