Data Set Overview
  =================
  The LROC consists of two Narrow Angle Cameras (NACs) that provide 0.5
  meter-scale panchromatic images over a 5 km swath, a Wide Angle Camera
  (WAC) to provide images at a scale of 100 meters/pixel in seven color bands
  over a 60 km swath, (during the nominal 50 km primary mission phase) and a
  Sequence and Compressor System (SCS) supporting data acquisition for both
  cameras. LROC is a modified version of the Mars Reconnaissance Orbiters
  ConTeXt Camera (CTX) and MARs Color Imager (MARCI) provided by Malin Space
  Science Systems (MSSS) in San Diego, CA.
 
  The two NAC, WAC and SCS are located on the LRO Instrument bench, with
  their respective boresights aligned with the nadir (+Z) axis of the
  spacecraft. The SCS communicates with the LRO spacecraft over a high-speed
  SpaceWire interface, which provide both command and data communication
  pathways. LROC observations are stored on a solid state recorder (SSR)
  partition. Observations are downlinked to the ground using a Ka-band
  receiver, located at White Sands New Mexico, and processed by the MOC
  before being sent to the LROC Science Operations Center for processing
  into PDS EDR and CDR products.
 
  The calibration of a NAC EDR observation is expressed using the following
  equation [ROBINSONETAL2010]:
 
                   [Iraw(x,t,T) - m(t,T)] - [D(x,t,T) - m(t,T)] - S(x) - L(x)
  Ical(x,t,T) =    ----------------------------------------------------------
                                          F(x) * t * r
 
  Ical(x,t,T) is the calibrated signal value of pixel (x) in radiance units
  of microwatt/(cm^2*sr*nm),
  Iraw(x,t,T) is the pixel's raw signal in DN,
  t the exposure time,
  T is the temperature,
  m is the mean DN value of the masked pixels,
  D(x,t,T) is the library dark image correction array,
  S(x) is the non-linearity offset array,
  L(x) is the logistic function value for low-signal non-linearty correction
  (only if Iraw(x,t) < 400 Dn),
  F(x) is the sensitivity non-uniformity array (flat-field), and
  r is the spectral responsivity for conversion of DN into radiance units.
 
  NAC CDR generation is performed using the Intergrated Software for Imagers
  and Spectrometers (ISIS), developed by the US Geological Survey. Once
  calibration is completed, a PDS compliant CDR file is generated for
  archival purposes.
 
  The calibration of a WAC EDR observation is expressed using the following
  equation [ROBINSONETAL2010]:
 
                     Iraw(x,y,f,t,T) - D(x,y,f,t,T) + N(x,y,f)
  Ical(x,y,f,t,T) =  -----------------------------------------
                                 F(x,y,f) * t * r
 
  where Ical(x,y,f,t,T) is the calibrated signal of the pixel at position
  (x,y) in radiance units of microwatt/(cm^2*sr*nm),
  Iraw(x,y,f,t,T) is the pixel's raw signal in DN,
  f is the filter,
  t is the exposure time,
  T is the temperature,
  D(x,y,f,t,T) is the dark image,
  N(x,y,f) is non-linearity correction,
  F(x,y,f) is the sensitivity non-uniformity correction matrix (flat-field),
  and r is a filter responsivity coefficient to convert DN to radiance.
 
  WAC CDR generation is performed using the Integrated Software for Imagers
  and Spectrometers (ISIS), developed by the US Geological Survey.
 
  This data release contains portions of the LROC Calibrated Data Record
  (CDR) Archive, a collection of image data taken with the LROC instrument
  suite. A data release will contain both NAC and WAC EDR files from
  multiple days and multiple orbits.
 
  This data release also contains ancillary data files: browse and thumbnail
  version of each observation; an index file ('index.tab') that tabulates the
  contents of this data release; a cumulative index file ('cumindex.tab')
  that tabulates the entire contents of the data set; and documentation files
  describing the data products, archive volume and calibration.
 
  Processing
  ==========
  The LRO Mission Operations Center (MOC) pushes LROC science files (NAC and
  WAC observations), definitive SPICE kernels, LRO spacecraft and LROC
  instrument housekeeping and other ancillary files to the LROC SOC during
  the mission, on a daily basis. To process the NAC and WAC observations into
  PDS EDR products, the LROC SOC must ingest and process SPICE kernels and
  the housekeeping data to extract meta-data about each observation,
  including instrument temperatures and observation geometry on the lunar
  surface. Once the meta-data has been extracted and written into our
  database, the individual science files can then be processed into the
  respective EDR product.
 
  The generated LRO NAC or WAC EDR product is then ingested into ISIS using
  the lronac2isis or lrowac2isis command. Each newly ingested NAC or WAC
  image file can then be run through their respective calibration
  applications, lronaccal and lrowaccal, to generate calibrated observations
  and eventually compliant PDS CDR products.
 
  LRO NAC observations have special considerations when processing summed or
  native resolution observations during ISIS processing.
 
  LRO WAC multi-spectral and monochrome observations have special
  considerations that are addressed during ISIS processing. When WAC
  observations are ingested into ISIS, the frames are separated into ODD and
  EVEN files, based on their ordinal sequence within the original EDR file.
  This allows ISIS to unambigiously map from detector space into map space
  for a given observation. If the observation contains both VIS and UV bands,
  a separate file is created for VIS and UV, resulting in a total of four
  files for a given WAC observation: a VIS-Even file, a VIS-Odd file, a UV-
  Even file and a UV-Odd file. If only VIS or UV bands are present in the EDR
  file, only a pair of Odd/Even files is created.

Geometric Accuracy
  ==================
  Latitude and longitude coordinates calculated for the images given in the
  index.tab file were computed using the best available spacecraft position
  and orientation information at the time of processing, provide by the LRO
  Project in the form of SPK and CK kernel files. While these kernels should
  be equivalent to those retreivable from the NAIF web site
  (http://naif.jpl.nasa.gov), there may be small descrepencies and the NAIF
  versions of the kernels are preferred for all further processing.
 
  Please refer to the white paper 'A Standardized Lunar Coordinate System for
  LRO' for details on LRO project adopted lunar coordinate system, which were
  used during the calculation of latitude and longitude coordinates.