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 = 1998-12-10
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)
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.
[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.)
|
|- 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)
| |
| |- MASKDOC.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.
|
|- OBSCAT.TAB Observation characteristics table for phase 2
| (encounters of Jupiter and its satellites)
|
|- OBSCAT.LBL PDS label describing OBSCAT.TAB content.
|
|- OBSCAT0.TAB Observation characteristics table for phase 0.
| (Gaspra, Ida and SL9 encounters)
|
|- OBSCAT0.LBL PDS label describing OBSCAT0.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 thumbprint 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.
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.
(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 - 19 PROFILE_ACTIVITY_ID : The profile activity ID identifies the
type of scan platform activity of the observation segment.
Only the first 4 characters of each identifier are used in
the table:
ALSPINSP All Spin Scan Platform Control
CMDRS Instrument Command (Remote Sensing)
CSMOS Continuous Slew Mosaic
INITRS Instrument Initialization (Remote Sensing)
PCINIT Photocalibration Initialization
PCREST Photocalibration Restore (termination)
RADHTR NIMS Radiometric Heater Control
SCIREC Science Record
SCITLM Science Telemetry
SMOS Start/Stop Slew Mosaic
TARGET Target (Scan Platform Positioning)
SSI Solid State Imaging (SSI) Command
UTIL Utility, such as instrument checkout
21 - 31 NATIVE_START_TIME : The spacecraft clock count that indicates
the beginning of the observation segment.
33 - 43 NATIVE_STOP_TIME : The spacecraft clock count that indicates
the end of the observation segment.
45 - 46 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)
49 - 49 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.
52 - 52 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
55 - 55 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.
56 - 91 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.
56 - 73 PTAB A
56 - 58 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.
61 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.
64 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.
66 - 67 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.
69 - 70 GRATING_POSITION_INCREMENT : The grating position increment
controls the step size between grating positions. It is the
third byte of the PTAB.
72 - 73 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.
74 - 91 PTAB B (see PTAB A above for description and relative location
of fields)
94 - 94 ELECTRONICS_CALIBRATION_FLAG : An electronic calibration of
the NIMS instrument will occur in the first RIM of the
observation if the flag is set.
96 - 96 OPTICAL_CALIBRATION_FLAG : An optical calibration of the NIMS
instrument will occur in the first RIM of the observation
if the flag is set.
98 - 114 START_TIME : The start time of the observation as a
Universal Time in ISO format, corresponding to
NATIVE_START_TIME.
117 - 117 REALTIME_FLAG : If the flag is set, the observation was
transmitted in the realtime data stream.
119 - 119 RECORD_FLAG : If the flag is set, the observation was
recorded on the Galileo tape recorder and transmitted later.
121 - 128 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 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.
15 - NIMS PUBLICATIONS
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.
Baines, F. W. Taylor and S. B. Calcutt, "The thermal structure and dynamics
of the atmosphere of Venus between 70 and 90 kilometers from the Galileo-NIMS
spectra", Icarus 114, 300, 1995.
T. B. McCord, L. A. Soderblom et al, "Galileo infrared imaging spectrometry at
the Moon", J. Geophys. Res., 99 (E3), 5587-5600, 1994.
R. W. Carlson and F. W. Taylor, "The Galileo encounter with Venus: results from
the Near-Infrared Mapping Spectrometer", Planet. Space Sci. 41 (7), 475-476,
1993. [This is the introduction to a special issue devoted to NIMS results
from the Venus encounter (see next 6 references).]
R. W. Carlson, L. W. Kamp et al, "Variations in Venus cloud particle
properties: a new view of Venus's cloud morphology as observed by the Galileo
Near-Infrared Mapping Spectrometer", Planet. Space Sci. 41 (7), 477-485, 1993.
A. D. Collard, F. W. Taylor et al, "Latitudinal distribution of carbon
monoxide in the deep atmosphere of Venus", Planet. Space Sci. 41 (7),
487-494, 1993.
P. Drossart, B. Bezard et al, "Search for spatial variations of the H2O
abundance in the lower atmosphere of Venus from NIMS-Galileo", Planet. Space
Sci., 41 (7), 495-504, 1993a.
P. Drossart, J. Rosenqvist et al, "Earth global mosaic observations with NIMS-
Galileo", Planet. Space Sci., 41 (7), 555-561, 1993b.
D. H. Grinspoon, J. B. Pollack et al, "Probing Venus's cloud structure with
Galileo NIMS", Planet. Space Sci., 41 (7), 515-542, 1993.
M. Roos, P. Drossart et al, "The upper clouds of Venus: determination of the
scale height from NIMS-Galileo infrared data", Planet. Space Sci., 41 (7),
505-514, 1993.
C. Sagan, W. R. Thompson, R. Carlson, D. Gurnett and G. Hord, "A search for
life on Earth from the Galileo spacecraft", Nature, 365, 715-721, 1993.
R. W. Carlson, P. R. Weissman, W. D. 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.]
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.]
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.
R. W. Carlson, "Spectral mapping of Jupiter and the Galilean satellites in the
near infrared", SPIE 268 ("Imaging Spectroscopy"), 29-34, 1981.