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PDS_VERSION_ID = PDS3
RECORD_TYPE = STREAM
LABEL_REVISION_NOTE = "
2014-08-23 SwRI:BTCarcich
Updated from comments in PDS peer review on 2014-08-19.
"
OBJECT = TEXT
PUBLICATION_DATE = 2014-10-30
NOTE = "The NH REX Jupiter encounter
Raw VERSION 1.0
Data Archive
Be sure to read the Required Reading
note below before using the data in
this archive.
"
END_OBJECT = TEXT
END
The NH REX JUPITER Raw VERSION 1.0 Data Archive
========================================================================
A Table of Contents for the rest of this file is provided after this Quick
Start section.
Quick Start - New Horizons Radio Science Experiment (REX) data sets
===================================================================
This is an abbreviated guide to the data; many important details have been
omitted for the sake of brevity; refer to the documentation for full details.
REX data comprise two types of measurements:
1) In-phase and Quadrature-phase (cosine and sine; IQ pair) measurements of
~7.2GHz input uplink signals (tones, from the Earth-based Deep Space Network -
DSN), heterodyned- and downconverted-to-baseband, for the purpose of analyzing
the temporal phase and frequency relationship between the received signal and
the on-board Ultra-Stable Oscillator (USO).
2) Radiometry of 4cm-wavelength (7.2GHz) emission e.g. from a body surface.
Continuous REX data-taking is broken up into a series of data files, each file
covering 1024ms is called an observation or REX Output Frame (ROF); this
derives from the on-board partitioning for storage and telemetering to Earth.
Although this description focuses on the data as partitioned into separate
files, a single continuous data-taking activity comprises many of these files.
Users will need to join several files' data to recreate the original
sequence.
Each REX raw data file stores three primary data types from one ROF (1024ms):
1) IQ pair measurements of ~7.2GHz input signals, heterodyned (2.5MHz IF),
filtered (4.5MHz), sampled at 10MHz, downconverted to baseband, and stored as
1250 IQ pairs per file; 14-bit signed integers on-board, stored 16-bit.
2) Radiometry of the 10MHz samples, squared and summed over 102.4ms,
represented as 10 accumulating sums-of-squares per ROF, and reset to zero once
per ROF; 40-bit integers on-board per sum stored as 64-bit integers. The 10th
accumulated sum for each ROF is stored as the first Radiometry value in the
next ROF.
3) Time tags incrementing every 102.4ms, and not reset between ROFs; 24-bit
on-board counter (rollover at 1.4 fortnight) stored as 32-bit integers. Time
tags are an aid both to place each per-ROF file's data into their correct
temporal position within the original continuous data-taking sequence, and to
determine if any data (ROFs) are missing.
Additional data stored in each file include: the original 5088-byte ROF byte
stream, from before packet decommutation, with the individual bytes of the
primary data types (above) interleaved; several types of instrument and
spacecraft housekeeping (HK) data.
The REX calibrated data files contain the same measurements, but the values
are converted to 32-bit floating point and scientific units: IQ pairs are in
Volts; Radiometry is in dBm power derived from calculated incremental sums
over 102.4ms intervals; Time Tags are in seconds.
Each ROF is stored in two files: a FITS file, with suffix .fit, containing the
data; a PDS label file, with suffix .lbl, describing the FITS data layout. The
files are laid out in a hierarchical structure of directories:
<== directory names | file name ==>
data/20110520_016821/rex_0168215489_0x7b3_sci_1.lbl
<+-> <---+--> <--+-> <---+----> <-+-> <+> <+>
V V V V | | V
Top-level Year, MET prefix MET* of | V File suffix; .fit=FITS;
subdirec- Month, 1st 6 MET obser- | Data .lbl=PDS label
ory in Day digits* vation V Type; eng=Raw; sci=Calibrated
data set ApID: Application Process ID
* see below for MET definition 0x7b0/0x7b1=Side A; 0x7b2/0x7b3=Side B
The following example has three files containing three contiguous ROFs:
rex_0235942890_0x7b3_sci_1.fit
rex_0235942891_0x7b3_sci_1.fit (MET = previous MET+1)
rex_0235942893_0x7b3_sci_1.fit (MET = previous MET+2)
The ten-digit MET (Mission Event Time) is the truncated integer time, in
spacecraft clock seconds since launch, of the time of the ROF. Note that since
the ROFs cover 1024ms (1.024s), the METs will jump two seconds, instead of
one, every 43 files in a contiguous sequence (44.032 = 1.024 x 43 > 44).
Usa a PDS (http://pdssbn.astro.umd.edu/tools/tools_readPDS.shtml) or FITS
library (http://fits.gsfc.nasa.gov) to read these data. For the stubborn, a
brief summary of the REX FITS/PDS layout is given here:
FITS files comprise one or more contiguous Data Units (DUs); the first DU is
the Primary DU (PDU); subsequent DUs are Extension DUs (EDUs), numbered from 1
(the PDU is DU 0); each DU comprises a Header section and and an optional,
contiguous Data section; Header and Data sections always start on 2880-byte
boundaries, and will always be padded to a multiple of 2880 bytes. Multi-byte
binary values (e.g. 32-bit float; 16-bit integers, etc.) are MSByte-1st.
REX quantities are stored in binary form in FITS files.
PDS labels define DU sections in FITS files; PDS labels contain human- and
machine-readable 'KEYWORD = VALUE' statements. Pointer statements (starting
with a caret, ^) provide the ordinal, within the file, of the first
fixed-length 2880-byte record of each DU; here is an example:
<==FITS file sections===> <=Corresponding PDS Label KEYWORD = VALUE lines=>
[PDU Header ]
[PDU Data - Raw ROF ] ^IMAGE = ("REX_0037927970_0X7b*.FIT", 10)
[EDU 1 Header ]
[EDU 1 Data; IQ Pairs ] ^EXTENSION_IQVALS_TABLE = ("REX_003792*.FIT", 12)
[EDU 2 Header ]
[EDU 2 Data; Rad. & TTag] ^EXTENSION_RAD_TIME_TAGS_TABLE = ("REX*.FIT", 16)
The Raw ROF starts at byte 25921 (10*2880-2779) of the file; IQ Pairs at byte
31681 (12*2880-2779); Radiometery and Time Tags at byte 43201 (16*2880-2779).
The PDS TABLE object describes the layout and format of the values in the FITS
Data section; refer to this //-annotated, truncated sample PDS TABLE object:
OBJECT = EXTENSION_RAD_TIME_TAGS_TABLE // Start of TABLE OBJECT
ROWS = 10 // There are 10 rows in the table
ROW_BYTES = 12 // There are 12 bytes in each row
COLUMNS = 2 // There are 2 COLUMNs in each row
OBJECT = COLUMN // Start of 1st COLUMN OBJECT description
NAME = "Radiometer" // 1st COLUMN contains Radiometer values
DATA_TYPE = "MSB_INTEGER" // Radiometry is MSByte-first signed integers
BYTES = 8 // Radiometry is 8-byte (64-bit) integers
START_BYTE = 1 // Radiometry values start at 1st byte in row
END_OBJECT = COLUMN // End of 1st COLUMN OBJECT description
OBJECT = COLUMN // Start of 2nd COLUMN OBJECT description
NAME = "Time Tag" // 2nd COLUMN contains Time Tag values
DATA_TYPE = "MSB_INTEGER" // Time Tags are MSByte-first signed integers
BYTES = 4 // Time Tags are 4-byte (32-bit) integers
START_BYTE = 9 // Time Tag values start at 9th byte in row
END_OBJECT = COLUMN // End of 1st COLUMN OBJECT description
Combine the previous two sections: the 10 Radiometry values are 64-bit signed
MSByte-first integers, starting at file ordinal bytes 43201, 43213 (43201+12),
43225, 43237, 43249, 43261, 43273, 43285, 43297, 43309; the 10 Time Tag values
are 32-bit signed MSByte-first integers, starting at file ordinal bytes 43209
(43201+9-1), 43221 (43209+12), 43233, 43245, 43257, 43269, 43281, 43293,
43305, 43317.
Tracking and Navigation Files (TNFs; TRK-2-34 format), if present, are in the
data/tnf/ subdirectory, are summarized in ASCII tables in that same directory,
and are described in the document labeled with file TNFSIS.LBL.
End of Quick Start Section
========================================================================
Table of Contents
=================
Quick Start (above)
Introduction
Required Reading
Processing Level
Volume Format
File Formats
Volume Contents
Data Filenames and Product IDs
Data directory naming convention
Suggested FITS & PDS software
PDS label overview
Generic PDS label details
Whom to Contact for Information
Introduction
============
Science data content
--------------------
This document provides an overview of this dataset of
the New Horizons (NH)
REX JUPITER Raw VERSION 1.0
Data Archive, including a general listing of the dataset contents.
This dataset contains flight data obtained during the
Jupiter encounter
mission phase of the New Horizons mission, taken by the
Radio Science Experiment
instrument of the New Horizons spacecraft.
The New Horizons (NH) Radio Science Experiment (REX) instrument measures radio
signals and comprises two Elements. The primary investigation uses radio
signals from the NASA Deep Space Network (DSN; Ground Element) received by REX
(Flight Element) onboard the NH spacecraft; the direction of transmission is
exclusively uplink from Earth to REX. The analysis method detects phase
perturbations as the signal path moves through the atmosphere or crosses the
limb of a target body. Ancillary investigations are radiometry of
4cm-wavelength thermal emission using only the Flight Element, and of
gravitational parameters using round-trip Earth-spacecraft-Earth measurements
with tracking data from the NH Radio Science Subsystem (tracking data will be
archived in separate, non-REX data sets).
The main REX activity during Jupiter flyby were two calibration scans of the
High Gain Antenna (HGA) across the Jovian disk. New Horizons performed the
scans at ~100 Rj both in- and out-bound, when the angular size of Jupiter
matched the beamwidth of the HGA. The Jovian radiometry exhibited high
precision, and was used to calibrate the REX radiometric response.
Other activities during this phase, not associated with Jupiter and with the
purpose of characterizing REX, were standard checkout operations, looking for
weak tones in the REX band via a large gain, mapping the HGA beam pattern, and
an interference test with other instruments.
Refer to the data sequence list file
DOCUMENT/SEQ_REX_JUPITER.*
for descriptions of the sequences that generated these data
(see also Note 2 below).
Extensive preparation is necessary to properly understand and interpret
the data in this data set. Although some detail is provided here, this
file is only intended as an introduction to and starting point for this
data set; refer to the Required Reading section below for further
guidance.
Boilerplate disclaimer
----------------------
All NH raw and calibrated data sets were generated in similar fashion by
an automated pipeline; as such, much of the information that follows is
boilerplate common to all such NH data sets. Refer to the data set
catalog (CATALOG/DATASET.CAT) and documentation (DOCUMENT/), as well as
the Required Reading section below, for information specific to the
instrument and data of this data set.
Note about start and stop times
-------------------------------
The start and stop times of data products in some NH data sets may
overlap the ***NOMINAL*** start and stop times, i.e.
2007-01-01T00:00:00 and 2007-06-27T00:00:00 UTC,
respectively, of that mission phase (see also Note 1 below).
See the Mission catalog file NH.CAT in the /CATALOG/ directory for a
description of the New Horizons mission, including a description of
mission phases.
Note 1: Because single data products may span from milliseconds to days
of data, their start time may precede, or their stop times may
follow, the mission ***NOMINAL*** phase start or stop times,
respectively. Refer to CATALOG/DATASET.CAT for the exact start
and stop times of data in this data set.
Note 2: Some planned sequences in that list were not executed, due to
operational considerations such as spacecraft safing events, so
some sequences will have no corresponding data.
Required Reading
================
Almost all of the New Horizons instruments have complex modes of operation
and complex, multi-part data products; users who want to properly understand
these data should expect to spend a significant effort (at least a day per
instrument) reading about and researching the instrument, the data and the PDS
product formats. To support that, the data producer has provided the
following Required Reading list.
Required Reading Summary List (see Details below for suggested priority)
------------------------------------------------------------------------
In this file (sections and subsections below):
Details (next subsection of Required Reading)
Data Filenames and Product IDs
Data directory naming convention
Explanation of granularity
Suggested FITS & PDS software
PDS label overview
Under the /DOCUMENT/ subdirectory:
SOC_INST_ICD.* Science Operations Center Interface Control Document
REX_SSR.* Space Science Review (SSR) Instrument paper
PAYLOAD_SSR.* Space Science Review (SSR) Payload paper
DOCINFO.TXT Summary of /DOCUMENT/ subdirectory
NH_MISSION_TRAJECTORY.* NH Trajectory table for mission
NH_TRAJECTORY.* NH Trajectory table for Jupiter Encounter
SEQ_REX_JUPITER.* Sequence list for this data set
Under the /CATALOG/ subdirectory:
DATASET.CAT NH Data Set Catalog objects
NH.CAT NH Mission Catalog objects
NHSC.CAT NH SpaceCraft catalog objects
REX.CAT NH Instrument catalog objects
REF.CAT References to other documents
CATINFO.TXT Summary of /CATALOG/ subdirectory
Under the /CALIB/ subdirectory:
CALINFO.TXT Summary of calibration files in /CALIB/ subdirectory
Details
-------
The information contained in all documents included with, and
referenced in, this archive, is an integral part of this archive.
Specifically, the information contained in the SOC Instrument
Interface Control Document (ICD), and in the documents submitted
for publication in Space Science Reviews in 2007, is crucial to
understanding the data in this archive. As such, the producers
of this archive have included the best possible version of these
documents with this archive.
* SOC Instrument Interface Control Document (AKA the ICD)
The ICD specifies the interfaces between the New Horizons
Science Operations Center (SOC) and the instrument pipeline, which
process data from raw to calibrated units. The ICD's purpose is to
define the various aspects of the interfaces in sufficient detail
to establish a clear understanding between the SOC and the
instrument team to allow for a parallel pipeline development.
This file is located in the /DOCUMENT/ directory of this
data set and its filename is SOC_INST_ICD.PDF. Other versions
of this file in different formats may be listed in SOC_INST_ICD.LBL.
In addition to mission-wide information (approximately six pages), the
ICD contains an entire section devoted to the details of the
REX instrument (~16 pages). The most important aids provided
to the user of this archive by the ICD are
* Descriptions of the data files that comprise the
data portion of this archive.
* Descriptions of the calibration methodology of the
REX instrument data.
* Overview descriptions of the REX instrument theory
and operations.
* References to more detailed documentation.
* REX Space Science Reviews documents (AKA SSR paper(s))
Scientific papers describing the New Horizons mission,
spacecraft, mission design, payload and instruments were submitted
to the publication Space Science Reviews in 2007 after the Jupiter
encounter; refer to the references catalog for full citations.
These files are located in the /DOCUMENT/ directory of this
data set.
The filename of the instrument SSR paper is REX_SSR.PDF;
other versions of this file are listed in REX_SSR.LBL.
The filename of the payload SSR paper is PAYLOAD_SSR.PDF;
other versions of this file are listed in PAYLOAD_SSR.LBL.
The REX instrument and payload overview SSR papers, I.E.
Tyler, G.L., et al., 2008 [TYLERETAL2008]
and
Weaver, H.A., et al., 2008 [WEAVERETAL2008],
provide details of the REX theory, design, ground testing
and calibration, operational considerations, and post-launch
checkout results.
Because of time and copyright restrictions, the SSR papers could not
be included in this archive in their peer-reviewed and published form.
However, Space Science Reviews did agree to allowing the submitted
versions of these papers to be included in this archive. This has
been done with the initial version of this archive as a convenience
to the user of this archive. However, it should be noted that
There were changes made to the submitted papers before they
were published. Where any differences exist between the
submitted versions of these documents in this archive and the
final published versions, the final published versions are
considered authoritative, and it is up to the user of this
archive to assess if any such differences will affect their
use of this archive.
Other important documents are available in the following files:
NH Trajectory table through Jupiter Encounter:
/DOCUMENT/NH_TRAJECTORY.*
- Includes Jupiter-centric ephemeris in Jupiter frame
NH Heliocentric Trajectory table for mission
/DOCUMENT/NH_MISSION_TRAJECTORY.*
REX Field Of View definitions:
/DOCUMENT/NH_FOV.*
/DOCUMENT/NH_REX_V###_TI.TXT
Further pointers to important documents for this data set
are available in the following files:
/CATALOG/CATINFO.TXT
/CATALOG/REF.CAT
/CALIB/CALINFO.TXT
/DATA/DATAINFO.TXT (not present in all data sets)
/DOCUMENT/DOCINFO.TXT
All reasonable efforts have been made to include the documents in
multiple formats in the document portion of this archive. Where such
inclusion was not possible due to copyright restrictions, references
to the documents have been included in this archive, and it is
up to the user of this archive to obtain a copy of such documents.
The original format of the ICD was MSWORD, and the original format
of the SSR papers was PDF, as noted above. All other formats may
show some loss in quality, especially in images, so the user is
encouraged to get the best possible version of these documents.
Processing Level
================
This data set contains Raw data, one of the two
levels of processed data provided by the NH project to PDS.
A brief discussion of processing levels follows:
Processing Description
Level => CODMAC Level
========== ===============
Raw Instrument telemetry formatted for scientific use
=> CODMAC Level 2
Calibrated Raw data converted to scientific units
=> CODMAC Level 3
N.B.: Raw and Calibrated data are sometimes referred to as EDR
(Engineering Data Records) and RDR (Reduced Data Records),
respectively.
Raw data are in instrument units, typically binary integers referred to
as COUNTs or DATA NUMBER (DN). The raw data are stored in data files
with ancillary information such as observation time timestamps and
observational geometry.
Calibrated data are in scientific or engineering units, such as
radiance (W/(m**2 um sr)) or impact particle mass (GRAMs). The
conversion to calibrated data from raw data was performed according
to an instrument performance model, which was developed from
scientific analysis of ground- and inflight-calibrations, and which
is documented in files in this data set under the DOCUMENT/ and
CALIB/ subdirectories. Refer to to DOCUMENT/DOCINFO.TXT and
CALIB/CALINFO.TXT for pointers to more information.
N.B.: Not all data sets will have CALIB/ directories.
Volume Format
=============
This volume has been formatted according to the PDS Standards
Reference 3.8 version current as of this data set's publication date.
File Formats
============
All text documents and other meta information files such as
descriptions, PDS object definitions and detached PDS labels are
stream format files, with a carriage return (ASCII 13) and a line
feed character (ASCII 10) at the end of the record. This allows
the files to be read by most current operating systems.
Data are provided in FITS format with detached PDS labels; the FITS
files are the same as those generated by the NH Project data
processing pipeline and used by the by NH instrument teams. Users
comfortable with FITS format are welcome to use FITS libraries or other
tools to parse and read the data directly from the FITS files; all
others are advised to access the data through the lens of the detached
PDS labels.
See the
Suggested FITS & PDS software
PDS label overview
sections below for approaches to reading the data.
If the user does not have the skills and/or resources to read these
data, they should contact the Planetary Data System (PDS) for support,
or hire a competent programmer to further prepare the data for their
use and analysis.
Volume Contents
===============
Files on this volume are organized into a set of subdirectories
below the top-level directory. The following table shows the general
structure and content of these directories, but does not exhaustively
list every file in each directory. See the *INFO.TXT files in each
top-level sub-directory for specific information about the files
under that directory.
In this table, directory names are surrounded by forward slashes (/),
and the top-level of the volume is indicated by a single forward slash.
Lines preceded with double-asterisks are not present in all data sets.
/ Top level of volume.
|
+-- AAREADME.TXT The AAREADME file; a backup is in /DOCUMENT/
**+-- ERRATA.TXT Description of any known errors or anomalies
+-- VOLDESC.CAT Description of the logical contents of this volume.
|
+--/DOCUMENT/ Directory containing dataset-related documents.
| +-- AAREADME_BU.TXT A backup of the top-level /AAREADME.TXT file
| +-- DOCINFO.TXT Description of files in the DOCUMENT directory.
| +-- *.* Documentation files
| +--/SAMPLES/ Sub-directory containing data samples
| +-- SAMPINFO.TXT Description of files in the SAMPLES dir.
| +-- *.* Data sample files and documentation
|
|--/CATALOG/ Directory containing PDS catalog objects.
| +-- CATINFO.TXT Description of files in the CATALOG directory.
| +-- *.* Catalog files
|
+--/DATA/ Top-level data directory
**| +--DATAINFO.TXT Description of /DATA/ subdirectory
| +--/YYYYMMDD_SCRMET/ Sub-directories of /DATA/ containing data files
| +-- *.* Data files
**| +--/TNF/ Sub-directories of data with tracking files
|
**+--/CALIB/ Top-level directory containing calibration files
**| +-- CALINFO.TXT Description of files in the CALIB directory
**| +-- *.* Calibration files
|
+--/INDEX/ Directory containing index files.
|
+-- INDXINFO.TXT Description of files in the INDEX directory
+-- *.* Index files and labels
Errata
======
The data in this data set are ideally certified with no known errors.
Over time, errors may be brought to the attention of the NH Project and to
PDS; such errors will be documented in file ERRATA.TXT in the top-level
directory of this data set.
Apparent anomalies and other oddities in the data, which are not in error,
will be documented in the CONFIDENCE_LEVEL_NOTE of the data set catalog
(CATALOG/DATASET.CAT).
Data Filenames and Product IDs
==============================
The filenames of data files and the Product IDs of observations adhere
to a common convention e.g.
ALI_0123456789_0X0AB_ENG_1.FIT
^^^ ^^^^^^^^^^ ^^^^^ ^^^ ^\__/
| | | | | ^^
| | | | | |
| | | | | +--File type (includes dot)
| | | | | - .FIT for FITS file
| | | | | - .LBL for PDS label
| | | | | - not part of Product ID
| | | | |
| | | | +-- Version number; SOC-internal
| | | | (Science Operations Center)
| | | | (see Note FN1)
| | | |
| | | +--ENG for Raw data
| | | SCI for Calibrated data
| | | (see Note FN1)
| | |
| | +--Application ID (ApID) of the telemetry data
| | packet from which the data come (see Note FN2)
| |
| +--Spacecraft Receipt Mission Elapsed Time (SCRMET)
|
+--Instrument/observation designator
Note FN1: Version numbers are SOC-internal values; when looking for a
calibrated version of a raw data file, the Instrument, SCRMET
and ApID portion of the filenames will be the same between
the raw and calibrated versions of the same observation, but
the version numbers may differ.
Note FN2: ApIDs may define the type of data taken by the instrument (e.g.
mode) and the path taken by the data from the instrument to the
ground (e.g. compression). Refer to the data set catalog,
CATALOG/DATASET.CAT, and the SOC Instrument ICD for definitions
of the ApIDs that may be present in this data set.
Note that, depending on the observation, the SCRMET in the data
filename and in the Product ID may be similar to the Mission Elapsed Time
(MET) of the actual observation acquisition, but should not be used as an
analog for the acquisition time. The SCRMET is the time that the data
are transferred from the instrument to spacecraft memory and is therefore
not a reliable indicator of the actual observation time. The PDS label
and the index tables are better sources to use for the actual timing of
any observation. The specific keywords and index table column names for
which to look are
* START_TIME
* STOP_TIME
* SPACECRAFT_CLOCK_START_COUNT
* SPACECRAFT_CLOCK_STOP_COUNT
Data directory naming convention
================================
All of the data files in this dataset are under, but not in, the top-level
/DATA/ directory. Sub-directories, based on the SCRMET (see above) of the
top-level /DATA/ directory have been provided to increase the granularity of
data storage locations which in turn keeps there from being too many data
files in any one directory. The granularity implemented is one sub-directory
per 10,000 counts of the SCRMET (see Data Filenames and Product IDs section
above).
The subdirectory names on this volume reflect that granularity. These
names are of the form
YYYYMMDD_SCRMET/
where SCRMET is a grouping of the first six digits of the ten-digit SCRMET
count, and YYYY, MM, and DD are the year, month and day of the first
possible SCRMET corresponding to that six-digit SCRMET prefix. Any data file
will be located in a directory whose six-digit SCRMET prefix matches that
of the data file.
Since each count represents about one second, there may be as many as nine
six-digit SCRMET prefixes with the same YYYYMMDD values. Also, since days
will not start or end exactly on 10,000 count SCRMET boundaries, directories
with the naming convention may span day boundaries. That is, the YYYYMMDD
value corresponding to the start of a 10,000 count SCRMET range may not be
the same as the YYYYMMDD that corresponds to the end of that range.
Explanation of granularity
--------------------------
The granularity of sub-directories under /DATA/ on this volume has been
copied from that used on the Science Operations Center (SOC) where the
data files were originally generated. On the SOC, the same granularity
was implemented across all eight New Horizons instruments' directory
structures. Because the mission instruments generate data files at
varying rates, from one or more data files per second to one or more days
per data file, a compromise granularity of 10,000 SCRMET counts was chosen,
and propagated to this volume.
Suggested FITS & PDS software
=============================
For working with PDS-labeled data, software packages are available
at Planetary Data System (PDS) nodes (as of 2007). Several other options
for reading either FITS or PDS-labeled data are listed here. If not
included in the text below, references to the packages may be either found
at one or more PDS nodes or found via a search engine. Data users
planning to write custom software should refer to the PDS label
description in the subtopics that follow for a general introduction and
to the PDS Standards document available at PDS nodes.
The following URLs were current as of 2007 when the early New
Horizons data sets were delivered; given the availability of search engines
for the World Wide Web, no attempt has been or will be made to update this
information throughout the mission.
Readers and viewers (Package name, format handled by it, and URL):
READPDS PDS http://pdssbn.astro.umd.edu/nodehtml/software.shtml
NASAVIEW PDS http://pds.nasa.gov/tools/software_download.cfm
FV FITS http://heasarc.gsfc.nasa.gov/docs/software/ftools/fv/
DS9 FITS http://hea-www.harvard.edu/RD/ds9/
Development toolkits for IDL (http://www.ittvis.com/idl/):
OAL PDS http://pds-rings.seti.org/toolkits/
ASTRO FITS http://idlastro.gsfc.nasa.gov/
Development toolkits for C & FORTRAN:
OAL PDS http://pds-rings.seti.org/toolkits/
CFITSIO FITS http://heasarc.gsfc.nasa.gov/docs/software/fitsio/
Development toolkit for Python and Perl:
PyFITS FITS http://www.stsci.edu/resources/software_hardware/pyfits/
CFITSIO.pm FITS http://hea-www.harvard.edu/~rpete/cfitsio/
General FITS info and many more references may be found at
The FITS Support Office: http://fits.gsfc.nasa.gov/
N.B. The following description of PDS labels is only meant to be
sufficient to write a program to read the FITS data files in this
data set using the information contained in the corresponding
detached PDS labels in this data set, and is therefore neither a
complete nor PDS-sanctioned exposition of the PDS label format or
PDS standards. For full details of the PDS standards, refer to
the source from which this data set was obtained.
PDS label overview
==================
Under the DATA/ subdirectory of this data set, each PDS label file is a
multi-record flat ASCII file describing the Data Units in a corresponding FITS
data file that represent a single observation or group of observations.
A FITS file is made up of one or more contiguous 2880-byte records. Each
Data Unit (DU) in a FITS data file comprises one or more records. The data in
each DU starts at the first byte of the DU and is arranged as described in the
PDS label. If the data in a DU do not end at a 2880-byte boundary, then that
DU is padded out to the boundary.
Each record in a PDS label is 80 bytes long comprising 78 printable 7-bit
ASCII characters and/or spaces and ending with a carriage return and a line
feed. Most records are of the form
KEYWORD = VALUE
where KEYWORD is the name of a quantity, and VALUE represents the value of
that quantity. Spaces before, after, and between the keyword, the equals
sign, and the value(s) are not significant.
String values may span multiple records, and are usually delimited by (i.e.
enclosed in) double quotes. Strings contain no double quotes. Some string
values, such as UTC times, are not enclosed in quotes.
Most integer & floating point numeric values are displayed without quotes.
Multiple values for a single keyword are indicated by enclosing the values
in parentheses or curly braces and separating the values with commas.
Comments are initiated by a contiguous forward-slash & asterisk pair (i.e.
/*) on the left and continue to the end of a single record where they are
usually terminated by a matching asterisk & forward-slash pair (*/). Whether
or not the terminating pair is present, the comment ends at the end of the
record, and another initiating pair must be present on the next record if that
record is intended to continue the comment.
Blank lines may be inserted between other lines to enhance readability.
1) PDS pointers
Pointers are special cases of keyword/value pairs in the PDS label, and
define where each DU starts in the FITS file; pointers look like this:
^HEADER = "XYZ.FIT" /* Primary Header DU (HDU) */
^IMAGE = ("XYZ.FIT",11) /* Primary DU */
^ERROR_HEADER = ("XYZ.FIT",22) /* Extension #1 HDU */
^ERROR_IMAGE = ("XYZ.FIT",31) /* Extension #1 DU */
^HOUSEKEEPING_HEADER = ("XYZ.FIT",43) /* Extension #2 HDU */
^HOUSEKEEPING_TABLE = ("XYZ.FIT",44) /* Extension #2 DU */
^THRUSTERS_HEADER = ("XYZ.FIT",45) /* Extension #3 HDU */
^THRUSTERS_TABLE = ("XYZ.FIT",51) /* Extension #3 DU */
Pointer keywords HEADER and IMAGE refer to the Primary Header Data Unit
(HDU) and Primary Data Unit, respectively. Pointer keywords that end in
_HEADER refer to Extension HDUs. Pointer keywords that end in _IMAGE or
_TABLE or _ARRAY refer to Extension DUs.
The text after the equals sign in each pointer is usually enclosed by
parentheses and comprises the filename of the file where the DU resides and
the DU's location in that file. The filename and the location are delimited
by a comma. The filename is a string enclosed in double quotes, and the DU
location is a decimal integer value indicating the cardinal location in the
file of the first 2880-byte record of the DU.
For example, the ^IMAGE DU above, with a location value of 11, starts at
an offset of 28800 bytes (= [11-1]*2880) from the first byte of the
file.
If only the filename is given, with neither the parentheses nor the comma
nor the location, then the DU starts at the beginning of the file i.e. the
location is implicitly set to one.
2) OBJECT stanzas
Each pointer in a PDS label will have a corresponding OBJECT stanza.
OBJECT stanzas comprise the lines between corresponding 'OBJECT=<object_name>'
& 'END_OBJECT=<object_name>' keyword lines.
OBJECT stanzas referring to TABLEs will contain one or more
'OBJECT=COLUMN'/'END_OBJECT=COLUMN' stanzas.
See the comments (/* ... */) to the right of the keywords in the example
below to understand the OBJECTs and keywords that describe binary tables.
************************************************************************
********** N.B. This example does not describe every keyword **********
********** that will be present in each table, but only **********
********** those necessary to read and understand the **********
********** arrangement of the data in the DU to which **********
********** OBJECTs refer. Refer to the PDS standards **********
********** for more details. **********
********** Example starts after the next line **********
************************************************************************
^S_TABLE = ("XYZ.FIT",51) /* EDU #3; Data table */
OBJECT = S_TABLE /* Start of object describing data of pointer ^S_TABLE */
INTERCHANGE_FORMAT = BINARY
ROWS = 463 /* Table comprises 463 rows */
COLUMNS = 97 /* Table comprises 97 columns */
ROW_BYTES = 1080 /* Each row comprises 1080 bytes */
DESCRIPTION = "..."
OBJECT = COLUMN /* OBJECT describing column 1 */
NAME = STATUSES /* Column name */
COLUMN_NUMBER = 1 /* Column location within row */
DATA TYPE = MSB_INTEGER /* Column data element type */
ITEMS = 3 /* Number of data elements in column */
ITEM_BYTES = 2 /* Size of each data element in column */
START_BYTE = 1 /* Byte location in row of 1st byte of column */
BYTES = 6 /* Column width (bytes); <= ITEMS*ITEM_BYTES */
DESCRIPTION = "..."
END_OBJECT = COLUMN
OBJECT = COLUMN /* OBJECT describing column 2 */
NAME = TEMPERATURE /* Column name */
COLUMN_NUMBER = 2 /* Column location within row */
DATA TYPE = IEEE_REAL /* Column data type */
ITEMS = 1 /* Number of data elements in column */
ITEM_BYTES = 4 /* Size of each data element in column */
START_BYTE = 7 /* Byte location in row of 1st byte of column */
BYTES = 4 /* Column width (bytes); <= ITEMS * ITEM_BYTES */
DESCRIPTION = "..."
END_OBJECT = COLUMN
...
END_OBJECT = S_TABLE /* End of object S_TABLE */
************************************************************************
********** Example ends before the previous line *****************
************************************************************************
In the example above:
- the table S_TABLE starts at byte 144001 ((51-1)*2880 + 1)
of the file, and comprises 97 rows each of width 1080 bytes.
- the first column, named STATUSES, in each row starts at the
1st byte of that row and comprises three MSB-first 16-bit
integers using 6 bytes total on each row.
- the second column, named TEMPERATURE, in each row starts at
the seventh byte of that row and comprises one IEEE 32-bit
floating point value using four bytes total on each row.
- Subsequent rows are offset 1080 bytes from the previous row.
Generic PDS label details
=========================
The PDS label has meta-data which describe the circumstances surrounding the
data in the FITS file. These meta-data are in keyword and value pairs (e.g.
the pointers above) and each of these keywords is described in the PDS Data
Dictionary plus the New Horizons mission- specific local data dictionary
supplemental items, both of which are available in this archive.
All FITS Header Data Units (HDUs) and Data Units are described in the PDS
labels. In some cases, no Data Unit will be described in the PDS label
because there is nothing to describe i.e. it is not present in the FITS file.
PDS LABELS: Column Descriptions in binary tables
-------------------------------------------------
FITS extensions may contain data that are a subset of
instrument and/or spacecraft housekeeping telemetry packets
formatted as binary tables. Where possible, each column
included in such extensions has a DESCRIPTION field something
like this:
DESCRIPTION = "
Full Mnemonic:
SWAP_RT.SEC64_ST
General Description:
A bit indicating the beginning of a 64-second cycle
Conversion: STATES
- [lo:hi]=state description:
[0:0]=CONT
[1:1]=START
Subsystem: SWAP
Packet ApID: 0X584
Byte Offset within ApID packet: 10
Bit Offset within Byte of ApID packet: 0
Bit Length within ApID packet: 1
Type of value: UNSIGNED
Units: N/A
"
The sub-fields used in these DESCRIPTION fields are as follows:
Full Mnemonic: The complete mnemonic used in the definition
of the packet. The COLUMN name will typically
be a subset of this mnemonic.
General Description: A description of the column
Extended Description: More information
- this field is not always present
Conversion: This item describes the conversion of the value
found in the column to a meaningful quantity.
It takes one of two forms: STATES and polynomial.
If the conversion form is STATES, then the bits of
the column are combined into an integer and compared
against the ranges list. In the example above, if the
value of the bit is zero, then the SWAP_RT.SEC64T
column represents a continuing state. If the value of
the bit is 1, then the SWAP_RT_SEC64T column indicates
that a new 64-second cycle has just begun.
If the conversion form is polynomial, then the bits of
the column are combined into an integer and used as
the independent value of the polynomial with the
coefficients given. For example, if the integer
value of a column is 100, and its conversion looks
like this:
Conversion: polynomial coefficients:
Order 0: 0.925
Order 1: 0.979
Then the derived value of this instrument is
0.925 + (0.979 * 100) = 98.825
Subsystem: Which subsystem generated the packet
Packet ApID: The Application ID of the packet
Byte & Bit Offsets & Bit Length: the location of the column's
value in the packet, including
the 10-byte CCDS header.
Type of value: For integer values, whether the value
is signed or unsigned
Units: Nominal units of the derived column values
Whom to Contact for Information
===============================
New Horizons REX Principal Investigator:
Len Tyler, Stanford University
Len Tyler
350 Serra Mall, David Packard #372
Stanford University
Stanford, CA 94305-9515
USA
New Horizons Science Operation Center (SOC):
Joe Peterson
Southwest Research Institute (SWRI)
Department of Space Studies
1050 Walnut Street, Suite 400
Boulder, CO 80302
USA