NSSDCA ID: PSSB-00739
Availability: Archived at NSSDC, accessible from elsewhere
This description was generated automatically using input from the Planetary Data System.
Data Set Overview ================= This data set contains Raw data taken by New Horizons Linear Etalon Imaging Spectral Array instrument during the PLUTOCRUISE mission phase. LEISA is an infrared imaging spectrometer. The two-dimensional (2-D) detector is a 256x256-pixel array. Spectral separation is done with a wedged optical etalon filter, which comprises high (2.1-2.25 micron) and low (1.25-2.5 micron) spectral resolution segments. The optics and filter arrangement configure one detector dimension as spatial at constant wavelength and the other dimension as both spectral and spatial. Multiple frames (images) may be taken in sequence, while scanning the Field Of View (FOV) in the spatial+spectral dimension, such that each pixel-sized piece of the observed target will be observed at all wavelengths across multiple frames. The resulting data products in this data set are three-dimensional image cubes, which dimensions are spatial, spatial+spectral, and spatial+time and which shall be convolved into spatial, spatial, and spectral image cubes at a later date. RALPH data taken during Annual CheckOuts 1 through 8 (ACO1-8): ============================================================== Summary (Note 1): ================= - Calibrations and other tests with possible science targets - Neptune as a navigation test target - Sun in Solar Illumination Assembly (SIA) - Vega and Arcturus (star) - Pluto encounter rehearsal in the summer of 2013 - 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_LEISA_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. LSB_0123456789_0X53C_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 ** =========== ================================== ============= LEISA LSB, LRW 0X53C - 0X54E * * 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 ===== =========== LSB LEISA, Read minus Reset data LRW LEISA, Raw Read and Reset data 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) ===== =================================== 0x53c - LEISA Lossless (CDH 1)/LRW,LSB 0x54b - LEISA Lossless (CDH 2)/LRW,LSB 0x53d - LEISA Packetized (CDH 1)/LRW,LSB 0x54c - LEISA Packetized (CDH 2)/LRW,LSB 0x53e - LEISA Lossy (CDH 1)/LRW,LSB 0x54d - LEISA Lossy (CDH 2)/LRW,LSB Instrument description ---------------------Refer to the following files for a description of this instrument. CATALOG LEISA.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_LEISA_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
These data are available on-line from the Planetary Data System (PDS) at:
https://pdssbn.astro.umd.edu/holdings/nh-x-leisa-2-plutocruise-v1.0/
Questions and comments about this data collection can be directed to: Dr. David R. Williams
Name | Role | Original Affiliation | |
---|---|---|---|
Dr. Alan Stern | Data Provider | NASA Headquarters | alan.stern@nasa.gov |
Dr. Brian Carcich | General Contact | Cornell University | carcich@astro.cornell.edu |