In-orbit commissioning activities results of GCOM-C/SGLI

The Japan Aerospace Exploration Agency (JAXA) is pressing forward with Global Change Observation Mission (GCOM) for long-term monitoring of earth environment. GCOM consists of two series of medium-size satellites, GCOM-W (Water) and GCOM-C (Climate). The first satellite, GCOM-W with Advance Microwave Radiometer -2 (AMSR-2), was already launched in 2012 and has been observing continuously. GCOM-C which carries the optical radiometer, Second Generation Global Imager (SGLI), was launched on December 23, 2017. SGLI observation data will produce more than 20 scientific products such as cloud, aerosol, ocean color, vegetation, ice field and so on, and will contribute to improve the understanding of the global mechanism of carbon cycle and radiation budget. SGLI includes two radiometer units of Visible and Near Infrared Radiometer (VNR) and Infrared Scanning Radiometer (IRS), which perform a wide-spectral (380 nm-12 mu m) optical observation with relatively high (250 m) spatial resolution. After the launch, the satellite and SGLI instruments were initialized and commissioned for routine operations during a three-month period called in-orbit checkout. SGLI-VNR performance tests included internal light calibration, solar diffuser calibration, dark signal calibration and electrical calibration. In addition to that, solar angle correction maneuvers were performed within L+2 weeks and lunar calibration maneuvers were performed each synodic period. 90-deg. yaw maneuvers were also performed. In this paper, the in-orbit commissioning activities of SGLI-VNR will be described. Especially we focus on the internal light calibration and solar diffuser calibration results during a commissioning phase.