Data Set Information
DATA_SET_NAME CASSINI ORBITER CALIBRATION ISSNA/ISSWA 2 EDR VERSION 1.0
DATA_SET_ID CO_CAL_ISSNA/ISSWA_2_EDR_V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview:The Cassini Orbiter Imaging Science Subsystem (ISS) archive datasetsconsist of the Cassini ISS raw, uncalibrated experiment data recordimage files, attached and detached label files (PDS and VICAR),helpful and required PDS files, including an index table containing ahost of parameters for each image on the volumes, and ISS instrumentdocumentation. Additionally, the datasets include both pre-launchground and in-flight camera calibration images, calibration datafiles, calibration algorithms, ISS calibration processing software,sample calibrated images (using the ISS-provided calibrationsoftware), and ISS instrument calibration documentation.Several hundred thousand ISS images were taken throughout the entiremission, including Earth, Venus and Jupiter flybys, and Saturn tour.In addition to imaging these targets, ISS performed instrument groundcalibration taking images prior to launch and also while in-flight,support imaging for other Cassini instruments and optical navigationimaging; all of which are contained within these datasets.Three separate datasets are identified by the ISS team: 1)Cassini Orbiter Earth/Venus/Jupiter ISSNA/ISSWA EDRs -- Cruise phase imaging, including Earth, Venus and Jupiter flyby images. 2)Cassini Orbiter Saturn ISSNA/ISSWA EDRs -- Tour phase imaging, including Saturn, Saturn's Rings and Satellites 3)Cassini Orbiter Calibration ISSNA/ISSWA EDRs - EDR calibration-related files, including calibration data files, sample calibrated images, calibration processing software, calibration documentation and pre-launch ground calibration images. More information on the details of this volume can be found in theAAREADME.TXT file at the root level of this volume and in the DOCUMENTdirectory.Data:Image VICAR Files-----------------All ISS images are in JPL/MIPS VICAR (Video Image Communication AndRetrieval) image format. VICAR is an entire system of software,formats, and procedures for image storage and processing.Each VICAR image file is accompanied by a detached ASCII PDS labelfile. The label consists of ASCII 'keyword:value' lines describing theimportant characteristics of the image.A full explanation of VICAR, its standards, its software, andreference information can be found at website:http://www-mipl.jpl.nasa.gov/vicar/. Image Index Table-----------------The image index table file, INDEX.TAB, contains keyword informationabout each image on the volume. Some of this information comesdirectly from the EDR detached PDS image label; for example, keywordssuch as FILE_NAME, DATA_CONVERSION_TYPE, IMAGE_MID_TIME, FILTER_NAME,etc. The remaining keywords come from the Autonav software (asdiscussed above) which calculates many geometrical quantities andtarget information TARGET_DISTANCE, PIXEL_SCALE, PHASE_ANGLE,TWIST_ANGLE, etc. This file consists of fixed-length records in ASCII character format.Each line is a record containing all the keywords for a particularimage on the volume. Fields in a record are delimited by commas. Non-numeric fields are enclosed in quotes and left-justified, whereasnumeric fields are not enclosed by any characters and areright-justified. Multi-valued fields are enclosed in brackets andeach item in that field is separated by a comma.The file INDEX.LBL details the keyword name, data type, start byte,number of bytes, and format so that keywords can be easily referencedand the file can be properly read into a database.Ancillary Data:The Cassini Project produces SPICE files (spacecraft positions,planetary positions and constants, processed pointing geometry,spacecraft clock versus universal time, etc.) for use in observationplanning and in calculating many of the image keywords populating theINDEX.TAB file on this volume. These Cassini SPICE files are notincluded in this ISS data archive but can be obtained from the PDSNAIF node. However, provided to support image searching and querying, theINDEX.TAB file contains over 100 keywords related to each image,including geometrically-oriented keywords. Some of these keywordsare supplied by IO/MIPS as part of the EDR processing, others aregenerated by the ISS auto-navigation software.Other ancillary files include the collection of software interfacespecifications related to the production of the EDR data files and thearchive volume DVDs, documents related to camera calibration and thecalibration processing software, and, also, a list of publishedreferences that can provide a thorough discussion of the ISS sciencegoals and objectives and ISS camera instrument.Coordinate System:For proper interpretation of the image data, one should use aCartesian coordinate system referenced to the Earth mean equator ofJ2000. There are two ISS coordinate systems in use: that officially used onthe Cassini Project to describe camera orientation (X_cm, Y_cm),which is directly related to the readout directions of the CCDsamples and lines, and that in general use by imaging scientists,(X_im, Y_im}, to describe images which are rotated from the targetbeing imaged. There is also the spacecraft coordinate system {X_s/c,Y_s/c, Z_s/c}. The cameras, and other instruments on the RSP, arepointing in the Y_s/c direction. The positive Z_s/c axis pointstowards the spacecraft s main engines; the -Z_s/c points towards theHigh Gain Antenna; the +X_s/c axis is up. The CCD readout proceeds as follows. The bottom line of the CCD isshifted down (ie, toward the remote sensing palette, toward -X_s/c))into a vacant 1-line serial register. This line is shifted then to theleft (in the +Z_s/c direction), pixel by pixel, to the signal chainuntil the entire line is read out. The pixels are numbered by theorder in which they proceed to the signal chain. Thus, the first hassample : X_cm : 1, the last has sample : X_cm : 1024. That is, thereadout proceeds in the X_cm direction. After this line iscompletely read out, the next line is shifted down into the serialregister and read out, and so on until all 1024 lines have beenshifted into the register and then along to the signal chain. Thisresults in the following relationship between the spacecraft and thephysical ISS/CCD coordinate systems: (sample, line) : {+X_cm, +Y_cm}: {-Z_s/c, +X_s/c}. The images of celestial bodies taken by the ISS are inverted up/downand flipped left/right (ie, rotated 180 degrees) by the optics in bothcameras. The relationships between targets and inertial space, as wellas the relationship between the target and the orientation of theCassini spacecraft, are all maintained through this rotation. Thus,the image of a celestial target, as well as the `image of thespacecraft coordinate system in the focal plane, are rotated fromtheir physical orientations. A celestial target with its North polealigned with the spacecraft +X_s/c axis would appear inverted andflipped on the CCD: that is, in the focal plane and display imageplane (Fig. 26), the North pole of the target and the +X_s/c axiswould point in the direction of decreasing line (-Y_cm and -Y_im);the target s western limb (or, astronomical East) and the -Z_s/c axiswould point towards decreasing sample (-X_cm and -X_im). The CassiniC-Kernel contains information that is used by the NavigationalAncillary Information Facility (NAIF) SPICE toolkit to derive amatrix which transforms a vector in inertial coordinates into thespacecraft coordinate system (X_s/c, Y_s/c, Z_s/c). The CassiniFrames kernel describes a transformation matrix that transforms avector from the camera coordinate system (X_cm, Y_cm, Z_cm) into thespacecraft frame. The proper combination of the two describes theorientation of the physical camera/CCD system relative to inertialspace. To compute the correct orientation of inertial space, and thetargets in it, in the image plane, which is where anyone handling animage will work, one must apply an additional 180 degree rotationabout the center of the image. Software:The 'CALIBRATION' volume contains the same calibrated image and datafiles, calibration processing software files, algorithms, groundcalibration images and related calibration documentation. These filestogether will facilitate a user to process the raw ISS images tohigher-level calibrated image products. The contents of these volumeshave the inherent property that they continue to evolve and improve asthe knowledge of the mission parameters improves. As a result thesevolumes are released periodically with the latest availablecalibration files with updates described in the ERRATA.TXT file.The image processing software used to create the EDR image files iscalled VICAR (Video Image Communication And Retrieval). VICAR is anentire system of software, formats, and procedures for image storageand processing and was developed and is maintained by JPL's MIPS.A full explanation of VICAR, its standards, its software and referenceinformation can be found at website:http://www-mipl.jpl.nasa.gov/vicar/. Information on tools forvisualizing VICAR images can also be found there.Media Format:This volume is being delivered to the Planetary Data System (PDS)using DVD media. Formats are based on standards for such productsestablished by the PDS [PDSSR1992].
DATA_SET_RELEASE_DATE 2005-07-14T00:00:00.000Z
START_TIME 2003-11-09T08:44:05.709Z
STOP_TIME 2005-06-01T04:13:06.640Z
MISSION_NAME CASSINI-HUYGENS
MISSION_START_DATE 1997-10-15T12:00:00.000Z
MISSION_STOP_DATE 2017-09-15T12:00:00.000Z
TARGET_NAME
TARGET_TYPE
INSTRUMENT_HOST_ID CO
INSTRUMENT_NAME IMAGING SCIENCE SUBSYSTEM - NARROW ANGLE
IMAGING SCIENCE SUBSYSTEM - WIDE ANGLE
INSTRUMENT_ID ISSNA
ISSWA
INSTRUMENT_TYPE IMAGING SCIENCE SUBSYSTEM
NODE_NAME Imaging
ARCHIVE_STATUS ARCHIVED
CONFIDENCE_LEVEL_NOTE Confidence Level Overview:Calibration of the ISS cameras is on-going, and incomplete at thetime of this archive release. In addition to improvements in theabsolute calibration, further work needs to be done to model the darkcurrent, determine any changes in the flatfields over time, andimprove the calibration algorithms already implemented in the CISSCALsoftware package. The calibration files provided here are thereforesimply the best available at the time of archiving, and should not beconsidered final.Review:Validation is considered to have 2 aspects: 1) quality scientificsability and 2) technical compliance to PDS standards. In order tonsure PDS-compliant products, the archive volumes are validated by acollaborative effort between the ISS/CICLOPS team, the Imaging andCentral Nodes of the PDS, and non-Cassini imaging scientists. TheISS/CICLOPS team is responsible for producing PDS-compliant archivevolumes, while the PDS personnel are responsible for ensuring that thearchive volume(s) meet PDS standards. Validation is performed on eachvolume by PDS using their validation tools. ISS/CICLOPS-developedoperational volume verification tools and procedures are also utilizedprior to delivery to PDS Imaging Node. Together these verificationchecks ensure PDS-compliant archive volumes.Scientific usability is assessed through the ISS science team'snormal an routine use of the ISS data sets in their science analysis. Additionally imaging scientists not associated with the Cassiniproject participate in the archive volume peer review process wherethey verify the 'science' content of the data set, the completenessof the documentation, and the scientific validity (i.e., theintegrity and usability) of the datasets. Several reviews on sample archive volumes and directory files arebeing performed prior to the start of volume production. The peerreviews of sample volumes is conducted by PDS. These reviews serveto validate the volume for proper structure, format, completeness,and science usability. Any deficiencies in the reviewed archivevolume found are corrected and resolved. When all correctable errorshave been resolved, production of the archive volumes proceeds andfurther validation is performed on a spot check basis by the both thePDS and the ISS/CICLOPS team. Non-correctable errors (eg., an errorin the downlink data file) is described in the evolving errata file,ERRATA.TXT, included on each archive volume in the Root Directory.
CITATION_DESCRIPTION Porco, C.P., CASSINI ORBITER CALIBRATION ISSNA/ISSWA 2 EDR VERSION 1.0, CO_CAL_ISSNA/ISSWA_2_EDR_V1.0, 2005
ABSTRACT_TEXT N/A
PRODUCER_FULL_NAME CAROLYN C. PORCO
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