Retrieval of spectral response functions for the hyper-spectral sensor of HISUI (Hyper-spectral Imager SUIte) by means of onboard calibration sources

HISUI (Hyper-spectral Imager SUIte), which is the next Japanese earth observation project, has been developed under the contract with Ministry of Economy, Trade and Industry(METI) and New Energy and Industrial Technology Development Organization(NEDO). HISUI is composed of hyper-spectral sensor and multi-spectral sensor. The hyper-spectral sensor is an imaging spectrometer with two separate spectral channels: one for the VNIR range from 400 to 970 nm and the other for the SWIR range from 900 to 2500 nm. Ground sampling distance is 30 m with spatial swath width of 30 km. The spectral sampling will be better than 10 nm in the VNIR and 12.5 nm in the SWIR. The multi-spectral sensor has four VNIR spectral bands with spatial resolution of 5m and swath width of 90 km. HISUI will be installed in ALOS-3 that is an earth observing satellite in the project formation phase by JAXA in FY 2015. This paper is concerned with the retrieval of spectral response functions (SRF) for the hyper-spectral sensor. The center wavelength and bandwidth of spectral response functions of hyper-spectral sensor may shift and broaden due to the distortion in the spectrometer, the optics and the detector assembly. Therefore it is necessary to measure or estimate the deviation of the wavelength and the bandwidth broadening of the SRFs. In this paper, we describe the methods of retrieval of the SRF's parameters (Gaussian functions assumed) by means of onboard calibration sources and we show some simulation's results and the usefulness of this method.