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:  [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 muW/(cm2*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:  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 muW/(cm2*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 coorindate system, which were used during the calculation of latitude and longitude coordinates.