PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM SPACECRAFT_NAME = GALILEO_ORBITER INSTRUMENT_NAME = "NEAR INFRARED MAPPING SPECTROMETER" INSTRUMENT_ID = NIMS OBJECT = TEXT NOTE = "Introduction to the Galileo Near-Infrared Mapping Spectrometer (NIMS) Cube CD-ROM Set." PUBLICATION_DATE = 1999-09-10 END_OBJECT = TEXT END Contributions by: Bob Mehlman, Frank Leader Institute of Geophysics and Planetary Physics University of California Box 951567 Los Angeles, California 90095-1567 Bob Carlson, Bill Smythe, Lucas Kamp, Ashley Davies, Valerie Henderson, Tyler Brown Jet Propulsion Laboratory 4800 Oak Grove Drive Pasadena, CA 91109 Eric Eliason, Chris Isbell United States Geological Survey Branch of Astrogeology 2255 North Gemini Drive Flagstaff, Arizona 86001 January 19, 1996 Version 1.0 (Phase 0, Cruise) December 10, 1998 Version 2.0 (Phase 2, Jupiter Operations) September 10, 1999 Version 2.1 (G2 encounter) CONTENTS 1 - INTRODUCTION 2 - GALILEO MISSION 3 - NIMS INSTRUMENT 3A - PHASE 2 OPERATIONS 4 - SPECTRAL IMAGE CUBES 5 - BROWSE PRODUCTS 6A - CALIBRATION NOTES 6B - POINTING GEOMETRY NOTES 6C - DESPIKING NOTES 7 - DISK DIRECTORY STRUCTURE 8 - INDEX FILES 9 - CALIBRATION AND GEOMETRY FILES 10 - SOFTWARE 11 - LABEL KEYWORD DESCRIPTIONS 12 - WHOM TO CONTACT FOR INFORMATION 13 - ACKNOWLEDGEMENTS 14 - REFERENCES 15 - NIMS PUBLICATIONS 1 - INTRODUCTION This CD-ROM contains Spectral Image Cubes of Near Infrared Mapping Spectrometer (NIMS) observations of Jupiter and its satellites as well as browse products in image form. It is the result of systematic processing of Experiment Data Records (EDRs) acquired by the NIMS instrument during Galileo's operations at Jupiter. This document and the AAREADME.TXT file in the top level directory of this disk provide relevant information pertaining to this CD-ROM. The AAREADME.TXT file enumerates the time periods and targets included on a particular volume. 2 - GALILEO MISSION Galileo is a mission to Jupiter to perform long-term studies of the Jovian atmosphere and detailed studies of the Galilean satellites. The mission is divided into a launch/cruise phase and an orbital phase. The spacecraft trajectory required a deltaV Venus-Earth-Earth gravity assist (VEEGA). The cruise is divided into Earth-Venus (EV), Venus-Earth (VE), Earth-Earth (EE) and Earth-Jupiter segments -- with the initials used to associate observations with time. These cruise segments are further divided by spacecraft command loads, which are numbered, but not completely contiguously since some planned loads were later combined or eliminated. Important segments include VE6 (Venus encounter), EV9 and 11 (Earth 1 encounter), EE3 (Gaspra encounter), EE9 and 11 (Earth 2 encounter), EJ2 and EJ3 (Ida encounter) and EJ7 (Shoemaker-Levy 9 impact with Jupiter). Jupiter operations are divided into encounters, named for the satellite which is the principal target. The primary missions consist of the Jupiter Orbit Insertion (JOI) phase and Io encounter (I0) followed by encounters with Ganymede (G), Callisto (C) and Europa (E) designated by principal target and orbit number: G1, G2, C3, E4, E6, G7, G8, C9, C10 and E11. Data is not collected during the fifth encounter (J5) because Jupiter is behind the sun. [The Galileo Europa Mission (GEM) follows the Primary Mission. It will continue data collection in the Jupiter system, though primarily data from Europa and Io. There will be eight close encounters of Europa (E12, E14, E15, E16, E17, E18 and E19), four of Callisto (C20, C21, C22 and C23) and two of Io (I24 and I25) over a period of two years. Jupiter is behind the sun during the 13th encounter (E13).] The spacecraft is a dual-spinner, with the fundamental coordinate system in EME-1950 (Right Ascension, Declination, and Twist) and a hardware coordinate system in cone and clock. The associated spacecraft geometry is available as SPICE kernels generated by the NAIF group at JPL. The fundamental unit of the spacecraft clock is the RIM (Realtime IMaging count, 60 2/3 seconds). This is subdivided into 91 minor frames (2/3 seconds each) numbered from 0 to 90. Each minor frame is in turn subdivided into 10 RTIs (RealTime Interrupts), numbered 0 to 9. The spacecraft clock time is usually represented in the notation RIM:MF:RTI, where MF denotes the minor frame. Planned spacecraft events are described in the SSDF (Standard Sequence Data File). It is the source of several other files, including the ORPLN (ORbit PLaNning) file, the SEF (Spacecraft Event File) and the ISOE (Integrated Sequence Of Events) file. These are available through the Galileo Science Catalog. 3 - NIMS INSTRUMENT 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 Antinomide) sample approximately uniformly across the spectrum. A detailed description of the instrument may be found in [1]. Earlier descriptions may be found in references [2,3]. An electronic version of a preprint of [1] is available in the [DOCUMENT.NIMSINST] directory of this CD-ROM. The raw instrument data are organized by spacecraft clock. With a knowledge of the start and stop time of a given observation, the data can be organized into a viewable object, normally known as a qube, stacked images with spatial coordinates on the front and spectral coordinates along the "back" axis. The timing of the instrument data acquisition, with 17 detectors at a grating position sampled at (nearly) the same time, results in slightly offset geometry for each grating step. This is normally adjusted by resampling the data. First results of NIMS observations during the Galileo Venus encounter may be found in [4]. See Section 15 for a list of NIMS publications up to the time this CD-ROM volume was published. 3A - PHASE 2 OPERATIONS The failure of the Galileo High Gain Antenna (HGA) to deploy completely during cruise necessitated major changes in plans for Jupiter operations. Data return via the Low Gain Antenna (LGA) had to be maximized by careful selection and by compression where possible. To counter the vast reduction in achievable data transmission rates, new code was prepared for the random access memory of the NIMS instrument computer which allowed selection of wavelengths and mirror positions. New formats were implemented for the Command Data System (CDS) to record edited NIMS data. A NIMS playback editor was written for CDS to perform additional wavelength editing and 8-option adaptive Rice compression of NIMS data before packetizing for transmission to the ground. An optional per-detector thresholding capability was added to lower the cost of returning repetitive off-limb data. Extensive re-programming of the ground system was needed to accommodate these changes, and the EDR format had to be revised. The NIMS instrument also suffered some damage during the course of Jupiter operations, presumably radiation-induced. Detector 8, covering the 2.4-2.6 micron wavelength range, failed during the C3 encounter. Detector 3, covering the 1.0-1.26 micron range, failed during the E6 encounter. DNs acquired after these failures will appear to be extremely noisy, often (depending on the gain state) alternating between very low and very high values. Our judgment is that they are scientifically unusable. 4 - SPECTRAL IMAGE CUBES 4.1 - Data Set Overview 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. NIMS Spectral Image Cube (Mosaic) files are derived from NIMS Experiment Data Records (EDRs), which contain raw data from the Galileo Orbiter Near Infrared Mapping Spectrometer [1]. The raw EDR data have been re-arranged into band sequential form, converted to spectral radiance or I/F units based on ground and flight calibration of the NIMS instrument, and (in most cases) resampled by a complex binning procedure and projected onto the target based on the position of the spacecraft and target and the orientation of the spacecraft's scan platform. Software for generating cubes from NIMS EDRs exists in the MIPS/VICAR and ISIS systems. (The MIPS and ISIS cubes are similar in structure but somewhat different in detailed content and type of processing.) Only MIPS-generated products are included in this series of CD-ROMs. The principal systematic processing products generated by MIPS for each successful observation of a target are calibrated spectral image g-cubes (aka mosaics) and/or tubes, as appropriate. In NIMS terminology, a g-cube contains data which have been resampled and projected on the target, while a tube only has unresampled and unprojected data in NIMS instrument space -- mirror position versus time. Structurally, both are cubes. G-cubes are generated for most observations, but they are *not* generated for flight calibrations, limb scans, ring observations, sparse ride-along observations designed for other scan platform instruments, spectrometer-mode observations and any otherwise unsuitable for projection onto the target. Tubes are generated for ALL observations, even when g-cubes are made; they most accurately reflect the original unresampled data. Both g-cubes and tubes for most observations are generated in two forms for the convenience of users, with data in units of radiance, and in units of I/F. An exception is made for dark calibrations, but only for orbits from the G8 and subsequent encounters: these contain raw data numbers. All these forms contain "backplanes" of geometry and other related information. Tubes additionally have backplanes of projection co-ordinates on the target, though the datasets themselves are still in instrument space. A secondary hardcopy "mask" is also produced and serves as a "browse" product. It contains a summary 3-band RGB image (if a g-cube has been made) or footprint plot (if it has not), up to six selected spectra keyed to it, various histograms and annotation. A digital image of the mask is present on the CD-ROM in JPEG format. [An exception has been made for products from the Gaspra and Ida encounters. Since most of the asteroid data is sub-pixel in extent, and because the NIMS calibration for the asteroid encounters is not yet well understood, only raw data number (DN) tubes (and their associated masks) have been generated. It is felt that DN tubes provide a more convenient means of examining the asteroid data than the EDRs.] Calibration and geometric information used are the best available at the time of publication of these files, but they are subject to continual improvements as data analysis proceeds. Thus better g-cubes and tubes may be generated in the future. 4.2 - Parameters A band in a NIMS cube or tube is generated for each of the 17 detectors at each grating step. The motion of the grating is determined by the commanded instrument mode: Mode Grating Grating Bands steps increment Fixed Map/Spectrometer 1 0 17 Bandedge Map/Spectrometer 2 variable 34 (not used) Short Map/Spectrometer 6 4 102 Full Map/Spectrometer 12 2 204 Long Map/Spectrometer 24 1 408 The wavelengths of the bands are determined by the commanded start and offset grating positions, and by wavelength calibrations conducted on the ground and occasionally during flight. They are also weak functions of grating temperature. The pixels in a g-cube or tube of a targeted observation are in units of radiance, or in dimensionless units of I/F (radiance divided by solar emission at each wavelength). The radiances are derived from the 10-bit raw NIMS data numbers by applying band-dependent sensitivities, which are in turn products of ground and flight calibrations, of the commanded gain state and chopper mode and of the focal-plane-assembly (FPA) temperature. (During cruise, radiances were scaled by band-dependent base and multiplier values to fit into 16-bit integer words. During Jupiter operations, they are expressed as unscaled 32-bit VAX floating-point numbers. [Tubes from asteroid observations, and dark calibrations since the G8 encounter, however, contain raw data numbers -- which are in VAX 16-bit integer form.] Cube labels completely describe pixel units and formats used.) 4.3 - Data Format The g-cube and tube files follow PDS structure and labeling conventions [5,6,7]. A PDS/ISIS label begins each file, and describes all the 'objects' within using ASCII keyword=value statements. The first object is an ISIS history object [8] which describes the various steps of the generation process. The second object is a 2-D histogram of the cube. A third object (in radiance products, but not in I/F products) is a "sample spectrum qube": a 'stack' of six spectral plots, each an average over a selected area of the cube. (These also appear on the hardcopy and digital 'masks'.) The final and principal object is the actual NIMS spectral image g-cube or tube. Spectral image cube structure follows PDS and ISIS "qube" object standards [6,8]. Chapter 7 of the ISIS System Design (ISD) document [8] contains a detailed discussion of cube structure. The 'core' of the qube is a 3-dimensional array of 32-bit signed floating-point numbers, arranged in band sequential order: sample, line and band. (ISIS also supports 8-bit unsigned integers and 16-bit signed integer values. The latter form is used for raw data number tubes from many calibrations and from the asteroid encounters.) A noteworthy feature of the core is the presence of "special values" for certain pixels, representing data which is missing for one or another reason (NULL data), high and low instrument saturation, high and low representation saturation, etc. Pixels which are thresholded during playback are assigned the special value for low instrument saturation. The special values are defined in the cube label. The core is followed by a set of backplanes, or 'extra' bands, made up of 32-bit VAX floating point pixels. G-cube backplanes contain seven geometric parameters, the standard deviation of one of them, the standard deviation of a selected data band, and 0 to 10 'spectral index' bands, each a user-specified function of the data bands. (The latter might be ratios of bands, or band depths.) The geometric backplanes are latitude, longitude, incidence, emission and phase angle, slant distance and 'intercept altitude'. Tubes may have many more backplanes, since some of the geometric variables are sufficiently grating-position-dependent to require separate backplanes. Tubes generated for observations from orbit E12 on have additional grating-position-dependent geometry backplanes, for use by depatterning software being developed at the USGS/Flagstaff. (See comments in the cube label for details.) 4.4 - Cube generation Two sets of software exist to generate NIMS spectral image cubes. One is part of the ISIS (Integrated Software for Imaging Spectrometers) system; the other is part of the VICAR (Video Image Communication and Retrieval) system. Both produce similar, but not identical, NIMS cubes. The differences are in the methods of binning data into a projected space, and in the selection of geometry and other items stored in backplanes of the cubes. Both software sets provide the option of radiometrically and photometrically calibrating the individual data values. Both sets produce cubes with PDS/ISIS labels, which can be read, displayed and analyzed by generic ISIS software [8,9,10] NIMS data from the various Galileo encounters are processed into calibrated cubes, systematically by the VICAR software and selectively by the ISIS software. The systematic products, produced by the Multi-Mission Image Processing System (MIPS), are collected on CD-ROMs such as this one for distribution to the scientific community. ISIS consists primarily of programs which process, display and analyze data in cube format, data for which may come from NIMS or from other imaging spectrometers. But it is also a programming environment, in which the NIMS-specific cube generation software mentioned above was developed. It is also capable of handling data in "table" format, useful for storing spectra extracted from NIMS cubes, and in "instrument spectral library" (ISL) format, for storing laboratory spectra convolved to match the wavelength set of a particular instrument such as NIMS. ISIS was initially developed using the VMS operating system on the DEC VAX series of computers. The basic processing capabilities of the ISIS system are now available for SUN and DEC-Alpha Unix and PC Linux environments, and additional applications are currently being ported to it. VICAR is an image processing system with a long history, which has some multispectral capability, including the cube generation software mentioned above. It is currently available in both VMS and Unix versions. For additional information on ISIS and VICAR system availability and related technical support, see section 12 of this document. 5 - BROWSE PRODUCTS The 'mask' files in the BROWSE tree of this CD-ROM are digital versions of the hardcopy 'masks' generated by MIPS along with the tubes and g-cubes (mosaics). Each mask contains a summary image, half a dozen average spectra of selected areas keyed to the summary image, various histograms and annotation. Users should understand that NIMS masks are not intended as products for scientific analysis. They serve only as a guide to the spatial and spectral contents of the tube or mosaic. Browse the masks to discover which observations are of interest, then display and analyze the tubes and mosaics. (Just as a lower resolution image serves as a browse product for a higher resolution one, the NIMS mask serves as a browse product for a spectral image cube.) For g-cubes, the summary image is an RGB composite of three bands, user specified, each of which may be computed from combinations of several NIMS bands. There is also a 2-D histogram of the cube and two 1-D histograms of the summary image, before and after stretching. For tubes, the summary image is a boresight footprint with graphics superimposed showing the target body and mirror scan. There is also a 2-D histogram. The digital masks were originally produced as 3-band RGB binary image files with 8-bit pixels, 1250 lines by 1750 samples, preceded by VICAR labels. For this CD-ROM, they have been converted to JPEG format, which may be displayed with most web browsers, or generally available programs like "xv". The CD also includes thumbnail versions of just the summary images in GIF format. Each pair of files is accompanied by a detached PDS label. HTML files (starting with WELCOME.HTM in the root directory) have been included linking all masks and thumbnails together, organized by target, for ease in examining the data with a web browser. 6A - CALIBRATION NOTES (R. W. Carlson, 02feb99) Introduction For the data products from the Galileo Primary Mission, we generally are using a set of calibration parameters called the 1998A Calibration. An exception was made for the asteroid data on the G1 CD, for which the 1994A calibration is used. The earlier 1994A Calibration corrected for focal plane temperature differences between flight and laboratory calibration in a different fashion than 1998A. Spurious values in the ground calibration data files were also corrected in the newer calibration. (Also, products from dark calibration observations since the G8 encounter have contained raw data numbers (DNs), so that the calibration does not apply.) The following notes pertain to the 1998A Calibration. The 1998A Calibration was derived early in that year, and used consistently for all of the prime mission Jupiter orbital data, encompassing orbits G1 to E11. During the course of analyzing these data, we have found several errors and idiosyncracies which are currently being analyzed. They are listed below and discussed later. Known Errors and Idiosyncracies (1) The photometric calibration of Detectors 1 and 2 is uncertain, due to temporal changes in their spectral responsivities as well as in the onboard calibration target used for correction. The spectral response for these two detectors is therefore incorrect. (2) We have found that the wavelength position behavior of the instrument has changed over the orbital mission, likely due to radiation damage. (3) The dark levels for some detectors and gain states have changed with time, particularly for Detector 10 in the highest gain state, where the dark level has dropped by about 10 data numbers (DN). We used constant values for the 1998A Calibration. (4) The dark level of Detector 9 is slightly increased by the signal level of Detector 17, due to electronic crosstalk. This occurs when Channel 17 is in the low gain state. For most applications it is a small effect (a few DNs), occurring generally when viewing Jovian 5-micron hot spots. (5) Two detectors have become inoperative. Detector 8 failed during C3 and Detector 3 began producing erratic signals in E6. Calibration Corrections Methods to correct for the above-listed errors and idiosyncracies are being developed. Correction methods and parameters will be placed on the NIMS website when available (jumpy.igpp.ucla.edu/~nims/). Questions and comments are welcome and encouraged. Send them to nimsinfo@issac.jpl.nasa.gov. General Calibration Methods This CD-ROM set contains primarily radiance and I/F spectral image cubes. Calibration parameters and solar flux values used to derive these quantities are contained in each cube's labels. The following is a brief description of the methods used to arrive at this calibration and general remarks about the uncertainties. The primary source of the calibration parameters is the ground measurements of instrument sensitivities and spectral dispersion (see Carlson et al., Space Sci. Rev. 60,457, 1992). The laboratory calibration is checked and corrected using two onboard spacecraft targets: (1) the Photometric Calibration Target (PCT) with its associated relay mirror (the PCM), and (2) the Radiometric Calibration Target (RCT). The PCT/PCM system uses reflected sunlight to produce a relative standard of spectral irradiance. The spectral shape of the PCM and PCT reflectivities were measured in the laboratory but the resulting absolute radiance is not determined accurately due to illumination angle effects. As mentioned above, the spectral reflectivity (for wavelengths less than 1 micron) appears to have changed after laboratory calibration. The RCT is a black-body radiator whose physical temperature is accurately obtained using NIST-traceable resistance thermometers. Its radiance is accurately determined using the temperature measured during operation and the known emissivity. Wavelength calibration and verification uses an on-board light emitting diode and molecular bands (SO2 in Io spectra, H3+ in Jovian auroral spectra). Photometric Corrections For most of the spectral range, modifications to the ground calibration using these spacecraft targets are minor. Water vapor absorptions in the ground measurements are corrected using the spectrally-smooth reflectivity of the PCT. Small detector-dependent responsivity variations with focal plane temperature (which is lower than that used in the laboratory calibration) are established using both targets. The above are small corrections to the well-determined laboratory calibration of the InSb detectors (Detectors 3-17), which have exhibited remarkable stability. In contrast to the InSb detectors, the two Si detectors (Detectors 1 and 2, which cover the 0.7 to 1 micron range) have exhibited a decay in responsivity with time, and in a wavelength-dependent fashion. We have used the PCT/PCM spectral profile, normalized to the stable InSb detector signals, to establish the time-dependent response of the two Si detectors (apparently now stable). The PCT system's reflectivity was determined in ground calibration by two different laboratories and the results are generally consistent. However, applying these laboratory-derived reflectivities to generate the 1998A calibration values produces anomalous spectral albedos as measured by Detectors 1 and 2. A careful review leads us to conclude that the PCM/PCT reflectivities have changed. Observations of standard stars will be used to calibrate Detector 1 and 2. For the rest of the detectors (i.e. 3-17), the overall photometric accuracy - the absolute responsivity - is judged to be better than 10%, based largely on the excellent agreement between the measured spectral brightness temperatures and the independently measured physical temperatures of the RCT (<5% differences). Of more importance for spectral measurements is the relative wavelength-to-wavelength accuracy, which is estimated to be a percent or less. Spectral Calibration The spectral calibration was found in both ground and flight measurements to suffer shifts, presumably due to thermal conditions in the instrument and mechanical creep. This shift, or offset, is described by a grating rotation parameter (called PSHIFT) expressed in units of a grating step (one step corresponds to 0.0125 microns in first order). For the 1998A calibration, orbits G1 to E4, we have established that PSHIFT = -1.3. This is thought to be accurate to better than +/- 0.5, giving maximum wavelength errors of +/- 0.006 microns. The PSHIFT values for succeeding orbits are not as well established. In addition, a progressive increase with time has been found for the grating step size. This inflation of the wavelength scale has not been accounted for in the 1998A calibration. As an initial correction, developed prior to realizing the inflation effect, we employed PSHIFT = -1.0 for orbits E6 and beyond. Corrected wavelength vectors for all orbits are nearly complete and will be posted on the website, along with radiance corrections. Dark Levels Prior to applying the calibration, the dark levels of the instrument must be subtracted (the analog-to-digital converter is positively biased so optical signals can never be negative and below the digitization range). It is important to use accurate dark values, particularly at low signal levels. Ideally, the dark level should be obtained concurrently with the measurement, but this was usually not performed due to radiation noise, excessive scan platform motions, and data limitations. We have established a set of nominal dark values, which vary with detector, gain state, mirror position, and mirror direction. These have been applied to the data in producing the PDS products, but there are small, residual errors that are evident at low signal levels, producing mirror position striping and offsets between detectors, for example. Furthermore, temporal changes in the dark levels have occurred for some detectors and gain states. These will be posted. Solar Spectrum The solar spectrum used to derive I/F spectra is adopted from Allen, Astrophysical Quantities, Athlone Press, 1973, and is in good agreement with later measurements which suffer from incomplete atmospheric absorption line removal. Values are given in the cube headers. 6B - POINTING GEOMETRY NOTES (L. W. Kamp, 19jun99) Following is a general discussion of the source and accuracy of the geometry used to construct NIMS cubes and their geometric backplanes. See also references [11-15]. [For basic geometric information about each observation, consult the relevant NIMS Guide for (1) the general geometry of the encounter (orbit geometry chapter), (2) the particular geometry of the observation (pointer plot and OAPEL form) and (3) any anomalies affecting the observation (playback summary).] Source of Geometry The geometry of NIMS observations is determined by two classes of datasets: (a) scan platform pointing data and (b) data defining the relative positions of spacecraft and target body (ephemerides). The former are supplied in C-kernels, which are either "Predict" (= commanded) or generated from AACS downlink data; the latter are obtained from SP-kernels. Both sets of kernels are generated by the NAIF group and will be archived on a forthcoming CD-ROM volume of SPICE files. A priori, AACS pointing data are to be preferred over Predict pointing, since the former are actual measurements while the latter are only commanded. However, after a comparison between Predict and AACS data for the first 6 orbits, it was concluded that no significant difference exists between the accuracy of the two sets for most normal observations. Furthermore, the AACS data contain random noise on the order of 0.2 mrad (which is sometimes removed by smoothing, see below), while the Predict data, which are noise-free, are actually closer to the smoothed AACS. Therefore, in order to conserve downlink bandwidth, it was decided to rely primarily on Predict pointing for observations not in the cone pole (see below) and to transmit AACS data only for short intervals at the start and end of each observation as a check. An exception is made for observations taken through the booms (cone angles less than about 105 degrees), since there is no Predict pointing for the rotor, so cone and clock angle cannot be derived, which are required for correcting for the effects of booms. Normal Reliability Data in SP-kernels (ephemeris data) are generally highly reliable, especially after the final determination of the spacecraft trajectory. Even for cubes made before this final determination, errors due to this source are generally very small (<0.5 mrad). The only exception to this was in the asteroid encounters, where the earliest cubes required a considerable ephemeris correction. However, the final SP-kernels for those encounters appear to be very accurate. In "normal" AACS operation (inertial mode, in which both gyros and star sensor are functioning per specs), and when the cone angle is less than 150 degrees, the absolute pointing error is close to the nominal one of 1.0 mrad (standard error) in cone and clock. However, the relative error of the pointing within a given observation is considerably better than this, about 0.2 mrad. The absolute error is "reset" whenever the scan platform is moved to a new "aim point", which usually happens at the start of an observation. Inertial mode is the preferred mode for science operations. Anomalous Conditions When the cone angle is greater than 150 degrees, wobble compensation is disabled and the scan platform pointing shows an oscillation with a period equal to that of the rotor spin (18 sec) and an amplitude that varies but is at most about 1 mrad. In principle this is not an additional error source, since it is still tracked by AACS, but it degrades the NIMS data since they are no longer Nyquist-sampled, and it is possible that the relative pointing error is increased in this mode. When the gyros are turned off (cruise mode), then the relative error is considerably increased, but the absolute error remains about the same. This was the case for Ida and for some Jupiter orbits including E14. For Ida, the problem was exacerbated by the fact that the cone-control gains were improperly set at that time. Considerable effort was made by the NIMS team to improve the pointing for the highest-resolution Ida observations, but the results are still not entirely satisfactory. After orbit E11 one of the gyros started to degrade, adding an uncertainty in one dimension immediately after performing a clock or cone slew in the positive direction. The errors depend on the size of the slew. A correction was developed by AACS which gradually removes this error using the star scanner. In E14, this procedure was able to remove 10% of the error every spacecraft revolution (about 18 seconds); by E19 this fraction was increased to 40%. Occasionally, the star scanner was disabled, either for "bright-body avoidance" (E-1 encounter, Jupiter orbit G1 and possibly others) or due to an anomaly such as a guide star being incorrectly acquired (G7 orbit). In this case, the pointing error is unpredictable and can be very large. Before the "SCALPS" upload (~ March 1991), the AACS software did not have the correct calibration constants, so all pointing was subject to much larger errors. Memos on EV06/VE11 pointing will be published soon. Pointing corrections ("C-smithing") When a significant portion of the target body's limb is in the NIMS field of view, then the pointing can be corrected on the basis of our knowledge of the relative geometry, which is always much better than that of the scan platform pointing. This can reduce the error to about 0.5 NIMS FOV, or about 0.25 mrad, although it is usually somewhat greater since the limb is not always sharply distinguishable due to the shape of the NIMS response function and the scan-platform wobble. (If the limb is visible in an SSI image during the same observation, the pointing error can be determined to essentially zero error for that one point in time, but this rarely occurs in Jupiter observations.) The above technique is in theory also applicable to features other than the limb, but in practice this has not been used very often due to the difficulty of distinguishing precise spatial locations of features in NIMS images. An exception is formed by Io "hot spots", which have occasionally been used to correct pointing for Io observations. Other forms of pointing corrections include: smoothing the AACS data, which were shown to contain intrinsic noise of the order of 0.2 mrad by the analysis of the E-2 "flood mode" dataset; despiking; and fitting to an empirical model. For a given cube, the processing done on the pointing data used in its construction is reflected to a limited extent in its History object: (i) If AACS data were used, then the filename containing these data will be given as AACS_FILE_NAME. An "AACS-file" is an ascii listing of platform pointing (Euler angles, Cone angle, and Clock angle, by SCLK), which is computed from Platform and Rotor C-kernels supplied by NAIF. If Predict data were used, their source is given by the History item PLATFORM_CKERNEL_NAME. (ii) If a simple first-order correction was applied to the entire observation, which is the normal result of a fit to the limb or other features such as hotspots, then this is described by the POINTING_OFFSET item in the History. This item contains the offset in Right Ascension and Declination (in radians) that was applied to each pointing instance in the AACS-file or C-kernel used for that observation. It is important, in this context, also to note which instrument kernel ("I-kernel") was used in the generation of a given cube, since this contains another offset, the NIMS boresight offset, which has exactly the same effect as the pointing offset, and which was changed (after a systematic analysis of the results of limb fits) during the course of Jupiter operations. Most NIMS cubes used one of the following two I-kernels: NIMS_IKERNEL_MAB3.DAT (with INS-77000_BORESIGHT_XCONE_OFFSET = -0.25 mrad) NIMS_IKERNEL_MAB5.DAT (with INS-77000_BORESIGHT_XCONE_OFFSET = 0.25 mrad) (iii) For a few cubes, an I-kernel was used that contained an asymmetric offset that depends on the direction of the mirror motion, in order to correct an anomaly that turned out to be transient. This I-kernel is named NIMS_IKERNEL_MAB.DAT, and the offset between the "up" and "down" mirror scans is 0.2 mrad. In Long Map mode, this can show up as a regular apparent up/down (in Point Perspective projection, at least) motion when moving rapidly from one band to the next. (iv) If a more complicated correction was applied (which may also be applied to Predict data), this is indicated by the presence in the History of an AACS_FILE_NAME with a filetype other than ".AACS". The exact nature of the processing done is not recorded in the cube label, but the following are the more important conventions for the filetype portion of the name: a) ".MFP" means that a simple low-pass filter was applied to the AACS data in order to smooth them; b) ".IPPA" means that Predict data were used for the platform pointing (Euler angles), but cone and clock angles from the AACS data; this is equivalent to smoothing the pointing (with, generally, a small offset) and allows the correction for booms to be applied. c) ".ADPA" means that different offsets were applied to different time ranges of the AACS file; typically, this means that the observation contains several swaths across the target body, and a different offset was derived for each swath (usually by limb fits). d) ".AWP" means that a model for the rotor wobble was applied to data taken in the cone pole or in cruise mode. In general, more information on the nature of the correction applied can be found in the header of the file pointed to by the AACS_FILE_NAME item. Scan-platform pointing data used in NIMS cube generation that were obtained by processing other than simple extraction from NAIF C-kernels will be made available as NIMS-generated C-kernels in a standard PDS delivery. Names of files may differ from those to be used in a forthcoming NAIF-generated CD-ROM archive volume of Galileo SPICE files. Rules for translation of names will be published in a later volume of this series. 6C - DESPIKING NOTES (A. G. Davies, with additions by R. Mehlman, 09apr99) Introduction Within the radiation belts of the Jupiter system, data collected by the NIMS instrument often contain spikes due to charged particles impacting on the instrument's detectors. NIMS (resampled) g-cube products of the icy satellites -- Europa, Ganymede and Callisto -- have been processed to remove the worst of the radiation-induced spikes in the data. Jupiter and Io observations were *not* despiked, for reasons described below, nor were any of the (unresampled) tube products. WARNING: The despiking procedure, admittedly experimental, alters the original data. However, those data are still available in the tube products. If there is a discrepancy, for example, between the depth of an absorption band in a despiked g-cube and in the corresponding tube, the depth derived from the tube may be more reliable. (Of course the same feature may not be apparent in the tube, because its spectra aren't registered.) The Despiking Procedure Initial tube files of NIMS data were generated in solar irradiance units (I/F) . These were processed by the SPECFIX program, which identifies the worst spikes, based on certain input criteria, and removes them from the tube. The tube may then be examined to gauge the success of the despiking. SPECFIX also produces a list of the spikes, including their sample, line and band indices in the tube, original I/F values and spike sizes. A separate program, written by Lucas Kamp, translates the spike indices to Galileo spacecraft clock (SCLK) values, and converts the I/F values and spike sizes into original data numbers (DNs) and suggested replacement values, producing a spike file. These spike files are included on the same CD-ROMs which contain the NIMS EDRs, and have related filenames. When a g-cube is generated from a NIMS EDR by Lucas Kamp's (MIPS) cube generation software, the spike file is optionally used to replace original DNs thought to be spikes by their suggested replacement values, producing a despiked g-cube. The SPECFIX Program Identification of spikes was accomplished by an ISIS program developed at the USGS Astrogeology Branch, Flagstaff, AZ. SPECFIX was written by Jeff Anderson from specifications by Hugh Kieffer. It identifies and removes noise spikes from spectral image cubes. There are several steps in this process. Step one is the examination of the entire cube to locate and flag low-average spectra. Any spectrum whose mean value is less than a tolerance specified by the parameter ASETOL (average spectrum energy tolerance) is flagged with the value -2. These spectra will not be filtered or used for any statistical calculations in further steps. The next step is to filter spectra in the cube which are valid and not low-average. This is done in the following manner. A brick is convolved through the entire cube. The dimensions of the brick are specified as an input vector (DIMS) with samples and lines as odd integers between 3 and 9, and bands as an integer greater than or equal to 3; for example, 7 samples by 5 lines by 20 bands. For each brick, the average (G) of each spectrum in the brick is calculated. Using the above example, there would be up to 35 (7x5) G values, each calculated using the 20 corresponding pixels in the spectrum. Next, each spectrum is normalized using its associated average G. This procedure generates a normalized brick, which in turn is used to calculate a normalized average (H) and standard deviation (SIGMA) of each band in the brick. Again, for the above example, there would be 20 normalized averages and standard deviations. At this stage the statistics are in place to determine if there are spikes in the target spectrum. The target spectrum is typically the spectrum at the center of the brick (not true for target spectra near the edge of a cube). Each pixel (A) of the target spectrum is compared with the corresponding H and SIGMA in the following manner: DIFF = | A - G * H | TOL1 = | G * Q * SIGMA | TOL2 = P * Ptab where Q is a standard deviation tolerance. A pixel will only be replaced if it differs from the mean of the brick by more than Q * SIGMA. Q should be smaller than SQRT(samples*lines-1) and is recommended to be about 1 less than this value. P is an absolute tolerance. A pixel will be replaced only if it differs from the mean by more than P. Ptab is an optional noise spectrum. If DIFF exceeds *both* TOL1 and TOL2 the pixel A is considered a spike and will be replaced with either G * H or with a NULL special pixel value. Each time a pixel is replaced in a spectrum, the corresponding location in the SPECFIX backplane is incremented. Thus the values in the backplane will represent either a low energy spectrum (-2) or a number indicating the number of spikes found in the spectrum. If the recursive option is selected, each time a pixel is replaced in a spectrum the values for G, H, and SIGMA will be recalculated. Other parameters of SPECFIX specify the fraction of the brick (VPER) which must be valid (i.e. valid data and not low average energy) in order for filtering to occur, and the rate of movement (KDEL) in the band direction, which may be less than or equal to the band dimension of the brick. Application of SPECFIX to NIMS Data Ashley Davies of the NIMS team at JPL applied SPECFIX to NIMS tubes of observations at Europa, Ganymede and Callisto, and determined the appropriate parameters for the different NIMS targets and observations. Sample input values for Callisto and Ganymede: DIMS = (5,5,21) ASETOL = 0.01 VPER = 0.5 KDEL = 10 Q = 1.5 P = 0.01 RECURSIV = 1 Sample input values for Europa are generally the same except a Q value of 1 was used. [The despiking parameters used for a particular observation are recorded in the spike file for that observation, which accompanies its EDR on one of the NIMS EDR CD-ROMs. The parameters are in the history object, which follows the PDS label and precedes the actual list of spikes in the file.] Despiking Europa Data The low signal to noise ratio of Europa data at wavelengths greater than 2.5 microns makes it difficult for the despiking program to discriminate small spikes from non-noisy data. Therefore, the despiked products may be unreliable at these longer wavelengths. Despiking Io and Jupiter Data Data for Io and Jupiter have not yet been despiked using SPECFIX. Both of these bodies have localized hot spots with very different spectral intensities from adjacent pixels. SPECFIX has a minimum spatial resolution of 5 pixels by 5 pixels. This means that when the spectra of 25 pixels are processed and one or two of them are hot spots, the increased intensities for the hot spots are treated as spikes and removed. Investigations are proceeding into determining the best set of input parameters to remove the worst radiation spikes from Jupiter and Io data without compromising the hot spot data. Missing Detectors Due to radiation damage during the course of the Galileo Prime Mission some of the NIMS detectors have failed. For example, during orbit C3 detector 8 developed problems, the result being that data from this detector cannot be used. The observations containing data from 'bad' detectors have these data set to null. These null values are ignored by SPECFIX. SPECFIX is run on the whole data set. Comparative analyses of despiked products from whole observation datasets and sub-cubes containing segments of the dataset either side of the bad detector showed little overall difference in final product values, such differences, when they occur, affecting only the adjacent bands either side of the 'nulled' detector. 7 - DISK DIRECTORY STRUCTURE The files on this CD-ROM are organized by several top-level directories with subdirectories where appropriate. The following table shows the structure and content of these directories. In the table, directory names are followed by a designation, upper-case letters indicate an actual directory or file name, and lower-case letters indicate the general form of directory names or file names. DIRECTORY or FILENAME CONTENTS Top-level or root directory |- AAREADME.TXT Introduction to the NIMS CUBE CD-ROM. | |- AAREADME.VMS Special instructions for VMS systems. | |- ERRATA.TXT Known errata for this and earlier volumes, | liens for the future. | |- VOLDESC.CAT A description of the contents of this CD-ROM | volume in a format readable by both humans and | computers. | |- WELCOME.HTM Master HTML file for web browsers. It links to | subsidiary HTML files in the target directories | and in the DOCUMENT.HTML subdirectory. | |- WELCOME.LBL Detached label for WELCOME.HTM CATALOG This directory contains copies of PDS catalog | files (extension '.CAT') relevant to this CD-ROM. | |- CATINFO.TXT Description of files in directory. | |- MISSION.CAT A description of the Galileo Mission to Jupiter. | |- INSTHOST.CAT A description of the Galileo spacecraft and its | major components, including the orbiter and the | probe. | |- INST.CAT A description of the NIMS instrument and its | operating modes. | |- JUPMDS.CAT A description of the G-Cube (Mosaic) dataset for | targeted observations of Jupiter and its satellites. | |- JUPTDS.CAT A description of the Tube dataset for targeted | observations of Jupiter and its satellites. | |- ASTTDS.CAT A description of the Tube dataset for targeted | observations of the asteroids. (G1 CD only.) | |- SL9DS.CAT A description of the derived (table) dataset for | observations of the Shoemaker-Levy 9 comet | impact with Jupiter. (G1 CD only.) | |- REF.CAT Collected references for the above catalog files. DOCUMENT This directory contains document files | (extension '.TXT') describing products, | missions, organization, etc.. | |- DOCINFO.TXT Description of files in directory. | |- VOLINFO.TXT A detailed description of the contents and | organization of this CD-ROM volume (this file). | |- NIMSINST.TXT A brief description, with references, of the | Near Infrared Mapping Spectrometer (NIMS) | instrument. Each cube file has a label pointer | to this file. | |- SPECPROC.TXT A description of special processing performed | on EDRs containing anomalous data. Cube files | derived from such EDRs have label comments | pointing to this file. (G1 CD only, so far.) | |- HTML This directory contains miscellaneous HTML and | | GIF files subsidiary to WELCOME.HTM in the root | | directory. | | | |- BROWSEGD.HTM Guide to browse products on CD (linked from | | WELCOME.HTM) | | | |- MASKDOC.HTM Brief Guide to NIMS mask (linked from BROWSEGD.HTM) | | | |- NIMSCOOK.HTM NIMS Cookbook (guide to NIMS data files) | | (linked from BROWSEGD.HTM) | | | |- CONTACTS.HTM NIMS team contacts (linked from BROWSEGD.HTM) | | | |- NIMSLOGO.GIF NIMS logo | | | |- BLUELINE.GIF Separator | | | |- *.LBL Miscellaneous detached labels for *.HTM and *.GIF | |- eeNIMSGD Directory containing the "NIMS Guide to the 'ee' | | Orbit", where 'ee' is G1, G2, C3, E4, E6, G7, G8, | | C9, 10, 11, ... , 25. (Also, J0 refers to some | | brief calibration observations before G1, GA refers | | to the Gaspra encounter, ID to the Ida encounter and | | SL to the SL-9 encounter.) NIMS Guides for an orbit | | are on the volume containing its cube products. | | | |- GDINFO.TXT Description of files in directory. | | | |- NIMSGD.LBL PDS label describing the NIMS Guide formats. | | | | (PostScript Versions of the NIMS Guide) | | | |- NIMSGD0.PS Title Page, Foreword, Contents | | | |- NIMSGD1.PS Chapter 1: Introduction | | | |- NIMSGD2.PS Chapter 2: Orbit Overview | | | |- NIMSGD3.PS Chapter 3: Orbit Geometry | | | |- NIMSGD4.PS Chapter 4: Sequence Summary | | | |- NIMSGD5.PS Chapter 5: Detailed Observation Designs | | | |- NIMSGD6.PS Chapter 6: Wavelength Edit Tables (except Gaspra/Ida) | | | |- NIMSGD7.PS Chapter 7: Playback Summary (data actually returned) | | (Chapter 6 for Gaspra/Ida) | |- NIMSINST This directory contains a preprint of the NIMS | instrument paper. | |- INSTINFO.TXT Description of files in directory | |- INSTPUB.ASC ASCII version of the Text and Tables from the | Instrument paper. | |- INSTFGnn.PS PostScript files for Figures, nn = 01-14, from | the Instrument paper. | |- INSTPUB.LBL PDS label describing ASCII and PostScript files | mentioned above. INDEX This directory contains various index table | and index label files. | |- INDXINFO.TXT Description of files in directory. | |- BOOMCAT.TAB Boom Map index table. | |- BOOMCAT.LBL PDS label describing BOOMCAT.TAB content. | |- INDEX.TAB Cube information index table for current volume. | |- INDEX.LBL PDS label describing INDEX.TAB content. | |- CUMINDEX.TAB Cumulative cube information index table. | |- CUMINDEX.LBL PDS label describing CUMINDEX.TAB content. | |- OBSCAT.TAB Observation characteristics table for current volume. | |- OBSCAT.LBL PDS label describing OBSCAT.TAB content. | |- CUMOBSCT.TAB Cumulative observation characteristics table. | |- CUMOBSCT.LBL PDS label describing CUMOBSCT.TAB content. CALIB This directory is a placeholder for NIMS | calibration files. | |- CALINFO.TXT Information file pointing to NIMS calibration | files elsewhere. GEOMETRY This directory contains Galileo geometry files | or points to where they may be found. | |- GEOMINFO.TXT Description of files in directory, and information | about Galileo geometry files (SPICE files) elsewhere. | |- BOOMV001.NIM NIMS boom file with embedded PDS label. | |- NIMSV05.TI NIMS I-kernel with embedded PDS label. SOFTWARE This directory is a placeholder for software | for accessing cube, tube and mask files. | |- SOFTINFO.TXT Information file pointing to software, obtainable | elsewhere, for displaying NIMS cubes and masks. SL9 Directory containing derived products (in table | form) from the Shoemaker-Levy 9 impact with | Jupiter. (G1 CD only.) {target} A set of top-level directories for each target, | containing g-cubes and tubes. Target directories | may exist named JUPITER, IO, EUROPA, GANYMEDE, | CALLISTO, MISC (for ring and small satellite data) | and FLTCAL (for calibration, dark and star data). | In addition, the G1 CD contains directories named | GASPRA and IDA for tubes from the earlier asteroid | encounters. | | Cube filenames are in the form 'eetnnnab.QUB', | where 'ee' is the encounter/orbit (G1, G2... C9, | 10, 11... 25), 't' represents the target (J, I, E, | G, C, R for rings, S for small satellites, H for | heaven dark, N for calibration), 'nnn' is a file | sequence number for a particular orbit and target, | 'a' indicates the cube type (T for tube, C for | g-cube) and 'b' indicates the pixel type (R for | radiance, I for I/F, N for raw data number). These | 8.3-type names are required by ISO 9660 standards | for CD-ROM volumes; the original (longer) name of | each product may be found in each cube label (as | PRODUCT_ID) and in the cube's entry in INDEX.TAB | in the INDEX directory. | BROWSE Top-level directory for browse products (mask | files) | |- BRWSINFO.TXT Description of files in browse tree. | |- {target} Subdirectories containing browse products of | observations from particular targets, including | full NIMS masks in JPEG form, thumbprints of the | mask summary image in GIF form and detached PDS | labels describing them. | | These files have names of the form 'eetnnn.xxx' | where eetnnn is as described above for cube files | and xxx is 'JPG' for the JPEG versions of the masks, | 'GIF' for the GIF thumbnail versions of the mask | summary images and 'LBL' for the PDS label. 8 - INDEX FILES Index files are located in the INDEX directory of this disk and have file names ending with the characters ".TAB". An index file is a 'table' arranged by rows (records) and columns (fields) and provides important information about the NIMS data. Some index files are formatted to allow automatic data entry programs to access the data for entry into an existing data base system. In these tables, non-numeric fields are enclosed by double-quote characters, all fields are delimited by commas, and the last two bytes in each record are carriage-control and line-feed characters. Other table files are designed for access by ISIS cube generation software, and lack the quotes, separators and terminators. Both kinds have accompanying PDS label files whose file names end with ".LBL". Each .LBL file is a PDS Object Description Language (ODL) description of the contents of the corresponding .TAB file. ODL documentation is available in the PDS Standards Reference [6]. The following are index files found in the INDEX directory on this CD. Index Description ---------- ----------------------------------------------------- BOOMCAT.TAB Points to appropriate boom file for given time period INDEX.TAB Provides selected information about each cube (g-cube or tube) file on the volume. The table contains one row for each cube product, including tubes (unprojected data) of both radiances and I/F values for each successful observation or observation segment of the target, and G-cubes (projected data) of both radiances and I/F values for all except calibrations, limb scans and ride-along observations whose data is too sparse for efficient projection. Information about mask files can be inferred from entries for the corresponding cube. This table is the phase 2 version of the cube CD index file, for Jupiter operations. (Also for Gaspra and Ida.) OBSCAT.TAB Provides time range and status information, including wavelength and mirror position editing, about each observation for which data was received. This is the phase 2 version of the observation table, for Jupiter operations. OBSCAT0.TAB Phase 0 version of OBSCAT.TAB, describing observations from the Gaspra, Ida and Shoemaker-Levy 9 encounters. It has fewer parameters than the phase 2 table. (G1 CD) (CALCAT.TAB and DRKCAT.TAB tables, summarizing NIMS dark and calibration files, will be added in later CDs when the files themselves are included.) The following tables provide detailed descriptions of the contents of the index files. This includes the starting and ending byte positions of each field in each table. These byte positions specify the actual fields and do not include the double-quote marks and commas that may separate the fields. Table 1 - BOOMCAT.TAB -------------------------------------- Byte Positions Description ---------------------------------------------------------------------- 2 - 9 NATIVE_START_TIME_RIM : The spacecraft start clock count that indicates the starting period when the Boom Obscuration file is to be used. 16 - 23 NATIVE_STOP_TIME_RIM : The spacecraft stop clock count that indicates the ending period when the Boom Obscuration file is to be used. 30 - 36 BOOM_VOLUME_ID : The CD_ROM volume containing the Boom Obscuration files referenced in the table. BOOM_VOLUME_ID = "GO_1104" for all files on this CD-ROM. 40 - 59 BOOM_FILE_NAME : The name of the boom obscuration file to use for a NIMS data set for the indicated time periods (start and stop native time). BOOM_FILE_NAME = "[GEOMETRY]BOOMV001.NIM" for all files on this CD-ROM. Table 2 - INDEX.TAB -------------------------------------------------- Byte Positions Description --------------------------------------------------------------------------- 2 - 8 CUBE_VOLUME_ID : The CD_ROM volume containing the g-cube or tube file for the observation or observation segment. 12 - 21 CUBE_DIRECTORY_NAME: The CD_ROM directory for the g-cube or tube file, e.g. [JUPITER] or [IO]. The mask file will be found in a subdirectory of the same name under the [BROWSE] root directory. The directory specification is in VMS format; i.e. enclosed in square brackets. 25 - 36 CUBE_FILE_NAME : The CD name of the g-cube (or tube) file. Both radiance and I/F tube files will exist for all observations except for certain calibration files and pre-Jupiter asteroid observations, for which only raw DN tubes are present. Radiance and I/F g-cube files will exist for most observations, not including limb scans, ridealong and dark observations, flight calibrations and asteroid data. Tube files will have names of the form 'eetnnnTx.QUB' where 'eetnnn' usually corresponds to the EDR name, and x is R for radiance, I for I/F or N for raw data number. (The EDR names are made up of the encounter ee, the target t and a sequence number nnn, e.g. G1J001.EDR.) Similarly, g-cube files will have names of the form 'eetnnnCx.QUB'. Names of special products may have sequence numbers that do not correspond to those of the EDR they were made from. The original MIPS product names can be found in the index file (INDEX.TAB) and in individual product labels as the value of PRODUCT_ID. 40 - 46 MASK_VOLUME_ID : The CD_ROM volume containing the mask file which is the browse product for the g-cube or tube. (This field is distinct from CUBE_VOLUME_ID so that either g-cube /tube or mask alone can be updated on subsequent volumes.) The name of the mask file can usually be constructed from the first six characters of CUBE_FILE_NAME by appending the extension .JPG. 50 - 70 MISSION_PHASE_NAME : The mission phase during which data was acquired. Phase names are assigned by the Galileo project. 74 - 89 TARGET_NAME : The (primary) target of the observation or observation segment. 93 - 117 DATA_SET_ID : A unique alphanumeric identifier for the entire data set, constructed according to PDS conventions. 121 - 135 SPACECRAFT_NAME : The name of the spacecraft which hosts the instrument referenced in the INSTRUMENT_ID object. 139 - 142 INSTRUMENT_ID : An abbreviated name or acronym which identifies the instrument that took the data. 146 - 156 NATIVE_START_TIME : The spacecraft clock count (rrrrrrrr.mm) at which data acquisition for the g-cube or tube began. 160 - 170 NATIVE_STOP_TIME : The spacecraft clock count (rrrrrrrr.mm) at which data acquisition for the cube or tube ended. 174 - 193 START_TIME : The Universal Time Coordinated (UTC, in ISO format) at which data acquisition for the cube or tube began. 197 - 216 STOP_TIME : The Universal Time Coordinated (UTC, in ISO format) at which data acquisition for the cube or tube ended. 220 - 231 OBSERVATION_NAME: The name assigned to the observation during the Galileo planning process. 235 - 258 PRODUCT_ID: A unique name for the g-cube or tube included on this CD-ROM, which distinguishes it from other products generated from the same data by MIPS. The (8.3 format) CD-ROM name may be found in the CUBE_FILE_NAME column. 262 - 271 PRODUCT_CREATION_TIME : The Universal Time Coordinated (UTC) at which the NIMS product was generated. 274 - 279 MINIMUM_LATITUDE : The minimum latitude of data included in the cube or tube. 281 - 286 MAXIMUM_LATITUDE : The maximum latitude of data included in the cube or tube. 288 - 294 EASTERNMOST_LONGITUDE : The easternmost longitude of data included in the cube or tube. Range: 0-360. 296 - 302 WESTERNMOST_LONGITUDE : The westernmost longitude of data included in the cube or tube. Range: 0-360. 304 - 309 INCIDENCE_ANGLE : The incidence angle at the approximate center of the spatial area covered by the g-cube or tube. 311 - 316 EMISSION_ANGLE : The emission angle at the approximate center of the spatial area covered by the g-cube or tube. 318 - 323 PHASE_ANGLE : The phase angle at the approximate center of the spatial area covered by the g-cube or tube. 325 - 325 GAIN_MODE_ID : There are 4 NIMS gain states, which determine the gains applied individually to the 14 non-thermal detectors. Gain state 2 is designed for observing a bright Jupiter in each detector. Gain state 3 and 4 are each more sensitive by factors of two and four, respectively. Gain state 1 is similar to gain state 2, except channels 10-14 are each reduced in order to obtain measurements of the Radiometric Calibration Target. 328 - 352 INSTRUMENT_MODE_ID : The principal NIMS instrument modes are LONG, FULL, SHORT and FIXED MAP and the corresponding SPECTROMETER modes. A LONG grating cycle of 24 steps results in 17*24 or 408 wavelengths or bands in a cube. A FULL grating cycle of 12 steps results in 204 bands. A SHORT grating cycle of 6 steps results in 102 bands. A FIXED grating results in only 17 bands. In MAP modes, the secondary mirror traverses 20 cross-cone positions. In SPECTROMETER modes, it is stationary, but samples are taken with the same frequency as in MAP modes. 355 - 359 LINE_SAMPLES : The number of data instances along the horizontal axis of each band of the g-cube or tube. 361 - 365 LINES : The number of data instances along the vertical axis of each band of the g-cube or tube. 367 - 371 BANDS : The number of spectral bands (or wavelengths) in the g-cube or tube. 373 - 376 WAVELENGTH_SET_ID : An integer assigned to each unique set of returned wavelengths, with the same instrument mode, start grating position and offset grating position. 379 - 394 SECONDARY_TARGET_NAME : The secondary target of the observation, if any; otherwise N/A. 397 - 404 MAP_SCALE : The ratio of the actual distance between two points on the surface of the target body to the distance between the corresponding points on the map; i.e. in the data product. It is expressed in units of kilometers per pixel. It is related to the map resolution and the radius of the target body by the relation: 1 degree = (2*radius*pi)/360 kilometers. 406 - 413 MAP_RESOLUTION : The map resolution is related to the map scale and the radius of the target body. It is expressed in units of pixels per degree. See above description of map scale. 416 - 436 MAP_PROJECTION_TYPE : The type of projection characteristic of a given map (data product); e.g. MERCATOR or ORTHOGRAPHIC or POINT_PERSPECTIVE. 439 - 447 SLANT_DISTANCE : The distance from the spacecraft to a measured point on the target body at the center of the instrument field of view. The value is the average of the minimum and maximum values of slant distance in the observation. 449 - 457 CENTRAL_BODY_DISTANCE : The distance from the spacecraft to the center of the primary target of the planetary system. For Galileo and its satellites, this is the distance to the center of Jupiter. The value is the average of the minimum and maximum values of central body distance in the observation. 459 - 464 SUB_SPACECRAFT_LATITUDE : The latitude of the subspacecraft point, the point which lies directly below the spacecraft. The value is the average of the values at the beginning and end of the observation. 466 - 472 SUB_SPACECRAFT_LONGITUDE : The longitude of the subspacecraft point, the point which lies directly below the spacecraft. The value is the average of the values at the beginning and end of the observation. 474 - 479 SUB_SOLAR_LATITUDE : The latitude of the subsolar point, the point on a body's reference surface where a line from the body center to the sun intersects the surface. The value is the average of the values at the beginning and end of the observation. 481 - 487 SUB_SOLAR_LONGITUDE : The longitude of the subsolar point, the point on a body's reference surface where a line from the body center to the sun intersects the surface. The value is the average of the values at the beginning and end of the observation. Table 3 - OBSCAT.TAB -------------------------------------- 1 - 12 OAPEL_NAME : The Orbital Activity Profile ELement ID identifies a single planned observation. It is popularly known as the OAPEL name. 13 - 24 ALIAS_NAME : The Alias Name identifies the original name of another instrument's observation when NIMS is riding along (receiving data) for that observation. 25 - 25 OAPEL_EXTENSION : Identifies a part of an observation which has been separated for processing convenience. A, B, C... are used for playback segments; R, S, T... for realtime segments. The extension may be blank for a single unsplit playback observation, but must be R for an unsplit realtime observation. 26 - 27 PARAMETER_SET_ID : An identifier used in the uplink process. 28 - 40 NATIVE_START_TIME : The spacecraft clock count at the beginning of the observation segment. It is in the form RIM:MF:RTI where RIM is 8 characters, MF (minor frame) is 2 characters (0-90) and RTI (real time interrupt) is a single character (0-9). 41 - 53 NATIVE_STOP_TIME : The spacecraft clock count at the end of the observation segment. 54 - 54 PARTITION : The partition of the spacecraft clock; i.e. it begins at 1 and increments by 1 each time the clock is restarted. 55 - 63 SPARE : Reserved bytes. 64 - 71 TARGET_NAME : The primary target of the observation. Besides the various planets and satellites, this may be SKY (for dark calibrations), STAR (for boresight calibrations) or CAL (for optical and radiometric calibrations). 72 - 73 INSTRUMENT_MODE_ID : A number (0-15) which identifies the NIMS instrument mode during the observation segment: 0 Safe (fixed spectrometer) 1 Full map 2 Full spectrometer 3 Long map 4 Long spectrometer 5 Short map 6 Short spectrometer 7 Fixed map 8 Bandedge map 9 Bandedge spectrometer 10 Stop and slide map 11 Stop and slide spectrometer 12-15 Special sequences (programmable) (Modes 10-15 are not used during phase 2.) 74 - 74 GAIN_STATE_ID : Number (1-4) identifying the NIMS gain state, which governs the gains of the non-thermal detectors 1-14. Gain state 3 gains are about twice those of gain state 2. Gain state 4 gains are about twice those of gain state 3. Gain state 1 gains for detectors 1-10 are about the same as those for gain state 2, but differ for detectors 11-14. The thermal detectors (15-17) are automatically dual-gain and are not affected by the gain state. 75 - 75 CHOPPER_MODE_ID : Number (1-4) identifying the NIMS chopper mode. These are 1: reference mode, 2: 63 hertz mode, 3: free run, 4: off. 63 hertz mode was used for the two Earth/Moon encounters and the Gaspra encounter. Reference mode was used for the Venus and Ida encounters, and will be used for all Jupiter encounters. 76 - 76 OFFSET_GRATING_POSITION : Number (0-7) identifying the initial offset of the NIMS grating. This is a physical grating position. Logical grating positions are measured from this point. The default (and most common) value is 4. 77 - 100 NIMS_PARAMETER_TABLES : Contents of the NIMS Parameter Tables (PTABs), A and B, which control operation of the NIMS instrument. See the NIMS instrument paper for details. Each PTAB is represented here as 6 2-digit numbers. Columns 77 - 88 for PTAB A; 89 - 100 for PTAB B. Within each PTAB: 1 - 2 MODE_REPEAT_COUNT : Number of times the PTAB will be re-used before control is switched to the *other* PTAB. 3 - 4 MIRROR_OPERATION_FLAG : A non-zero value indicates the secondary mirror is moving (map mode); a zero value indicates that it is fixed at a position in the middle of the mirror scan (spectrometer mode). 5 - 6 AUTOBIAS_FLAG : A non-zero value indicates the autobias mechanism is off; a zero value indicates it is in use. The autobias is turned off only when the NIMS instrument is at room temperature, during testing. The flag is normally NOT set, implying that the thermal detectors (15-17) have different gains in each half of the DN range. 7 - 8 START_GRATING_POSITION : When added to the OFFSET_ GRATING_POSITION, this item determines the physical grating position at which the grating cycle begins. It is usually zero, but sometimes 1 in full grating modes, or 1-3 in short grating modes. 9 - 10 GRATING_INCREMENT : The increment in physical grating position between grating steps. It is 1 in long grating modes, 2 in full grating modes and 4 in short grating modes. It is 0 in fixed grating modes. 11 - 12 GRATING_POSITIONS : Number of actual grating steps in a grating cycle. It is 24 for long grating modes, 12 for full and fixed grating modes and 6 for short grating modes. (Full and fixed modes are distinguished by the GRATING_INCREMENT.) 101 - 101 ELECTRONIC_CALIBRATION_FLAG : A '1' indicates that an electronic calibration was commanded during the first RIM of the observation; a '0' indicates it was not. 102 - 102 OPTICAL_CALIBRATION_FLAG : A '1' indicates that an optical calibration was commanded during the first RIM of the observation; a '0' indicates it was not. 103 - 103 REAL_TIME_FLAG : A '1' indicates that the observation was returned in real time; a '0' indicates it was not. 104 - 104 RECORD_FLAG : A '1' indicates that the observation was recorded and played back later; a '0' indicates it was not. 105 - 105 THRESHOLDING_FLAG : A non-zero value (1-3) indicates that the recorded observation was thresholded during playback. The per-detector threshold values selected are included later in this table. A zero indicates no thresholding was done. 106 - 106 SPARE : Spare byte. 107 - 111 RTI_SELECT_DOWN_MASK : Ones (select) or zeros (deselect) for each of the 5 RTIs (Real Time Interrupts) during a downscan of the NIMS mirror. Four mirror positions are traversed during each RTI. 112 - 116 RTI_SELECT_UP_MASK : Ones (select) or zeros (deselect) for each of the 5 RTIs (Real Time Interrupts) during an upscan of the NIMS mirror. Four mirror positions are traversed during each RTI. 117 - 117 SPARE : Spare byte. 118 - 118 COMPRESSION_FLAG : Flag governing compression of recorded NIMS data by CDS before transmission to the ground. A 0 indicates no compression. A 1 indicates Rice compression with reference values saved for each detector before each mirror scan. 119 - 119 SPARE : Spare byte. 120 - 122 ESTIMATED_COMPRESSION : Estimated Rice compression ratio (0.0 to 9.9) for the observation. 123 - 125 EST_COMPRESSION_ERROR : Estimated error in Rice compression ratio for the observation. 126 - 130 RATE_CONTROL_LOWER_LIMIT : Lower limit (in 16-bit words per RIM) of the Rate Control option. The number of mirror positions played back is increased if this limit is reached. Zero if rate control not selected. 131 - 135 RATE_CONTROL_UPPER_LIMIT : Upper limit (in 16-bit words per RIM) of the Rate Control option. The number of mirror positions played back is reduced if this limit is reached. Zero if rate control not selected. 136 - 152 SPARE : Spare bytes. 153 - 155 WAVELENGTHS : Number of wavelengths selected (1-408) for this observation. 156 - 158 TELEMETRY_FORMAT_ID : Telemetry format: playback modes are MPW, LPU and LNR; realtime transmission is represented by RT. 159 - 179 UTC_START_TIME : Expected start time of observation in UTC. Non-ISO format is yyyy-ddd/hh:mm:ss.mmm. 180 - 200 UTC_STOP_TIME : Expected stop time of observation in UTC. Non-ISO format is yyyy-ddd/hh:mm:ss.mmm. 201 - 267 SPARE : Spare bytes. 268 - 318 THRESHOLD : Per-detector threshold values used for playback of this observation. DNs which are less than these values are not returned. A zero value indicates no thresholding for that detector. 319 - 328 WET_GROUP_ID : A 10-digit ID for Wavelength Edit Table selection group. Format is mmeelllnnn where mm is instrument mode (0-15), ee is number of entries in group, lll is number of wavelengths and nnn is a sequence number. 329 - 330 WET_GROUP_ENTRIES : Number of entries in Wavelength Edit Table selection group. 331 - 512 WET_GROUP : Wavelength Edit Table group, consisting of as many as 26 entries. Each entry consists of a count and a detector mask. As the NIMS instrument executes a grating cycle, these detector masks govern wavelength selection, each applied the specified number of times. Each entry consists of 2 items in 7 columns: 1 - 2 WET_ENTRY_COUNT : Number of consecutive grating steps associated detector mask is applicable. 3 - 7 DETECTOR_MASK : Hexadecimal representation of 17-bit detector mask, in form BHHHH, where B is 0 or 1 and H has range 0-F in hexadecimal. Each of the 17 1's and 0's represent selection (1) or absence (0) of a detector while this WET group entry is active. Detector 1 is represented by the first (left hand) bit. Table 4 - OBSCAT0.TAB -------------------------------------- 1 - 12 OAPEL_ID : The Orbital Activity Profile ELement ID identifies a single planned observation. It is popularly known as the OAPEL name. 14 - 14 SEGMENT_ID : The segment ID identifies a part of an observation which has been separated for processing convenience. (Parts of observations in different instrument modes are usually processed separately.) Ordered segments within an observation are usually represented by alphabetic characters in order, beginning with 'A'. 16 - 17 PARAMETER_SET_ID : The parameter set ID (PSID) is a brief alias for the OAPEL_ID arising in the sequence generation process. It is usually 2 characters in length and unique within an encounter. 19 - 29 NATIVE_START_TIME : The spacecraft clock count that indicates the beginning of the observation segment. 31 - 41 NATIVE_STOP_TIME : The spacecraft clock count that indicates the end of the observation segment. 43 - 44 INSTRUMENT_MODE_NUMBER : A number (0-15) which identifies the NIMS instrument mode during the observation segment: 0 Safe (fixed spectrometer) 1 Full map 2 Full spectrometer 3 Long map 4 Long spectrometer 5 Short map 6 Short spectrometer 7 Fixed map 8 Bandedge map 9 Bandedge spectrometer 10 Stop and slide map 11 Stop and slide spectrometer 12-15 Special sequences (programmable) 47 - 47 GAIN_MODE_NUMBER : A number which identifies the gain state (1-4) of the NIMS instrument during the observation segment. These states vary roughly from low gain (1) to high gain (4) and apply to the non-thermal detectors (1-14) only. 50 - 50 CHOPPER_MODE_NUMBER : A number which identifies the chopper mode of the NIMS instrument during the observation segment: 1 Reference mode 2 63-hertz mode 3 Free-run 4 Off 53 - 53 GRATING_OFFSET : The physical offset (0-7) of the NIMS grating during the observation segment. It defines the physical grating position of logical grating position 0. 54 - 89 The contents of the two Parameter Tables (PTABs) in the NIMS instrument. The PTABs control the operation of the instrument. Six items have been extracted from each 4-byte parameter table. 54 - 71 PTAB A 54 - 56 MODE_REPEAT_COUNT : The mode repeat count is the number of times the grating cycle defined in the PTAB is to be repeated before control is transferred to the other PTAB. It is the first byte of the PTAB. 59 MIRROR_OPERATION_FLAG : The mirror operation flag, if set, indicates that the NIMS secondary mirror is operating, i.e. the instrument is in a MAP mode. If the flag is not set, the mirror remains in position 9 (of 0-19), i.e. the instrument is in a SPECTROMETER mode. The flag is the first bit of the second byte of the PTAB. 62 AUTOBIAS_FLAG : The autobias flag, if set, means that thermal channel autobias is off. This is intended for use only when the NIMS instrument is at room temperature. The flag is normally NOT set, implying that the thermal detectors (15-17) have different gains in each half of the DN range. This flag is the second bit of the second byte of the PTAB. 64 - 65 START_GRATING_POSITION : The start grating position is the first logical position of the grating when the PTAB assumes control of the instrument. It is in the 6 least significant bits of the second byte of of the PTAB. 67 - 68 GRATING_POSITION_INCREMENT : The grating position increment controls the step size between grating positions. It is the third byte of the PTAB. 70 - 71 GRATING_POSITIONS : The number of grating positions (separated by the grating position increment) in one repetition of the operation defined in the PTAB, except for fixed map and safe modes, in which it governs only the motions of the secondary mirror. It is the fourth byte of the PTAB. 72 - 89 PTAB B (see PTAB A above for description and relative location of fields) 92 - 92 ELECTRONICS_CALIBRATION_FLAG : An electronic calibration of the NIMS instrument will occur in the first RIM of the observation if the flag is set. 94 - 94 OPTICAL_CALIBRATION_FLAG : An optical calibration of the NIMS instrument will occur in the first RIM of the observation if the flag is set. 96 - 114 START_TIME : The start time of the observation as a Universal Time in ISO format, corresponding to NATIVE_START_TIME. 115 - 115 REALTIME_FLAG : If the flag is set, the observation was transmitted in the realtime data stream. 117 - 117 RECORD_FLAG : If the flag is set, the observation was recorded on the Galileo tape recorder and transmitted later. 120 - 127 PRIMARY_TARGET_NAME : The primary target of the observation. Besides the various planets and satellites, this may be SKY, STAR (for boresight calibration), DARK (for dark calibrations) or CAL (for optical and radiometric calibrations). 9 - CALIBRATION AND GEOMETRY FILES 9.1 - Calibration and Dark Files Calibration and dark files are not included on this cube CD-ROM. They are required for processing NIMS EDRs into cubes and tubes, and must currently be obtained from the NIMS team. They will be included on later volumes in this set, or on a special volume. Dark files exist for each NIMS gain state and contain average dark values as functions of detector, mirror position and mirror direction. They are derived from "heaven dark" or other special observations at different times in the various encounters, or from off-limb data taken during some observations. Dark values must be subtracted from raw NIMS data numbers before conversion to radiance units. Calibration files contain NIMS instrument sensitivities and other instrument parameters required for the conversion of dark-subtracted NIMS data numbers to radiance units. The sensitivities are derived from ground calibration data and corrected periodically from data acquired in flight calibration sequences throughout the mission. 9.2 - Geometry Files Kay Edwards' map of Galileo boom obscurations as a function of scan platform cone and clock angles is used to remove boom interference from NIMS products. It has an embedded PDS label, and is in the GEOMETRY directory of each cube CD. The SPICE I kernel describes NIMS instrument geometry. It has an embedded PDS label, and is in the GEOMETRY directory of each cube CD. SPICE S, P and C kernels describe spacecraft, planet and scan platform geometry, respectively. They are available from the Galileo Science Data Team. A limited number of SPICE files are delivered with the ISIS system. The SPICE files used in generating NIMS cubes will be included on later volumes in this series, or on a special volume. 10 - SOFTWARE No specific cube access software is provided with this version of the NIMS Cube CD-ROMs. ISIS (Integrated Software for Imagers and Spectrometers) is the best available software package for display and analysis of NIMS cubes (g-cubes and tubes.) It is available in Unix (including Linux) and VMS versions. (See section 12.) The ENVI system, developed under IDL, is also designed for accessing data in cube format, and is available in Unix versions from Research Systems Inc (RSI). Simple multi-platform software for examining cubes is under development by PDS. This software is known as NASAview; currently available versions will display images from a cube. A version under development will also display spectra. (See the PDS web site at http://stardust.jpl.nasa.gov.) Many generic image display systems can be used to display individual bands in a cube file. One must first calculate the offset (in bytes) to the image to be displayed. Find the ^QUBE statement in the label, and use its value (v) to determine the starting byte of the first band of the cube: (v-1)*512 + 1. That is, skip (v-1)*512 bytes. Then use the CORE_ITEMS = (samples, lines, bands) statement to find the dimensions of the core, and CORE_ITEM_BYTES to get the size of each pixel (usually 4 for cubes from Jupiter observations, and 2 for cubes from cruise encounters). To display the first band, offset (v-1)*512 bytes and display a samples by lines image of 16- or 32-bit pixels. To display an arbitrary band, say band b, change the offset to (v-1)*512 + (b-1)*samples*lines*pixel_size. One other thing, the cubes on this CD were generated on VAX hardware. (CORE_ITEM_TYPE has the value VAX_INTEGER or VAX_REAL.) On most non-DEC Unix workstations, or just about anything but a VAX or DEC Alpha, bytes in VAX_INTEGER pixels will have to be swapped, and VAX_REAL pixels will have to be converted to IEEE, before display. Backplanes always contain 4-byte VAX_REAL pixels, and may be displayed by offsetting the entire core and any preceding backplanes and converting the pixels from VAX to IEEE floating point. (Conversion utilities to do all this exist in the ISIS system.) The masks (browse products) on this CD-ROM are in JPEG and GIF format and may be displayed by most web browsers, and by commonly available display software such as 'xv'. 11 - LABEL KEYWORD DESCRIPTIONS Keyword Descriptions for attached labels of NIMS g-cube and tube files, and detached labels of mask files. Explanations are either interspersed with the label statements, or placed on the right hand side of individual statements after an exclamation point. Remarks between /* and */ delimiters are actual in-label comments. The label values are sometimes shown as 'xxx...' if important variables; others are typical numbers. Note: this label is fictitious, some statements may be incompatible in reality. 11.1 - G-Cube/Tube Labels (attached) [The sample is a g-cube label. Where tube labels differ, the differences are described in the explanations.] CCSD3ZF0000100000001NJPL3IF0PDS200000001 = SFDU_LABEL This keyword provides a mechanism for files on this CDROM to conform to the SFDU (Standard Formatted Data Unit) convention. The first 20 bytes identify the file as a CCSDS SFDU entity. The next 20 bytes identify the file as a registered product of the JPL SFDU control authority. The components of both SFDU labels are the control authority identifier (characters 1-4), the version identifier (character 5), the class identifier (character 6), a spare field (characters 7-8), a format identifier (characters 9-12), and a length field indicator (characters 13-20). The version identifier indicates a "Version-3" label, which allows files to be delimited by an end-of-file marker, rather than requiring a byte count to be embedded in the label. The keyword conforms to standard PDS keyword syntax and the value associated with this keyword will always be SFDU_LABEL. RECORD_TYPE = FIXED_LENGTH This keyword defines the record structure of the file. The NIMS EDR files are always fixed-length record files. This keyword always contains the value FIXED_LENGTH. RECORD_BYTES = 512 Record length in bytes for fixed length records, always 512 for ISIS cubes. FILE_RECORDS = xxxx Total number of records contained in the file. LABEL_RECORDS = xx Number of records in the label area of the image file. FILE_STATE = CLEAN An ISIS keyword which distinguishes CLEAN (good) files from DIRTY (incomplete) files. All files on this CD should be CLEAN. CHECKSUM = xxxxxxxxxx CHECKSUM_NOTE = "Unsigned 32-bit sum of all bytes after label records" The sum of all the bytes after the label. This can be used to verify the reading of a cube or tube file. ^HISTORY = xx OBJECT = HISTORY END_OBJECT = HISTORY The (^) character prefixing a keyword indicates that the keyword is a pointer to the starting record of a data object in the file. In this case, the keyword is the pointer to the History Object. The number of records found in an object is determined by differencing the value of the pointer keyword from the value of the next pointer or to the end of the file. There are no label statements describing the history object. It contains the ISIS history of processes which led up to the creation of this data file. It can be read by the ISIS LHLIST program, or by simply TYPEing the file, as long as you stop before you get to the next object. ^HISTOGRAM_IMAGE = xxx OBJECT = HISTOGRAM_IMAGE /* Two dim histogram image structure */ LINES = 256 LINE_SAMPLES = xxx SAMPLE_TYPE = UNSIGNED_INTEGER SAMPLE_BITS = 8 SAMPLE_NAME = BAND LINE_NAME = INTENSITY NOTE = "This is an unannotated two-dimensional histogram 'image' showing frequency of measured 'Intensity' versus band number. The 'Intensity' may be DN, Radiance, or BDRF (Bi-Directional Reflectance), or a combination of BDRF with Radiance, with BDRF below a cutoff band number and radiance above. The cutoff is defined by: BDRF_RAD_TRANSITION_BAND_NUMBER. The 'Intensity' is DN only if CORE_NAME in the QUBE object is RAW_DATA_NUMBER." BDRF_RAD_TRANSITION_BAND_NUMBER = 1 END_OBJECT = HISTOGRAM_IMAGE These statements describe the 2-d histogram object, which is an 'image' of the number of pixels in 256 radiance bins in each band (up to 408). The samples are unsigned byte values, 0-255. The ISIS program HISTPIC can be used to display it as an image. ^SAMPLE_SPECTRUM_QUBE = xxx OBJECT = SAMPLE_SPECTRUM_QUBE /* Sample spectrum non-standard qube structure */ AXES = 3 AXIS_NAME = (SAMPLE,LINE,REGION) ITEMS = (500,340,6) ITEM_BITS = 4 ITEM_TYPE = UNSIGNED_INTEGER REGION_UPPER_LEFT_LATITUDE = (0.000,30.000,60.000,90.000,85.000, 75.000) REGION_UPPER_LEFT_LONGITUDE = (260.000,260.000,270.000,300.000, 0.000,30.000) REGION_SAMPLES = (5,5,5,5,5,5) REGION_LINES = (5,5,5,5,5,5) NOTE = "Each band is a partially annotated 'image' of a spectral plot over a selected region in the NIMS data cube. The plot is of DN, radiance or BDRF (Bi-Directional Reflectance) versus NIMS_band or wavelength. Nibble pixels may assume 3 values, representing background (usually 0), spectrum (usually 15), and an intermediate (gray) value used to display standard deviation over region. Radiance and I/F may coexist in each plot, with I/F below a cutoff wavelength and radiance above. The cutoff is defined by: BDRF_RAD_TRANSITION_WAVELENGTH." BDRF_RAD_TRANSITION_WAVELENGTH = 3.71111 END_OBJECT = SAMPLE_SPECTRUM_QUBE These statements describe a strange object which reproduces the six average spectra appearing on the hardcopy 'mask'. It is a 'qube' consisting of a stack of six 'images', each of which is a spectral plot. The various REGION_ keywords describe the origin and size of the areas over which the spectra are averaged. The ISIS program SPECPIC can be used to display it. ^QUBE = xxxx OBJECT = QUBE A pointer to, and the beginning of the description of, the principal object of this file: a Spectral Image Cube. The standard PDS object name for this structure is 'QUBE'. The QL3 program in VMS ISIS, the CV program in Unix ISIS, the IDL ENVI system, and the PDS NASAview program (under development) can be used to display the bands and spectra of the cube interactively. /* Qube structure: Standard ISIS Cube of NIMS Data */ AXES = 3 AXIS_NAME = (SAMPLE,LINE,BAND) A cube has 3 axes. ISIS software for Standard ISIS cubes requires that the axes be named SAMPLE, LINE and BAND. /* Core description */ CORE_ITEMS = (xxx,yyy,zzz) ! samples, lines, bands CORE_ITEM_BYTES = 4 ! or 2 for DNs or scaled radiances CORE_ITEM_TYPE = VAX_REAL ! VAX_INTEGER for DNs or CORE_BASE = 0.0 ! scaled radiances CORE_MULTIPLIER = 1.0 /* Core scaling is: True_value = base + (multiplier * stored_value) */ CORE_VALID_MINIMUM = 16#FFEFFFFF# CORE_NULL = 16#FFFFFFFF# CORE_LOW_REPR_SATURATION = 16#FFFEFFFF# CORE_LOW_INSTR_SATURATION = 16#FFFDFFFF# CORE_HIGH_INSTR_SATURATION = 16#FFFCFFFF# CORE_HIGH_REPR_SATURATION = 16#FFFBFFFF# CORE_BELOW_THRESHOLD = -32762 CORE_MISSING_SENSITIVITY = -32754 CORE_NAME = SPECTRAL_RADIANCE ! or RADIANCE_FACTOR (I/F) ! = Radiance/(PI*Solar_Flux) ! or RAW_DATA_NUMBER (DNs) CORE_UNIT = 'uWATT*CM**-2*SR**-1*uM**-1' ! or DIMENSIONLESS for ! RADIANCE_FACTOR or raw DNs /* Core units: to convert these radiances to SI units (W/m^2/sr/uM), */ /* the data in the cube must be divided by 100. */ These statements describe the structure of the 'core' of the cube, which contains the individual bands in each of the NIMS wavelengths. The various CORE_xxxxxx statements describe special values which identify invalid pixels and various kinds of saturation. CORE_NAME and CORE_UNIT describe the scientific content of the pixels. SPATIAL_BINNING_TYPE = FOOTPRINT_AVERAGE THRESHOLD_WEIGHT = 0.00000 FOOTPRINT_GRID_SIZE = 10 /* SPATIAL_BINNING_TYPE, FOOTPRINT_GRID_SIZE, THRESHOLD_WEIGHT, and */ /* (for certain projections) MAXIMUM_PIXEL_DISTORTION, are parameters */ /* that are not relevant to the Tube core data, but can be used in */ /* subsequent ISIS processing to generate a projected cube from a */ /* tube file with program NIMSGEOMF. Note that the value: */ /* SPATIAL_BINNING_TYPE = FOOTPRINT_AVERAGE */ /* does trigger the addition of two extra backplanes per grating */ /* position: the RIGHT_EDGE_PROJ_LINE/SAMPLE backplanes. */ EXPANDED_RADIUS = xxxx.xx DARK_UPDATE_TYPE = NOUPDAT FILL_BOX_SIZE = 0 FILL_MIN_VALID_PIXELS = 0 PHOTOMETRIC_CORRECTION_TYPE = NONE These statements describe the parameters of the spatial binning procedure used to generate the cube. /* Suffix description */ SUFFIX_BYTES = 4 SUFFIX_ITEMS = (0,0,11) BAND_SUFFIX_NAME = (LATITUDE,LONGITUDE,INCIDENCE_ANGLE, EMISSION_ANGLE,PHASE_ANGLE,SLANT_DISTANCE,INTERCEPT_ALTITUDE, PHASE_ANGLE_STD_DEV,SPECTRAL_RADIANCE_STD_DEV,'B22/B1', 'B26*2/(B24/2+B28)') BAND_SUFFIX_UNIT = (DEGREE,DEGREE,DEGREE,DEGREE,DEGREE,KILOMETER, KILOMETER,DEGREE,'uWATT*CM**-2*SR**-1*uM**-1',UNKNOWN,UNKNOWN) BAND_SUFFIX_ITEM_BYTES = (4,4,4,4,4,4,4,4,4,4,4) BAND_SUFFIX_ITEM_TYPE = (VAX_REAL,VAX_REAL,VAX_REAL,VAX_REAL, VAX_REAL,VAX_REAL,VAX_REAL,VAX_REAL,VAX_REAL,VAX_REAL,VAX_REAL) BAND_SUFFIX_BASE = (0.000000,0.000000,0.000000,0.000000,0.000000, 0.000000,0.000000,0.000000,0.000000,0.000000,0.000000) BAND_SUFFIX_MULTIPLIER = (1.000000,1.000000,1.000000,1.000000, 1.000000,1.000000,1.000000,1.000000,1.000000,1.000000,1.000000) BAND_SUFFIX_VALID_MINIMUM = (16#FFEFFFFF#,16#FFEFFFFF#,16#FFEFFFFF#, 16#FFEFFFFF#,16#FFEFFFFF#,16#FFEFFFFF#,16#FFEFFFFF#,16#FFEFFFFF#, 16#FFEFFFFF#,16#FFEFFFFF#,16#FFEFFFFF#) BAND_SUFFIX_NULL = (16#FFFFFFFF#,16#FFFFFFFF#,16#FFFFFFFF#,16#FFFFFFFF#, 16#FFFFFFFF#,16#FFFFFFFF#,16#FFFFFFFF#,16#FFFFFFFF#,16#FFFFFFFF#, 16#FFFFFFFF#,16#FFFFFFFF#) BAND_SUFFIX_LOW_REPR_SAT = (16#FFFEFFFF#,16#FFFEFFFF#,16#FFFEFFFF#, 16#FFFEFFFF#,16#FFFEFFFF#,16#FFFEFFFF#,16#FFFEFFFF#,16#FFFEFFFF#, 16#FFFEFFFF#,16#FFFEFFFF#,16#FFFEFFFF#) BAND_SUFFIX_LOW_INSTR_SAT = (16#FFFDFFFF#,16#FFFDFFFF#,16#FFFDFFFF#, 16#FFFDFFFF#,16#FFFDFFFF#,16#FFFDFFFF#,16#FFFDFFFF#,16#FFFDFFFF#, 16#FFFDFFFF#,16#FFFDFFFF#,16#FFFDFFFF#) BAND_SUFFIX_HIGH_INSTR_SAT = (16#FFFCFFFF#,16#FFFCFFFF#,16#FFFCFFFF#, 16#FFFCFFFF#,16#FFFCFFFF#,16#FFFCFFFF#,16#FFFCFFFF#,16#FFFCFFFF#, 16#FFFCFFFF#,16#FFFCFFFF#,16#FFFCFFFF#) BAND_SUFFIX_HIGH_REPR_SAT = (16#FFFBFFFF#,16#FFFBFFFF#,16#FFFBFFFF#, 16#FFFBFFFF#,16#FFFBFFFF#,16#FFFBFFFF#,16#FFFBFFFF#,16#FFFBFFFF#, 16#FFFBFFFF#,16#FFFBFFFF#,16#FFFBFFFF#) /* The backplanes contain 7 geometric parameters, the standard deviation */ /* of one of them, the standard deviation of a selected data band, */ /* and 0 to 10 'spectral index' bands, each a user-specified function of the */ /* data bands. (See the BAND SUFFIX NAME values.) */ /* Longitude ranges from 0 to 360 degrees, with positive direction */ /* specified by POSITIVE LONGITUDE DIRECTION in the IMAGE MAP PROJECTION */ /* group. Latitudes are planetocentric. */ /* INTERCEPT ALTITUDE contains values for the DIFFERENCE between */ /* the length of the normal from the center of the target body to the */ /* line of sight AND the radius of the target body. On-target points */ /* have zero values. Points beyond the maximum expanded radius have */ /* null values. This plane thus also serves as a set of "off-limb" */ /* flags. It is meaningful only for the ORTHOGRAPHIC and */ /* POINT PERSPECTIVE projections; otherwise all values are zero. */ /* The geometric standard deviation backplane contains the standard */ /* deviation of the geometry backplane indicated in its NAME, except */ /* that the special value 16#FFF9FFFF replaces the standard deviation */ /* where the corresponding core pixels have been "filled". */ /* The data band standard deviation plane is computed for the NIMS data */ /* band specified by STD DEV SELECTED BAND NUMBER. This may be either */ /* a raw data number, or spectral radiance, whichever is indicated by */ /* CORE NAME. */" [In a tube, there are a larger number of backplanes, as described in the following comments extracted from a tube label...] /* The backplanes contain 12 geometric parameters for each grating position */ /* (latitude, longitude, line, sample, right-edge-of-NIMS-FOV line, right-edge*/ /* sample), 3 Euler angles [RA,Dec,Twist], 3 components of the 'RS-vector' */ /* from Target-body center to Spacecraft), 5 'global' geometric parameters */ /* which apply to all grating */ /* positions, the time (in 'chops', see below) of the first grating position, */ /* and 0 to 10 'spectral index' bands, each a user-specified function of the */ /* data bands. (See the BAND SUFFIX NAME values.) */ /* Longitude ranges from 0 to 360 degrees, with positive direction */ /* specified by POSITIVE LONGITUDE DIRECTION in the IMAGE MAP PROJECTION */ /* group. */ /* INTERCEPT ALTITUDE contains values for the DIFFERENCE between */ /* the length of the normal from the center of the target body to the */ /* line of sight AND the radius of the target body. On-target points */ /* have zero values. Points beyond the maximum expanded radius have */ /* null values. This plane thus also serves as a set of "off-limb" */ /* flags. It is meaningful only for the ORTHOGRAPHIC and */ /* POINT PERSPECTIVE projections; otherwise all values are zero. */ /* The NATIVE TIME band of the suffix is the time in "chops" of */ /* the first grating position at the corresponding line and sample */ /* after the NATIVE START TIME, where 63 chops = 1 second. */ [End tube comments] STD_DEV_SELECTED_BAND_NUMBER = 10 STD_DEV_SELECTED_BACKPLANE = 5 The above statements describe the individual backplanes of the cube in much the same way the previous statements describe the core. SUFFIX_ITEMS shows that there are no line or sample suffixes on the core, only band suffixes, which we call backplanes. The comments pretty well explain it all. /* Data description: general */ DATA_SET_ID = 'GO-x-NIMS-4-MOSAIC-V1.0' The PDS defined data set identifier for NIMS cubes, tubes & masks at target x. V = Venus, E = Earth, L = Moon, A = Asteroid, J = Jupiter, JS = Jupiter satellites, JR = Jupiter rings. SPACECRAFT_NAME = GALILEO_ORBITER MISSION_PHASE_NAME = GANYMEDE_1_ENCOUNTER INSTRUMENT_NAME = 'NEAR INFRARED MAPPING SPECTROMETER' INSTRUMENT_ID = NIMS ^INSTRUMENT_DESCRIPTION = "NIMSINST.TXT" The file pointed to is in the DOCUMENT directory, and gives a brief description of the NIMS instrument. TARGET_NAME = IO START_TIME = 1996-06-28T03:11:02Z ! UTC STOP_TIME = 1996-06-28T03:11:59Z NATIVE_START_TIME = "3498838.00.0" ! Galileo spacecraft clock count NATIVE_STOP_TIME = "3498838.86" OBSERVATION_NAME = 'G1INCHEMIS01A' NOTE = "Dayside observation of Io // // MIPL Systematic Processing Product" PRODUCT_ID = "G1INCHEMIS01A_MSY04.QUB" This uniquely identifies the particular cube generated from this data. MSY stands for MIPS Systematic (processing). PRODUCT_CREATION_DATE = 1998-04-23 SPECIAL_PROCESSING_TYPE = 1 /* The EDR from which this product was made required special */ /* processing by the NIMS team due to anomalous behavior of */ /* the NIMS instrument in the Jupiter radiation field during */ /* part of the G1 encounter. There may be some loss of data */ /* quality. See [DOCUMENT]SPECPROC.TXT on CD for details. */ The above statement and comment may only be found in certain G1 products. IMAGE_ID = NULL ! or (image_id_1, image_id_2 ...) These values would identify SSI images taken of the same target, at or near the same time as the NIMS data. INCIDENCE_ANGLE = 51.52 EMISSION_ANGLE = 14.74 PHASE_ANGLE = 66.22 SUB_SOLAR_AZIMUTH = 175.87 SUB_SPACECRAFT_AZIMUTH = 3.34 Various average geometric parameters of the observation, near the center of the spatial area covered. START_SUB_SPACECRAFT_LATITUDE = 65.61 START_SUB_SPACECRAFT_LONGITUDE = 296.45 STOP_SUB_SPACECRAFT_LATITUDE = 55.77 STOP_SUB_SPACECRAFT_LONGITUDE = 321.48 START_SUB_SOLAR_LATITUDE = -1.80 START_SUB_SOLAR_LONGITUDE = 148.85 STOP_SUB_SOLAR_LATITUDE = -1.80 STOP_SUB_SOLAR_LONGITUDE = 148.98 Various geometric parameters, at the beginning and at the end of the observation. MINIMUM_SLANT_DISTANCE = 110287.00 MAXIMUM_SLANT_DISTANCE = 112998.00 MIN_SPACECRAFT_SOLAR_DISTANCE = 7.78387e+08 MAX_SPACECRAFT_SOLAR_DISTANCE = 7.78388e+08 MINIMUM_CENTRAL_BODY_DISTANCE = 796379.00 MAXIMUM_CENTRAL_BODY_DISTANCE = 796472.00 Various geometric parameters, as ranges throughout the observation. POINTING_OFFSET = (-0.000340,-0.000480) SCAN_RATE_TOLERANCE = 0.230769 MEAN_SCAN_RATE = 0.878685 /* The unit of SCAN RATE TOLERANCE is mrad/s. */ /* The unit of MEAN SCAN RATE is the Nyquist scanning rate, which depends on */ /* the instrument mode: it is one-half FOV (0.5 mrad) per grating cycle. */ The above items relate to the operation of Galileo's scan platform. /* Data description: instrument status */ INSTRUMENT_MODE_ID = LONG_MAP ! or FULL_,SHORT_,FIXED_MAP,... See section 4 (SPECTRAL IMAGE CUBES) for details about the various modes. GAIN_MODE_ID = 2 ! 1-4 CHOPPER_MODE_ID = REFERENCE ! or 63_HERTZ START_GRATING_POSITION = 00 OFFSET_GRATING_POSITION = 04 GRATING_POSITION_INCREMENT = 02 GRATING_POSITIONS = 12 Instrument modes, etc. (see instrument paper for details) MEAN_FOCAL_PLANE_TEMPERATURE = 66.10 MEAN_RAD_SHIELD_TEMPERATURE = 119.70 MEAN_TELESCOPE_TEMPERATURE = 134.60 MEAN_GRATING_TEMPERATURE = 139.90 MEAN_CHOPPER_TEMPERATURE = 138.90 MEAN_ELECTRONICS_TEMPERATURE = 288.50 Instrument temperatures at the approximate time of the observation. For Jupiter observations, usually only FPA and grating temperatures are available in the label; the others are shown as zero though nearby values may be found in temperature tables on the EDR CD-ROMs. MEAN_DARK_DATA_NUMBER = (27.00,27.03,27.21,27.11,26.72,25.72, 24.39,25.04,26.00,24.87,27.96,29.02,27.99,28.24,29.05,27.31, 26.78) /* The "mean dark data numbers" are the DN value of dark sky for each of the */ /* 17 NIMS detectors, averaged over the mirror-position-specific values used */ /* in the computation of radiance. The original dark values were obtained */ /* from either off-limb portions of the observation or special "heaven dark" */ /* observations for an encounter. */ GROUP = BAND_BIN ! Vectors have been shortened... /* Spectral axis description */ BAND_BIN_CENTER = (0.6951,0.7080,0.7210,0.7340,0.7470,0.7600, ! Wavelength 0.7730,0.7860,0.7990,0.8120,0.8250,0.8380,0.8340,0.8470, ... ) BAND_BIN_UNIT = MICROMETER BAND_BIN_ORIGINAL_BAND = (1,2,3,4,5,6,7,8,9,10,11,12,13,14, 15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33, ... ) BAND_BIN_GRATING_POSITION = (0,1,2,3,4,5,6,7,8,9,10,11,0,1, 2,3,4,5,6,7,8,9,10,11,0,1,2,3,4,5,6,7,8,9,10,11,0,1,2,3, ... ) BAND_BIN_DETECTOR = (1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2, 2,2,2,2,2,3,3,3,3,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4, ... ) BAND_BIN_SOLAR_FLUX = (155030.0000,149411.0000,143996.0000, 138776.0000,133747.0000,129391.0000,125319.0000,121374.0000, ... ) BAND_BIN_SENSITIVITY = (0.1838,0.2188,0.2521,0.2837,0.3145, 0.3211,0.3093,0.3036,0.3191,0.3283,0.3121,0.2788,0.3007, ... ) /* "Band Bin Sensitivity" is the Sensitivity for each band, in units of */ /* DN/radiance_unit (see CORE UNIT). These values are functions of */ /* reported focal plane assembly temperature during the observation and */ /* of ground and flight calibration data. They may be used to construct */ /* "idealized data numbers" (DNs which would have been measured by an */ /* anomaly-free instrument) by the formula: */ /* DN = dark_value + sensitivity * radiance, */ /* where 'dark_value' is approximated by the MEAN_DARK_DATA_NUMBER array. */ /* Note that actually measured raw DNs are not obtainable in this way, */ /* due to corrections for instrument anomalies (see the referenced */ /* INSTRUMENT_DESCRIPTION for details) and possible resampling of the */ /* data. */ END_GROUP = BAND_BIN The above group of statements describe the band dimension of the cube in vector form, giving individual values for each band. BAND_BIN_CENTER is the wavelength. BAND_BIN_ORIGINAL_BAND is an ISIS construct, which preserves the original band number after a subcube is selected. For Jupiter operations, it also reflects any wavelength editing done on the spacecraft, showing only the original band numbers of the remaining bands. BAND_BIN_GRATING_POSITION & _DETECTOR specify the NIMS grating position & detector for each particular wavelength. BAND_BIN_SOLAR flux measures the solar flux in each band at the appropriate distance from the sun. BAND_BIN_SENSITIVITY is described by the label comment above. If scaled radiance, BAND_BIN_OFFSET & _MULTIPLIER will describe the scaling into 16-bit integers, on a per-band basis. GROUP = IMAGE_MAP_PROJECTION /* Projection description */ MAP_PROJECTION_TYPE = POINT_PERSPECTIVE MAP_SCALE = 27.561 MAP_RESOLUTION = 1.100 SUB_SPACECRAFT_LATITUDE = 61.24 SUB_SPACECRAFT_LONGITUDE = 310.87 LINE_SUB_SPACECRAFT_OFFSET = 74.58 SAMPLE_SUB_SPACECRAFT_OFFSET = 72.69 TARGET_CENTER_DISTANCE = 111983.0 LINE_OPTICAL_AXIS_OFFSET = 87.75 SAMPLE_OPTICAL_AXIS_OFFSET = 8.17 FOCAL_LENGTH = 800.0 FOCAL_PLANE_SCALE = 5.000 OFFSET_DIRECTION = TO_ORIGIN MINIMUM_LATITUDE = -30.79 MAXIMUM_LATITUDE = 87.83 MINIMUM_LONGITUDE = 224.31 MAXIMUM_LONGITUDE = 358.85 EASTERNMOST_LONGITUDE = 224.31 WESTERNMOST_LONGITUDE = 358.85 COORDINATE_SYSTEM_TYPE = "BODY-FIXED ROTATING" COORDINATE_SYSTEM_NAME = PLANETOCENTRIC POSITIVE_LONGITUDE_DIRECTION = WEST A_AXIS_RADIUS = 1737.40 B_AXIS_RADIUS = 1737.40 C_AXIS_RADIUS = 1737.40 MAP_PROJECTION_ROTATION = 50.06 SAMPLE_FIRST_PIXEL = 1 SAMPLE_LAST_PIXEL = 113 LINE_FIRST_PIXEL = 1 LINE_LAST_PIXEL = 150 END_GROUP = IMAGE_MAP_PROJECTION The final group of statements describe the projection used to create the cube, or, if this is the label of an (unprojected) tube, the projection used to create backplanes of projection co-ordinates. A detailed description of the keywords may be found in the PDS Standards Reference, Appendix A.20 [6]. END_OBJECT = QUBE This marks the end of the QUBE object description. END This marks the end of the keywords for the label area. Bytes in the label area after the END statement are ignored. 11.2 - Mask Label (detached) [This label describes the JPEG mask and GIF thumbnail, and how they are linked by HTML on the CD-ROM.] PDS_VERSION_ID = PDS3 ! Later version of PDS RECORD_TYPE = UNDEFINED ! Standards than cube label DATA_SET_ID = "GO-J-NIMS-4-MOSAIC-V1.0" SPACECRAFT_NAME = GALILEO_ORBITER MISSION_PHASE_NAME = GANYMEDE_1_ENCOUNTER TARGET_NAME = IO INSTRUMENT_NAME = "NEAR INFRARED MAPPING SPECTROMETER" INSTRUMENT_ID = NIMS OBSERVATION_NAME = G1INCHEMIS01A START_TIME = 1996-06-28T03:11:02Z STOP_TIME = 1996-06-28T03:11:59Z SPACECRAFT_CLOCK_START_COUNT = "3498838.00.0" SPACECRAFT_CLOCK_STOP_COUNT = "3498838.86" PRODUCT_ID = "G1INCHEMIS01A_MSY04.IOF" ! of the g-cube or PRODUCT_CREATION_TIME = 1998-06-02 ! tube accompanying NOTE = "These 'images' are digital versions of a hardcopy 'mask' produced with the spectral image cube of an observation, and serve as 'browse' products for the cube. The full mask consists of an RGB summary image generated from 3 bands (or 3 functions of several bands) selected from the cube, histograms of the summary image before and after stretching, a 2-D histogram of the cube, 6 average spectra selected from (and keyed to) areas in the summary image, and annotation about the summary image, the cube and the observation. The thumbnail contains only the summary image. Both images, as well as this label, are linked from an HTML file which also links to other products of observations of the same target taken during the same orbit of Jupiter. These HTML files are themselves linked from WELCOME.HTM in the root directory of this CD-ROM. The entire structure comprises the Galileo NIMS Mask Browser." ^JPEG_DOCUMENT = "G1I001.JPG" ^GIF_DOCUMENT = "G1I001.GIF" OBJECT = JPEG_DOCUMENT DOCUMENT_NAME = "Galileo NIMS Mask" PUBLICATION_DATE = 1998-06-22 DOCUMENT_TOPIC_TYPE = "COMPOSITE IMAGE" INTERCHANGE_FORMAT = BINARY DOCUMENT_FORMAT = JPEG DESCRIPTION = "This document is the full image of the Galileo NIMS mask of an observation, which is a component of the Galileo NIMS Mask Browser on this CD-ROM." END_OBJECT = JPEG_DOCUMENT OBJECT = GIF_DOCUMENT DOCUMENT_NAME = "Galileo NIMS 'Thumbnail'" PUBLICATION_DATE = 1998-06-22 DOCUMENT_TOPIC_TYPE = "COMPOSITE IMAGE" INTERCHANGE_FORMAT = BINARY DOCUMENT_FORMAT = GIF DESCRIPTION = "This document is a 'thumbnail' image of the 3-band RGB spatial display on the Galileo NIMS mask of an observation, a component of the Galileo NIMS Mask Browser on this CD-ROM." END_OBJECT = GIF_DOCUMENT END The DESCRIPTIONs above should be self-explanatory. Most of the keywords in the mask label are also in the cube label and are described in section 11.1. 12 - WHOM TO CONTACT FOR INFORMATION For information pertaining to the contents of this CD-ROM. --------------------------------------------------------- Bob Mehlman UCLA/IGPP Los Angeles, CA 90024-156704 (310) 825-2434 Internet : rmehlman@igpp.ucla.edu NSI/DECnet : JUMPY::RMEHLMAN Helen Mortensen Jet Propulsion Laboratory Mail stop 168-514 4800 Oak Grove Drive Pasadena, CA 91109 (818) 354-4316 Internet : Helen.Mortensen@jpl.nasa.gov THE ISIS SYSTEM --------------- To obtain the VAX/VMS version of the ISIS system ------------------------------------------------ Elias Barbinis, NIMS Librarian Jet Propulsion Laboratory Mail stop 183-601 4800 Oak Grove Drive Pasadena, CA 91109 (818) 354-3214 Internet : ebarbinis@issac.jpl.nasa.gov NSI-Decnet : NIMI::ISISMGR Technical questions on ISIS NIMS cube generation ------------------------------------------------ Bob Mehlman UCLA/IGPP Los Angeles, CA 90024-156704 (310) 825-2434 Internet : rmehlman@igpp.ucla.edu NSI-DECnet: JUMPY::RMEHLMAN ISSAC::RMEHLMAN Technical questions on generic ISIS capability, and requests for one of the Unix versions of the ISIS system. ---------------------------------------------- James Torson U.S. Geological Survey 2255 N. Gemini Flagstaff, AZ 86001 (602) 556-7258 Internet : jtorson@flagmail.wr.usgs.gov THE VICAR SYSTEM ---------------- To obtain the Vicar system ------------------------------------------------------------- Danika Jensen Multimission Image Processing System MS 168-414 Jet Propulsion Laboratory 4800 Oak Grove Drive Pasadena, CA 91109 (818) 354-6269 Internet: Danika.Jensen@jpl.nasa.gov Technical questions on Vicar NIMS cube generation ------------------------------------------------- Lucas Kamp Jet Propulsion Laboratory Mail stop 168-414 4800 Oak Grove Drive Pasadena, CA 91109 (818) 354-3214 Internet : lkamp@nimi.jpl.nasa.gov NSI-Decnet : NIMI::LKAMP ADDITIONAL INFORMATION ---------------------- Information about CD-ROM Hardware and Software and for general assistance in CD-ROM use. -------------------------------------------------- Data Distribution Laboratory Jet Propulsion Laboratory MS 171-264 4800 Oak Grove Drive Pasadena, CA 91109 (818) 354-9343 Electronic mail address: Internet: DDL@stargate.jpl.nasa.gov JPL's Data Distribution Lab has produced a "Catalog of Scientific CD-ROM Publications". This document describes the Planetary CD-ROM collections and the various CD-ROM titles produced by government agencies. It also identifies software which is available for displaying and processing these data sets. The catalog can be ordered from: Jet Propulsion Laboratory Planetary Data System, PDS Operator 4800 Oak Grove Dr. Mail Stop 202-101 Pasadena, CA 91109 (818) 354-4321 (and ask for PDS Operator) INTERNET - pds_operator@jpl.nasa.gov Information about other PDS Data Products can also be obtained from the PDS Operator listed above. 13 - ACKNOWLEDGEMENTS The National Aeronautics and Space Administration is charged with the responsibility for coordination of a program of systematic exploration of the planets by U.S. spacecraft. To this end, it finances spaceflight missions and data analysis and research programs administered and performed by numerous institutions. These include the Galileo NIMS project, the University of California at Los Angeles and the Planetary Data System which involves the U.S. Geological Survey and Jet Propulsion Laboratory. The NIMS Cube CDs were designed by Bob Mehlman (UCLA/IGPP) and Bill Smythe (JPL) of the NIMS team, with the advice and assistance of Eric Eliason (USGS/Flagstaff and PDS Imaging node) and Valerie Henderson & Tyler Brown (JPL and PDS Central node). Bob Mehlman wrote most of the documentation for this CD, with contributions from Bob Carlson, Bill Smythe and Lucas Kamp. He also wrote the programs which generated the index table, the detached mask labels, and the checksums for the cube/tube labels. In doing so, he adapted documentation and software written for the NIMS EDR CDs by Chris Isbell (USGS/Flagstaff). Frank Leader (UCLA/IGPP) of the NIMS team contributed the NIMS observation catalog, and adapted his NIMS Guides of the various encounters for inclusion on the CD, with new contributions by Jim Shirley and Bob Mehlman. Valerie Henderson and Tyler Brown checked the file labels, format and contents of the CD for adherence to PDS standards. Sue Hess and Peter Kahn (JPL and PDS Central node) contributed to earlier volumes. At MIPS, the g-cubes, tubes and masks were generated by Jan Yoshimizu using VICAR software written principally by Lucas Kamp (MIPS/JPL and NIMS team) with contributions by Justin McNeill (MIPS) and Bob Mehlman. Jan also did most of the production work for the CD. She generated the index files and mask labels, collected and validated the data and ancillary files and did the pre-mastering. Doug Alexander contributed to earler volumes. Helen Mortensen provided advice and supervision. 14 - REFERENCES 1. R. W. Carlson, P. R. Weissman, W. E. Smythe, J. C. Mahoney, and the NIMS Science and Engineering Teams, "Near-Infrared Mapping Spectrometer Experiment on Galileo", Space Science Reviews 60, 457-502, 1992. [This volume also contains papers describing the other Galileo instruments.] 2. Irving M. Aptaker, "A near-infrared mapping spectrometer for investigation of Jupiter and its satellites", SPIE 331 ("Instrumentation in Astronomy IV") IV", 182-196, 1982. 3. R. W. Carlson, "Spectral mapping of Jupiter and the Galilean satellites in the near infrared", SPIE 268 ("Imaging Spectroscopy"), 29-34, 1981. 4. R. W. Carlson et al, "Galileo Infrared Imaging Spectroscopy Measurements at Venus", Science, 253, 1541-1548, 27 September 1991. [This issue of Science also contains papers describing Venus data taken by the other Galileo instruments.] 5. Planetary Data System, April (1995), Planetary Data System Data Preparation Workbook, JPL D-7669, Part 1, Version 3.1. Distributed by the Planetary Data System, Jet Propulsion Laboratory. 6. Planetary Data Systems Standards Reference, version 3.2 (1995), JPL D-7669, Part 2. Distributed by the Planetary Data System, Jet Propulsion Laboratory. 7. Planetary Science Data Dictionary Document, (1992), JPL D-7116, Rev C. Distributed by the Planetary Data System, Jet Propulsion Laboratory. 8. ISIS System Design (ISD), VAX/VMS Build 2 Version, Sept. 28, 1994. Distributed by ISIS Librarian (see section 12 above). 9. ISIS User's Manual, Aug. 25, 1995. Distributed by NIMS Librarian. 10. ISIS Programmer's Manual, Aug. 25, 1995. Distributed by NIMS Librarian. 11. "Systematic Trends in GLL Scan Platform Pointing Errors for VE11, with Application to NIMS Systematic Processing", L.W.Kamp, 29 Mar.1991, 384-IPL/MIPS-91-060. 12. "Pointing Corrections for NIMS EV06 Observations", L.W.Kamp, 24 June 1991, 384-IPL/MIPS-91-137. 13. "Status report on attempts to correct Galileo scan platform pointing for LUNAR7", L.W.Kamp, 24 Aug.1992, 384-IPL/MIPS-92-182. 14. "Preliminary assessment of AACS pointing accuracy in E-2 (Rev.2)", 22 Feb.1993, 384-IPL/MIPS-93-022. 15. "E2 Flood Mode Data Analysis: Post-SCALPS scan platform stability" Frank Leader & Lucas Kamp, 18 Feb.1994, IOM NIMS 94-001-FEL. 15 - NIMS PUBLICATIONS F. P. Fanale, J. C. Granahan, T. B. McCord, G. Hansen, C. A. Hibbits, R. Carlson, D. Matson, A. Ocampo, L. Kamp, W. Smythe, F. Leader, R. Mehlman, R. Greeley, R. Sullivan, P. Geissler, C. Barth, A. Hendrix, B. Clark, P. Helfenstein, J. Veverka, M. Belton, K. Becker, T. Becker and the Galileo NIMS, SSI, UVS Teams, "Galileo's Multi-instrument View of Europa's Surface Composition", Icarus 139, 179-188, 1999. Fred Taylor and Patrick Irwin, "The clouds of Jupiter", Astronomy and Geophysics, 40(3), June 1999. M. Roos-Serote, P. Drossart, E. Lellouch, Th. Encrenaz, R. W. Carlson and F. E. Leader, "Comparison of Five-micron Jovian Hot Spot Measurements by ISO SWS, Galileo NIMS and Voyager IRIS", Icarus, 137, 315-340, 1999. R. W. Carlson, M. S. Anderson, R.E. Johnson, W. D. Smythe, A. R. Hendrix, C. A. Barth, L. A. Soderblom, G. B. Hansen, T. B. McCord, J. B. Dalton, R. N. Clark, J. H. Shirley, A. C. Ocampo and D. L. Matson, "Hydrogen Peroxide on the Surface of Europa", Science, 283, 2062-2064, 26 March 1999. R. W. Carlson, "A Tenuous Carbon Dioxide Atmosphere on Jupiter's Moon Callisto", Science, 283, 820-821, 5 February 1999. R. W. Carlson et al, "Surface Composition of the Galilean Satellites from Galileo Near-Infrared Mapping Spectroscopy", in Highlights of Astronomy, ed. J. Anderson, 11B, 1078-1081, 1998. R. W. Carlson, K. H. Baines, T. Encrenaz, P. Drossart, M. Roos-Serote, F. W. Taylor, P. Irwin, A. Weir, S. Smith and S. Calcutt, "Near-IR Spectroscopy of the Atmosphere of Jupiter", in Highlights of Astronomy, ed. J. Anderson, 11B, 1050-1053, 1998. P. G. Irwin, A. L. Weir, S. E. Smith, F. W. Taylor, A. L. Lambert, S. B. Calcutt, P. J. Cameron-Smith, R. W. Carlson, K. Baines, G. S. Orton, P. Drossart, T. Encrenaz and M. Roos-Serote, "Cloud structure and atmospheric composition of Jupiter retrieved from Galileo NIMS real-time spectra", J. Geophys. Res., 103 (E10), 23001-23022, 1998. [This and the next 2 papers are part of a special JGR issue on the Galileo Probe Mission to Jupiter.] M. Roos-Serote, P. Drossart, T. Encrenaz, E. Lellouch, R. W. Carlson, K. H. Baines, L. Kamp, R. Mehlman, G. S. Orton, S. Calcutt, P. Irwin, F. Taylor and A. Weir, "Analysis of Jupiter North Equatorial Belt Hot spots in the 4-5 um range from Galileo/NIMS observations: measurement of cloud opacity, water and ammonia", J. Geophys. Res., 103 (E10), 23023-23042, 1998. P. Drossart, M. Roos-Serote, T. Encrenaz, E. Lellouch, K. H. Baines, R. W. Carlson, L. W. Kamp, G. S. Orton, S. Calcutt, P. Irwin, F. Taylor and A. Weir, "The solar reflected component in Jupiter's 5-micron spectra from NIMS/Galileo observations", J. Geophys. Res., 103 (E10), 23043-23050, 1998. T. B. McCord, G. B. Hansen, R. N. Clark, et al, "Non-water-ice constituents in the surface material of the icy Galilean satellites from the Galileo NIMS investigation", J. Geophys. Res., 103 (E4), 8603-8626, 1998. T. B. McCord, G. B. Hansen, F. P. Fanale, et al, "Salts on Europa's surface", Science 280, 1242-5, 22 May 1998. S. Doute, "Teledetection hyperspectrale des surfaces glacees du systeme solaire: Presentation d'un outil de modelisation numerique applique a l'etude de Triton, Pluton et Io", These, Laboratoire de Glaciologie et Geophysique de l'Environnement, 1998. M. Roos-Serote, "Spectro-imagerie de Venus et Jupiter: Interpretation des observations Galileo/NIMS", These de Doctorat, Universite Paris VI, 1997. R. Lopes-Gautier, A. G. Davies et al, "Hot spots on Io: Initial results from Galileo's near infrared mapping spectrometer", Geophys. Res. Lett., 24 (20), 2439-2442, 1997. A. G. Davies, A. S. McEwen et al, "Temperature and area constraints on the South Volund Volcano on Io from the NIMS and SSI instruments during the Galileo G1 orbit", Geophys. Res. Lett., 24 (2), 2447-2450, 1997. R. W. Carlson, W. D. Smythe et al, "The distribution of sulfur dioxide and other infrared absorbers on the surface of Io", Geophys. Res. Lett., 24 (20), 2479-2482, 1997. T. B. McCord, R. W. Carlson et al, "Organics and Other Molecules in the Surfaces of Callisto and Ganymede", Science 278, 271-275, 10 October 1997. Th. Encrenaz, P. Drossart et al, "Infrared observations of the Jovian atmosphere by Galileo", in "The Three Galileos, the Man, the Spacecraft, the Telescope", Kluwer Academic Press, 1997. Th. Encrenaz, P. Drossart, R. W. Carlson and G. Bjoraker, "Detection of H2O in the splash phase of G- and R-Impacts from NIMS-Galileo, Planet. Space Sci, 45, 1189-1196, 1997. R. W. Carlson, P. Drossart, Th. Encrenaz, P. R. Weissman, J. Hui and M. Segura, "Temperature, size and energy of the Shoemaker-Levy 9 G-Impact fireball", Icarus 128, 251-274, 1997. R. Carlson, W. Smythe et al, "Near-Infrared Spectroscopy and Spectral Mapping of Jupiter and the Galilean Satellites: Results from Galileo's Initial Orbit", Science, 274, 385-388, 18 October 1996. W. D. Smythe, R. Lopes-Gautier et al, "Galilean satellite observation plans for the near-infrared mapping spectrometer experiment on the Galileo spacecraft", J. Geophys. Res., 100 (E9), 18957-18972, 1995. R. W. Carlson, P. R. Weissman et al, "Some timing and spectral aspects of the G and R collision events as observed by the Galileo Near Infrared Mapping Spectrometer", Proceedings, European SL-9/Jupiter Workshop, European Southern Observatory, 69-73, 1995. R. W. Carlson et al, "Galileo infrared observations of the Shoemaker-Levy 9 G impact fireball: a preliminary report", Geophys. Res. Lett., 22, 1557 (1995). M. Roos-Serote, P. Drossart, Th. Encrenaz, E. Lellouch, R. W. Carlson, K. H. 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