| DATA_SET_DESCRIPTION |
Data Set Overview
=================
This data set contains Raw data taken by New Horizons
Multispectral Visible Imaging Camera
instrument during the PLUTOCRUISE mission phase.
MVIC is a visible and near-infrared imager. MVIC comprises seven
separate CCD two-dimensional arrays; all rows are 5024 pixels across
with twelve pixels at either end of each row optically inactive. The
single Pan Frame array is a panchromatic frame-transfer imager, 5024x128
pixels, that typically takes multiple frames in each observation. The
common Pan Frame data product is an image cube in three dimensions:
spatial; spatial; image frame, equivalent to time. Of the remaining six
arrays, 5024x32 pixels each, two are panchromatic (unfiltered), and the
remaining four are under filters and called the color arrays:
Near-InfraRed (NIR); methane (CH4); Red; Blue. All six are operated in
Time-Delay Integration (TDI) mode; the TDI arrays are in some ways
similar to line cameras. In TDI mode, the spacecraft and MVIC boresight
are scanned across the target at a rate that matches the charge transfer
clock rate across the rows of the CCDs. Ideally the rates are matched,
so as the charges are read by the analog-to-digital converter off the
last line of the array, each pixel reading is near-proportional to the
brightness of the same piece of the target as its image moved across the
array, accumulating charge on each row. In TDI mode it is the product of
the per-row charge clock rate and the duration of the observation that
determines the number of rows each the image, and the image can be
arbitrarily long; the number of rows (32) in each array is not relevant
in determining the size of the image. The common data product for each
of the TDI arrays is a 2-D image, of arbitrary length as noted earlier.
RALPH data taken during Annual CheckOuts 1 through 8 (ACO1-8):
==============================================================
Summary (Note 1):
=================
- Science observations
- Uranus with MVIC at a phase angle not available from Earth (44 degrees)
- Neptune with MVIC at a phase angle not available from Earth (34 degrees)
- Calibrations and other tests with possible science targets
- Neptune as a navigation test target
- Sun in Solar Illumination Assembly (SIA)
- M6 and M7 (clusters)
- Pluto encounter rehearsals
- Functional tests
Details:
========
Primary RALPH Calibrations and other major observations (Notes 1 and 2):
------------------------------------------------------------------------
During ACO1, ACO2 and ACO4, RALPH took LEISA calibration data using
the star Vega as a source; During ACO-2 and ACO-4, RALPH took MVIC
calibration data using the clusters M7 and M6.
During ACO1 and ACO2, the RALPH instrument observed flat field data
for both MVIC and LEISA using the SIA. However these data were not
useful for flat fielding because there was varying structure in the
images i.e. the light was not evenly illuminating the field of view,
and details of the flat are dependent on the position of the Sun in
the SIA.
In ACO1, RALPH observations for calibration, characterization and
interference goals included a stray light test with the sun at an
angle of 20-90 degrees from the FOV, to characterize the light leak
of LEISA on the incoming and outgoing encounter asymptote, and an
interference test between the LEISA and ALICE instruments.
During ACO2, RALPH observed Neptune in pan frame mode as an optical
navigation test.
In ACO2, another stray light test was performed. The geometries
simulated observations from the outgoing encounter asymptote with an
elongation angle of 13 degrees (sun-spacecraft-target).
During ACO3 and ACO5, RALPH had no 3-axis (spacecraft not in
spinning mode) observations, only the functional test as described
below.
In ACO4, RALPH performed a dark current test, taking data while the
focal plane cooled down, from 2 to 20h after the decontamination
heaters were turned off. RALPH also performed an interference test,
simultaneously operating LEISA, LORRI and ALICE. MVIC took color
observations of Uranus and Neptune at phase angles not accessible
from Earth (44 degrees and 34 degrees, respectively) and optical
navigation images of Neptune using the pan frame array. MVIC
performed a stray light test as a ride-along to the LORRI observation
in ACO4, and LEISA performed a light leak test at an angle of 9 degrees
from the sun. RALPH also did an interference test between the MVIC TDI
and LORRI modes of operation.
In ACO6 through ACO8, RALPH performed rehearsals of the Pluto
enounter (ACO6; ACO7), LEISA stellar calibrations (ACO6; ACO8), MVIC
stellar calibrations and optical navigation tests (ACO6; ACO7;
ACO8), and LEISA test scans for the flat field (ACO8).
Functional Test
---------------
During all ACOs the RALPH instrument performed one or more
functional tests. This test exercised all modes of the instrument
at two different rates, and both power sides of RALPH. The test
took LEISA raw and subtracted data, and MVIC data using each of the
detectors. The integration times included a short and longer time.
There was no specific target as often these data were taken when the
spacecraft was spinning and the field of view was sweeping across
the sky.
Note 1
======
The items listed above are the major RALPH observations, but in the
interest of brevity may not include every RALPH observation; refer
to the sequence listing for a complete list of all activities.
Every observation provided in this data set was taken as a part of a
particular sequence. A list of these sequences has been provided in
file DOCUMENT/SEQ_MVIC_PLUTOCRUISE.TAB.
N.B. Some sequences provided may have no corresponding observations.
For a list of observations, refer to the data set index table. This
is typically INDEX.TAB initially in the INDEX/ area of the data set.
There is also a file SLIMINDX.TAB in INDEX/ that summarizes key
information relevant to each observation, including which sequence
was in effect and what target was likely intended for the
observation.
Version
=======
This is VERSION 1.0 of this data set.
Processing
==========
The data in this data set were created by a software data
processing pipeline on the Science Operations Center (SOC) at
the Southwest Research Institute (SwRI), Department of Space Operations.
This SOC pipeline assembled data as FITS files from raw telemetry
packets sent down by the spacecraft and populated the data labels
with housekeeping and engineering values, and computed geometry
parameters using SPICE kernels. The pipeline did not resample
the data.
Data
====
The observations in this data set are stored in data files using
standard Flexible Image Transport System (FITS) format. Each FITS
file has a corresponding detached PDS label file, named according
to a common convention. The FITS files may have image and/or table
extensions. See the PDS label plus the DOCUMENT files for a
description of these extensions and their contents.
This Data section comprises the following sub-topics:
- Filename/Product IDs
- Instrument description
- Other sources of information useful in interpreting these Data
- Visit Description, Visit Number, and Target in the Data Labels
Filename/Product IDs
--------------------
The filenames and product IDs of observations adhere to a
common convention e.g.
MC0_0123456789_0X530_ENG.FIT
^^^ ^^^^^^^^^^ ^^^^^ ^^^\__/
| | | | ^^
| | | | |
| | | | +--File type (includes dot)
| | | | - .FIT for FITS file
| | | | - .LBL for PDS label
| | | | - not part of product ID
| | | |
| | | +--ENG for CODMAC Level 2 data
| | | SCI for CODMAC Level 3 data
| | |
| | +--Application ID (ApID) of the telemetry data
| | packet from which the data come
| | N.B. ApIDs are case-insensitive
| |
| +--MET (Mission Event Time) i.e. Spacecraft Clock
|
+--Instrument designator
Note that, depending on the observation, the MET in the data filename
and in the Product ID may be similar to the Mission Event Time (MET)
of the actual observation acquisition, but should not be used as an
analog for the acquisition time. The MET 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
Instrument Instrument designators ApIDs **
=========== ================================== =============
MVIC MC0, MC1, MC2, MC3, MP1, MP2, MPF 0X530 - 0X54A *
* Not all values in this range are in this data set
** ApIDs are case insensitive
There are other ApIDs that contain housekeeping values and
other values. See SOC Instrument ICD (/DOCUMENT/SOC_INST_ICD.*)
for more details.
Here is a summary of the meanings of each instrument designator:
Instr
Dsgn. Description
===== ===========
MC0 MVIC, Color TDI, Red filter
MC1 MVIC, Color TDI, Blue filter
MC2 MVIC, Color TDI, Near-InfraRed (NIR) filter
MC3 MVIC, Color TDI, Methane (CH4) filter
MP1 MVIC, Panchromatic TDI CCD 1
MP2 MVIC, Panchromatic TDI CCD 2
MPF MVIC, Panchromatic frame (5024 pixels)
See SOC Instrument ICD (/DOCUMENT/SOC_INST_ICD.*) for details
Here is a summary of the types of files generated by each ApID
(N.B. ApIDs are case-insensitive) along with the instrument
designator that go with each ApID:
ApIDs Data product description/Prefix(es)
===== ===================================
0x530 - MVIC Panchromatic TDI Lossless (CDH 1)/MP1,MP2
0x53f - MVIC Panchromatic TDI Lossless (CDH 2)/MP1,MP2
0x531 - MVIC Panchromatic TDI Packetized (CDH 1)/MP1,MP2
0x540 - MVIC Panchromatic TDI Packetized (CDH 2)/MP1,MP2
0x532 - MVIC Panchromatic TDI Lossy (CDH 1)/MP1,MP2
0x541 - MVIC Panchromatic TDI Lossy (CDH 2)/MP1,MP2
0x533 - MVIC Panchromatic TDI 3x3 Binned Lossless (CDH 1)/MP1,MP2 *
0x542 - MVIC Panchromatic TDI 3x3 Binned Lossless (CDH 2)/MP1,MP2 *
0x534 - MVIC Panchromatic TDI 3x3 Binned Packetized (CDH 1)/MP1,MP2 *
0x543 - MVIC Panchromatic TDI 3x3 Binned Packetized (CDH 2)/MP1,MP2 *
0x535 - MVIC Panchromatic TDI 3x3 Binned Lossy (CDH 1)/MP1,MP2 *
0x544 - MVIC Panchromatic TDI 3x3 Binned Lossy (CDH 2)/MP1,MP2 *
0x536 - MVIC Color TDI Lossless (CDH 1)/MC0,MC1,MC2,MC3
0x545 - MVIC Color TDI Lossless (CDH 2)/MC0,MC1,MC2,MC3
0x537 - MVIC Color TDI Packetized (CDH 1)/MC0,MC1,MC2,MC3
0x546 - MVIC Color TDI Packetized (CDH 2)/MC0,MC1,MC2,MC3
0x538 - MVIC Color TDI Lossy (CDH 1)/MC0,MC1,MC2,MC3
0x547 - MVIC Color TDI Lossy (CDH 2)/MC0,MC1,MC2,MC3
0x539 - MVIC Panchromatic Frame Transfer Lossless (CDH 1)/MPF
0x548 - MVIC Panchromatic Frame Transfer Lossless (CDH 2)/MPF
0x53a - MVIC Panchromatic Frame Transfer Packetized (CDH 1)/MPF
0x549 - MVIC Panchromatic Frame Transfer Packetized (CDH 2)/MPF
0x53b - MVIC Panchromatic Frame Transfer Lossy (CDH 1)/MPF
0x54a - MVIC Panchromatic Frame Transfer Lossy (CDH 2)/MPF
* as of October, 2014, 3x3 modes have not been used
Instrument description
----------------------
Refer to the following files for a description of this instrument.
CATALOG
MVIC.CAT
DOCUMENTS
RALPH_SSR.*
SOC_INST_ICD.*
NH_RALPH_V###_TI.TXT (### is a version number)
Other sources of information useful in interpreting these Data
--------------------------------------------------------------
Refer to the following files for more information about these data
NH Trajectory tables:
/DOCUMENT/NH_MISSION_TRAJECTORY.* - Heliocentric
RALPH Field Of View definitions:
/DOCUMENT/NH_FOV.*
/DOCUMENT/NH_RALPH_V###_TI.TXT
Visit Description, Visit Number, and Target in the Data Labels
---------------------------------------------------------------
The observation sequences were defined in Science Activity Planning
(SAP) documents, and grouped by Visit Description and Visit Number.
The SAPs are spreadsheets with one Visit Description & Number per row.
A nominal target is also included on each row and included in the data
labels, but does not always match with the TARGET_NAME field's value in
the data labels. In some cases, the target was designated as RA,DEC
pointing values in the form ``RADEC=123.45,-12.34'' indicating Right
Ascension and Declination, in degrees, of the target from the
spacecraft in the Earth Equatorial J2000 inertial reference frame.
This indicates either that the target was either a star, or that the
target's ephemeris was not loaded into the spacecraft's attitude and
control system which in turn meant the spacecraft could not be pointed
at the target by a body identifier and an inertial pointing value had
to be specified as Right Ascension and Declination values. PDS-SBN
practices do not allow putting a value like RADEC=... in the PDS
TARGET_NAME keyword's value. In those cases the PDS TARGET_NAME value
is set to CALIBRATION. TARGET_NAME may be N/A (Not Available or Not
Applicable) for a few observations in this data set; typically that
means the observation is a functional test so N/A is an appropriate
entry for those targets, but the PDS user should also check the
NEWHORIZONS:OBSERVATION_DESC and NEWHORIZONS:SEQUENCE_ID keywords in
the PDS label, plus the provided sequence list (see Ancillary Data
below) to assess the possibility that there was an intended target.
Ancillary Data
==============
The geometry items included in the data labels were computed
using the SPICE kernels archived in the New Horizons SPICE
data set, NH-X-SPICE-6-PLUTOCRUISE-V1.0.
Every observation provided in this data set was taken as a part of a
particular sequence. A list of these sequences has been provided in
file DOCUMENT/SEQ_MVIC_PLUTOCRUISE.TAB. In addition, the
sequence identifier (ID) and description are included in the PDS label
for every observation. N.B. While every observation has an associated
sequence, every sequence may not have associated observations. Some
sequences may have failed to execute due to spacecraft events (e.g.
safing). No attempt has been made during the preparation of this data
set to identify such empty sequences, so it is up to the user to
compare the times of the sequences to the times of the available
observations from INDEX/INDEX.TAB to identify such sequences.
Time
====
There are several time systems, or units, in use in this dataset:
New Horizons spacecraft MET (Mission Event Time or Mission Elapsed
Time), UTC (Coordinated Universal Time), and TDB Barycentric
Dynamical Time.
This section will give a summary description of the relationship
between these time systems. For a complete explanation of these
time systems the reader is referred to the documentation
distributed with the Navigation and Ancillary Information
Facility (NAIF) SPICE toolkit from the PDS NAIF node, (see
http://naif.jpl.nasa.gov/).
The most common time unit associated with the data is the spacecraft
MET. MET is a 32-bit counter on the New Horizons spacecraft that
runs at a rate of about one increment per second starting from a
value of zero at
19.January, 2006 18:08:02 UTC
or
JD2453755.256337 TDB.
The leapsecond adjustment (DELTA_ET = ET - UTC) was 65.184s at
NH launch, and the first three additional leapseconds occured
in at the ends of December, 2009, June, 2012 and June, 2015.
Refer to the NH SPICE data set, NH-J/P/SS-SPICE-6-V1.0, and the
SPICE toolkit docmentation, for more details about leapseconds.
The data labels for any given product in this dataset usually
contain at least one pair of common UTC and MET representations
of the time at the middle of the observation. Other portions
of the products, for example tables of data taken over periods
of up to a day or more, will only have the MET time associated
with a given row of the table.
For the data user's use in interpreting these times, a reasonable
approximation (+/- 1s) of the conversion between Julian Day (TDB)
and MET is as follows:
JD TDB = 2453755.256337 + ( MET / 86399.9998693 )
For more accurate calculations the reader is referred to the
NAIF/SPICE documentation as mentioned above.
Reference Frame
===============
Geometric Parameter Reference Frame
-----------------------------------
Earth Mean Equator and Vernal Equinox of J2000 (EMEJ2000) is the
inertial reference frame used to specify observational geometry items
provided in the data labels. Geometric parameters are based on best
available SPICE data at time of data creation.
Epoch of Geometric Parameters
-----------------------------
All geometric parameters provided in the data labels were computed at
the epoch midway between the START_TIME and STOP_TIME label fields.
Software
========
The observations in this data set are in standard FITS format
with PDS labels, and can be viewed by a number of PDS-provided
and commercial programs. For this reason no special software is
provided with this data set.
Contact Information
===================
For any questions regarding the data format of the archive,
contact
New Horizons RALPH Principal Investigator:
Alan Stern, Southwest Research Institute
S. Alan Stern
Southwest Research Institute
Department of Space Studies
1050 Walnut Street, Suite 400
Boulder, CO 80302
USA
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