SeaHawk is a CubeSat designed as a proof-of-concept mission to capture high-quality, high-resolution (~100m) ocean color imagery with the low-cost miniature ocean color sensor, HawkEye. The OBPG has been supporting this mission by providing services for the collection, processing, calibration , and validation of the HawkEye data.
After the conclusion of operations for the SeaHawk mission, the OBPG assessed the state of the calibration of the Hawkeye instrument. Several issues were identified and are addressed with this reprocessing, including:
An adjustment to the prelaunch CCD flat field correction to remove a residual
cross-CCD sensor bias that was evident in the remote sensing reflectance data
was derived following the processes defined by Kwiatkowska, et al., (2008).
Over the course of the mission, the Hawkeye instrument experienced a number of detector signal reductions, which present as line drop-outs in the CCD. The cause is unknown but could be the result of small dust particles on the CCD. Most of these were able to be corrected with a detector level gain modification, though a few remain in some bands.
Given the few opportunities for Hawkeye to image the MOBY location over the mission life, the direct use of this calibration facility to provide sufficient data for a robust vicarious calibration for Hawkeye is not possible. In lieu of direct MOBY matchups for this process, the approach of Werdell et al., (2007) was employed.
Ewa J. Kwiatkowska, Bryan A. Franz, Gerhard Meister, Charles R. McClain, and Xiaoxiong Xiong, "Cross calibration of ocean-color bands from Moderate Resolution Imaging Spectroradiometer on Terra platform," Appl. Opt.47, 6796-6810 (2008)
P. Jeremy Werdell, Sean W. Bailey, Bryan A. Franz, André Morel, and Charles R. McClain, "On-orbit vicarious calibration of ocean color sensors using an ocean surface reflectance model," Appl. Opt.46, 5649-5666 (2007)
