DATA_SET_DESCRIPTION |
Data Set Overview : This data set contains products acquired by the JunoCam instrument. This data set uses the Committee on Data Management and Computation (CODMAC) data level numbering system. The JunoCam RDRs are considered Level 3 or Calibrated Data (equivalent to NASA Level 1A). The RDRs are corrected for instrument signature and converted to scaled radiance. Processing : JunoCam products are produced by the junomakepds.py program from the format internally used at the JunoCam Mission Operations Facility (MOF). This program reads a JunoCam image file, extracts information from its headers, formats and attaches the PDS labels, and appends the image data. The RDR is produced by inverting the onboard 12-to-8-bit companding to yield linear data numbers of detector response. A flat field correction would also be done at this step, but this is not currently implemented as the instrument response is fairly uniform without it. For planetary targets these values are then scaled such that a white surface at the solar distance at the time of imaging and with the commanded exposure time would have a pixel value of 10,000 data numbers. For images of a black sky, however, this would result in a loss of dynamic range, since most pixel values would collapse to 1 or 2 data numbers. Therefore, for such images the RDR values simply represent the number of electrons at each pixel. Since the detector's full well capacity is about 30,000 electrons of signal, this value can be represented as a 16-bit integer. Data : All JunoCam images must be a multiple of 16 pixels in both width and height. Images are broken up into subimages (also called fragments), and each fragment is transmitted separately. Raw and predictively compressed images are reconstructed by concatenating all of their image fragments and then processing; transform compressed images are processed a fragment at a time. A JunoCam data product consists of one image with decompression applied. For each image file, a header identifies various properties of the image and contains a file offset to the data portion of the image. The image data are then appended to the end of the file. Refer to the JunoCam Experiment Data Record (EDR) and Reduced Data Record (RDR) PDS Data Products Software Interface Specification (SIS) for further details on the JunoCam data products.
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