urn:nasa:pds:context:target:calibrator.gll_pct 1.0 1.7.0.0 Product_Context 2016-10-01 1.0 extracted metadata from PDS3 catalog and modified to comply with PDS4 Information Model GLL PCT Calibrator Description =========== From [CARLSONETAL1992]: The Photometric Calibration Target (PCT) and an associated optical element, the Photometric Calibration Mirror (PCM) together form a source of diffusely reflected solar radiation which can be used by the remote sensing experiments for intra- and inter-instrument comparisons. These two elements are mounted on the Science Boom; the mirror reflects solar radiation onto the diffusing target surface which is placed outboard from the mirror and in a position that can be viewed from the scan platform. In order that the target be illuminated over the nominal range of solar cone angles, the mirror is convex, with a radius of curvature of 46 cm and located 53 cm from the target. The reflecting surface is vacuum deposited aluminum, with a protective overcoat formed by its natural oxide. The target surface is similar to the Voyager diffuser plate, consisting of sand blasted aluminum. The combination produces a spectrally gray diffuse surface, with an effective albedo of roughly 0.05. They were calibrated over the spectral range of 0.3 to 5.2 micrometers and for a variety of incidence angles.