The Operational Land Imager-2: prelaunch spectral characterization

The Landsat-9 satellite will carry the Operational Land Imager-2 (OLI-2) as one of its payloads. This instrument is a clone of the Landsat-8 OLI and its mission is to continue the operational land imaging of the Landsat program. The OLI-2 will continue to populate an archive of Landsat earth images that dates back to 1972. The OLI-2 instrument is not significantly different from OLI though the instrument-level pre-launch spectral characterization process was much improved. While OLI was characterized by a double monochromator system, the OLI2 spectral characterization made use of the Goddard Laser for Absolute Measurement of Radiance (GLAMR), a system of tunable lasers that cover 350-2500nm which are fiber-coupled to a 30-in integrating sphere and is monitored by NISTtraceable radiometers. GLAMR allowed the spectral characterization of every detector of the OLI-2 focal plane in nominal imaging conditions. The in-band relative spectral responses were sampled at 1 or 2nm wavelength increments and the out-of-band responses at 10 or 20nm wavelength increments (increment is dependent on spectral band/region). The final relative spectral responses (RSRs) represent the best characterization any Landsat instrument spectral response. This paper will cover the results of the instrument-level spectral characterization, including in-band response, out-of-band response, spectral cross-talk and spectral uniformity.