PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = " 2013 Aug 26 - Created by J. Granahan, SAIC for the HIRES NIMS SPECTRAL IMAGE CUBESdata products." RECORD_TYPE = STREAM OBJECT = DATA_SET DATA_SET_ID = "GO-A-NIMS-4-IDACUBE-V1.0" OBJECT = DATA_SET_INFORMATION DATA_SET_NAME = " HIRES NIMS IDA SPECTRAL IMAGE CUBES" DATA_SET_COLLECTION_MEMBER_FLG = "Y" START_TIME = 1993-08-28T16:47:45 STOP_TIME = 1993-08-28T16:45:30 DATA_SET_RELEASE_DATE = 2013-07-22 DATA_OBJECT_TYPE = FITS PRODUCER_FULL_NAME = "DR. JAMES C. GRANAHAN" DETAILED_CATALOG_FLAG = "N" ABSTRACT_DESC = "This data volume contains 17 channel spectral image cubes of asteroid 243 Ida ranging from 0.7 to 5.2 micrometers in wavelength in cgs units of radiance. These data were obtained by the Galileo spacecraft Near Infrared Mapping Spectrometer on August 28, 1993. They were radiometrically calibrated using calibration measurements obtained by the Near Infrared Mapping Spectrometer during its observations of Europa on June 28, 1996." CITATION_DESC = "Granahan, J.C., HiRes Galileo NIMS Ida Spectral Image Cube GO-A-NIMS-4-IDACUBE-V1.0. NASA Planetary Data System, 2013." DATA_SET_TERSE_DESC = "Radiance spectral image cube of the spatially resolved Galileo NIMS observations of asteroid 243 Ida." DATA_SET_DESC = " Data Set Overview ================= This data volume contains a radiometrically corrected spectral image cube of the spatially resolved observations of asteroid 243 Ida as acquired by the Galileo spacecraft Near Infrared Mapping Spectrometer (NIMS) on August 28, 1993. These are products of the calibration of the raw data number files idu002tn.qub and idu004tn.qub with calibration factors contained in the file g1e003ci.qub and projected in a point perspective geometry. All of the source files are contained within the NASA pds archive of Galileo NIMS data. These spectral image cubes, ida_nims_002_scan1_radiance.fit, ida_nims_002_scan2_radiance.fit, ida_nims_002_scan3_radiance.fit, and ida_nims_004_radiance.fit, combine data acquired during the asteroid 243 Ida encounter and the Galilean Satellite encounters to produce radiometrically calibrated products. The Near-Infrared Mapping Spectrometer (NIMS) instrument is an imaging spectrometer covering the wavelength region 0.7 to 5.2 micrometers -- a region not studied by the Pioneer and Voyager spacecraft. Its spectral resolution is 0.025 micron beyond 1 micron, and 0.0125 microns below 1 micron, yielding 204 spectral elements in nominal mode. The nominal pixel size is a square 0.5 x 0.5 milliradians. The instrument acquires data in the order: (1) sampling of 17 detectors, (2) stepping of the scan mirror (20 elements in cross-cone), (3) stepping of the grating (nominally 12 steps per cycle). The nominal 204 wavelength cycle requires 4 1/3 seconds. The detectors (2 Silicon, 15 Indium Antimonide) sample approximately uniformly across the spectrum. A detailed description of the instrument may be found in [CARLSONETAL1992] and in the document directory of this data volume. The natural form of imaging spectrometer data is the spectral image cube. It is normally in band sequential format, but has a dual nature. It is a series of 'images' of the target, each in a different wavelength. It is also a set of spectra, each at a particular line and sample, over the area observed. Each spectrum describes a small portion of the area. When transformed into cubes, the data may be analyzed spatially, an image at a time, or spectrally, a spectrum at a time, or in more complex spatial-spectral fashion. The HIRES NIMS SPECTRAL IMAGE CUBE data products are spectral image cubes of the spatially resolved NIMS observations of asteroid 243 Ida. They are derived from data archived in the NASA Planetary Data Systems files idu002tn.qub and idu004tn.qub consisting of data in raw data number values stored as spectral image cubes in a band sequential integer arrays. These raw data numbers were converted into little endian floating point values using sensor sensitivity values contained in the NIMS Galilean satellite observations g1e003ci.qub archived in the NASA Planetary Data System. The HIRES NIMS SPECTRAL IMAGE CUBES pixels were rectified by creating a point perspective instrument projection and limbfitting pixels to the corresponding 243 Ida Galileo spacecraft CCD (Solid State Imager). The result are rectified band sequential radiance spectral image cubes of 243 Ida that are stored in the HIRES NIMS SPECTRAL IMAGE CUBE FITS files. Parameters ========== A band in a NIMS tube is generated for each of the 17 detectors at each grating step. (The detectors cover the range 0.7 to 5.2 microns.) The motion of the grating is determined by the commanded instrument mode: Mode Grating Grating Bands Samples/RIM steps increment Fixed Map/Spectrometer 1 0 17 182 Short Map/Spectrometer 6 4 102 26 Full Map/Spectrometer 12 2 204 14 Long Map/Spectrometer 24 1 408 7 A secondary mirror moves through twenty cross-track positions in the map modes, or is fixed near the center of its scan in the spectrometer modes. The number of lines in each image of a tube is always twenty, whether or not the mirror is moving. The number of samples is determined by the mode and the duration of the observation. (In the mosaic dataset, the image dimensions are determined by the pattern created by the motions of the secondary mirror and the scan platform.) The approximate wavelengths of the bands are determined by the mode, and by offset and start grating positions. The true wavelengths are functions of the temperature of the grating and parameters determined from the ground calibration and frequent optical flight calibrations. Known absorptions on some targets are also useful in determining these parameters. The commanded gain state is one of four sets of gains for the 14 non-thermal detectors. The three thermal detectors have two gains, automatically switching to the lower one near the mid-point of their range. Raw data values of each detector and grating step are functions of the gain state and the temperature of the focal plane assembly (FPA). Radiances are determined from raw data values using sensitivities based on the original ground calibration corrected by frequent photometric and radiometric flight calibrations. I/F values are simply radiances divided by the solar absorption at the target's distance from the sun for the wavelength in question. Further details may be found in VOLINFO.TXT in the DOCUMENT directory of the archive volume, and in the instrument paper [CARLSONETAL1992]. Processing ========== The HIRES NIMS SPECTRAL IMAGE CUBES data products are spectral image cubes of the spatially resolved NIMS observations of asteroid 243 Ida. They are derived from data archived in the NASA Planetary Data Systems files idu002tn.qub and idu004tn.qub consisting of data in raw data number values stored as spectral image cubes in a band sequential integer array. These raw data numbers were converted into little endian floating point values using sensor sensitivity values contained in the NIMS Galilean satellite observations g1e003ci.qub archived in the NASA Planetary Data System. The HIRES NIMS SPECTRAL IMAGE CUBES pixels were rectified by creating a point perspective instrument projection and limbfitting pixels to the corresponding 243 Ida Galileo spacecraft CCD (Solid State Imager) images. The results are rectified band sequential radiance spectral image cubes of 243 Ida that are stored in the HIRES NIMS SPECTRAL IMAGE CUBES FITS files. Data structure ============== The HIRES NIMS SPECTRAL IMAGE CUBES spectral image files are FITS formatted files. Each file contains three little endian floating point arrays with associated header data. The first array is a three dimensional that is a radiance spectral image cube of the asteroid 243 Ida in a band sequential format. The second array is another three dimensional array that contains the per pixel wavelength value of the pixels in the first array. The third array is a three dimensional array that contains the radiance precision of each pixel of the radiance spectral image cube. This FITS file has a detached PDS label file that describes the FITS data file structure, spacecraft mission, and the observation geometry. Ancillary Data ============== A Postscript-format Guide to the planned observations, including footprint plots on the target, instrument parameters, etc. is included in the data set, as are tables of parameters for each observation. A copy of the NIMS instrument paper [CARLSONETAL1992] is also included. Tagged Image File Format (TIFF) and Adobe Acrobat Portable Document files contain sample images and plots of the data in the HIRES NIMS SPECTRAL IMAGE CUBES can be found in the BROWSE directory. Software ======== NIMS tubes were designed to be accessed by the ISIS system, which No software is provided with the HIRES NIMS SPECTRAL IMAGE CUBES data volume. The FITS formatted file can be read with astronomical image software packages that can ingest the FITS file format. This includes IDL, a product of ITTVIS (http://www.ittvis.com) with the IDL Astronomy User's Library at NASA Goddard Space Flight Center at http://idlastro.gsfc.nasa.gov . ISIS (Integrated Software for Imagers and Spectrometers) 3.0 may also be used to ingest the FITS file for analysis and is available from the USGS via http://isis.astrogeology.usgs.gov/ ." CONFIDENCE_LEVEL_NOTE = " Confidence Level Overview ========================= The radiance and reflectance cubes in this volume have not been photometrically corrected, nor have they been corrected for thermal emission. Thus, apparent surface variations will be affected by viewing geometry and thermal properties. The radiance values contained in the HIRES NIMS SPECTRAL IMAGE CUBES data set were checked against corresponding values obtained by the Galileo Solid State Imager (SSI) multi-spectral imagery, NASA Infrared Telescope Facility spectra, and Eight Color Asteroid Survey data for asteroid 243 Ida. These were used to find the best calibration factors for the first grating step of the 243 Ida NIMS observations. Data from other grating steps were found to vary from these values. This variations in this data is thought to be caused by unplanned scan platform motions durint the NIMS 243 Ida observations. The shape of the limb of asteroid 243 Ida as observed by SSI was also used as a constraint for the position of the NIMS pixels in the data set. Each NIMS scan line was aligned with the SSI imaged asteroid limb during the time of the observation. The updated alignment was used to position the NIMS pixels in the HIRES NIMS SPECTRAL IMAGE CUBES data products. Data Coverage and Quality ========================= The HIRES NIMS SPECTRAL IMAGE CUBES data volume contains the spatially resolved NIMS observations of asteroid 243 Ida as archived as images in the NASA PDS Imaging Node. It contains data from the NIMS observations that are of a high signal to noise and that are consistent with other data sets. Lower signal to noise scans of the asteroid were omitted from this data set. Inconsistent data, those belonging to observations beyond the first grating step, were also omitted. It is thought that the 243 Ida data beyond the first grating step suffered from non-standard scan motions due to malfunctions of the Galileo Orbiter scan platform during the asteroid encounter. This resulted in archived image files with some spectral data that are not properly calibrated by coefficients obtained during the Galilean satellite encounter observations. ===========" END_OBJECT = DATA_SET_INFORMATION OBJECT = DATA_SET_MISSION MISSION_NAME = "GALILEO" END_OBJECT = DATA_SET_MISSION OBJECT = DATA_SET_TARGET TARGET_NAME = IDA END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_HOST INSTRUMENT_HOST_ID = GO INSTRUMENT_ID = NIMS END_OBJECT = DATA_SET_HOST OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "CARLSONETAL1992" END_OBJECT = DATA_SET_REFERENCE_INFORMATION END_OBJECT = DATA_SET END