Data Set Overview
    =================

    This data set contains images acquired by Juno's Stellar Reference 
    Unit (SRU).

    This data set uses the Committee on Data Management
    and Computation (CODMAC) data level numbering system.
    The SRU EDRs are considered Level 2 or Edited Data
    (equivalent to NASA Level 0). 


    Processing
    ==========

    SRU products are produced by the program 
        make_PDS_labels_SRU_EDR.pl .
    This program converts the FITS images from
    the format internally used by the Juno SRU Team.
    This program reads an SRU image file, strips the FITS headers, extracts
    information from those headers, creates and formats the PDS labels, 
    and creates a stripped image file.


    Data
    ====

    SRU images are a standard size of 512 by 512 pixels (numbered from 0 
    through 511, inclusive). The last two rows, rows 510 and 511, 
    are 'dummy' rows, and the first two columns, columns 0 and 1, are dummy 
    columns. Thus the first pixel of real data is indexed at (row, column) 
    0, 2. When the SRU is operated using time delay integration (TDI), the 
    first row of real data (row 2) experiences an 8.1 ms exposure to the 
    optical scene (2 RPM spacecraft spin rate; see section 5.1 of the SIS).
    The SRU (instrument) frame has a boresight coordinate (255.5, 255.5).
   
    Pixel values in the EDRs are in units of output 
    analog-to-digital data number (DN). Pixel values are represented as 
    16 bit signed integers 
    with values from 0 to 16383 (2^14-1), inclusive. The SRU data only 
    occupies 14 bits, so higher order bits are always zero.
    Dummy pixels are not read out and their values are replaced with zero. 
    Any pixel with a zero value is not a valid measurement. Electronic 
    offsets cause minimum valid values to be on-zero, on the order of 550 
    or 680 DN, depending on the utilized SRU, 1 or 2 respectively.

    SRU EDR images are not compressed or processed geometrically and are 
    archived in the standard Flexible Image Transport System (FITS) format 
    (http://fits.gsfc.nasa.gov/) (Wells et al., 1981). Each image product 
    has two parts: the image itself with the extension of 'FIT' and a 
    detached label with an extension of 'LBL'. Image files include a 
    standard FITS header that is 2880 bytes long. Files are then padded 
    with zero fill (ASCII 00h) to be a multiple of 2880 bytes long, as is 
    standard for FITS files.

    Partial images are the result of one of two situations: 1.) They may 
    be commanded purposely in order to satisfy onboard command timing 
    restrictions, or 2.) Data downlink or data collection problems such as 
    outages of the Deep Space Network (DSN), spacecraft anomalies, or data 
    gaps due to weather. In either case, the EDR images are padded with 
    zeros to always be the same 512x512 pixel size. 

    Refer to the Stellar Reference Unit Standard Data Products Software 
    Interface Specification (SIS) for further details on these data products
    and corrections which can be made for camera optical distortion.

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