NSSDCA ID: PSSB-00774
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 Calibrated data taken by New Horizons Long Range Reconnaissance Imager instrument during the PLUTO mission phase. LORRI is a narrow angle (Field Of View, FOV = 0.29 degree square), high resolution (5 microradian/pixel), telescope. A two-dimensional (2-D) CCD detector, with 1024x1024 pixels (optically active region) operates in standard frame-transfer mode. LORRI can also perform on-chip 4x4 binning to produce images of 256x256 pixels. LORRI has no color filters and so provides panchromatic imaging over a wide bandpass extending approximately from 350 nm to 850 nm. The common data product is a 2-D image of brightnesses that is, or can be, calibrated to radiance. During the Pluto mission phase starting in January, 2015, there were several sub-phases: three Approach sub-phases, (AP1, AP2 and AP3); a CORE sequence for the Pluto flyby on 14.July, 2015 (Day Of Year 195), sometimes also referred to as NEP (Near-Encounter Phase); three Departure sub-phases (DP1, DP2, DP3). For this first LORRI delivery for the Pluto mission phase, this data set includes only the Approach data plus the subset of the CORE sequence data that was downlinked through the end of July, 2015. The rest of the Pluto data will be delivered in future versions of this data set according to the schedule worked out by the Project and NASA. This dataset includes (1) Non-Critical and Critical Optical Navigation (OpNav) observations; (2) Hazard observations; (3) Observations of Pluto, Charon, Nix, Hydra, Kerberos, and Styx during Approach; and (4) Pluto Encounter observations, from the day before and the day of encounter. Optical Navigation images, identified by NAV in the observation name, were taken regularly up until 2 days before closest approach. This dataset also includes three OpNav images from 2 days after closest approach. Hazard observations were taken in order to perform a detailed search for any objects that could only be seen as the spacecraft neared the Pluto system. Sets of images were taken about every two weeks starting two months before closest approach. Each set had 8 images, with a mosaic of 4 images at two different roll angles. Approach observation objectives were to search for changes with pan imaging over multiple rotations, perform satellite photometry to further resolve the orbits of Kerberos, Styx, and possible other bodies, and image Nix and Hydra. Encounter observation objectives were to obtain maximum resolution imaging of the entire surface of Pluto and Charon at regular longitudinal intervals for cartographic knowledge; to observe Pluto and Charon at a small (12-30 degrees) solar phase angle to support phase integrals; and to obtain regional stereo images of Pluto for stereographic mapping at the highest possible resolution, which is essential for understanding the relief of features on Pluto, and understanding the magnitude of geologic processes and the origin of geologic features. 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_LORRI_PLUTO.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 Operation Center (SOC) at the Southwest Research Institute (SwRI), Department of Space Studies. 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. Calibration =========== Detailed information about calibration of LORRI images is available in the SOC Instrument Interface Control Document (ICD) in the DOCUMENT section of this data set. The LORRI calibration will only be briefly summarized here; refer to the ICD for details about what is summarized here. N.B. The units of the RDR image data are calibrated Data Number (DN); responsivity factors are provided in the PDS label and FITS headers to convert the calibrated DNs to physical units; the factor to use is dependent on the target scene spectrum. Refer to the ICD and othe LORRI documentation [CHENGETAL2008], [MORGANETAL2005] for more detail. Note also that some versions of [CHENGETAL2008], including the published version, have an error in the units of its Figure 9 ordinate. The PDS keyword PROCESSING_HISTORY_TEXT has been provided in each PDS label for calibrated data file with details of the parameters used or calculated and of the calibration files used in the calibration process. The responsivity factors mentioned in the previous paragraph are included there. The calibration of LORRI images involves all of the following steps in order: 1) Bias subtraction 2) Signal linearization 3) Charge transfer inefficiency (CTI) correction 4) Dark subtraction 5) Smear removal 6) Flat-fielding 7) Absolute calibration (conversion to radiance units) Ground testing has demonstrated that the linearization, CTI and dark subtraction steps are not necessary i.e. the output from the Bias subtraction step may be passed directly to Smear removal step. In addition, the calibration procedure calculates the error and a data quality flag for each pixel and includes those results in the calibrated data product as additional PDS OBJECTs (FITS extensions) appended to the main OBJECT with the data image. The quality flag PDS OBJECT is an image of values of the same size as the main IMAGE product, with each quality flag pixel mapped to the corresponding pixel in the main product. A quality flag value of zero indicates a valid pixel; a non-zero value indicates an invalid pixel (e.g. missing data outside the window(s) of data intended to be downlinked). Note that for windowed products, all pixels in an image are not returned in the downlink telemetry. In the raw data, the pipeline sets such pixels to zero DN (Data Number); the calibration processes those zero-DN pixels as if they were real raw values, but also flags them as missing data in the quality flag PDS OBJECT (FITS extension). Displaying such images using an automatic stretch (contrast enhancement) may result in a confusing result with the majority of the displayed image appearing as an inverse of the calibration (calibration of zero values); therefore the quality flag PDS OBJECT should always be checked when looking at these data. Ongoing in-flight calibration observations will be analyzed to assess the long term stability of the calibration, including whether the currently unused steps may need to be implemented in the future. 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. LOR_0123456789_0X630_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 | | | +--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 =========== ================================== ============= LORRI LOR 0X630 - 0X63B * * Not all values in this range are in this data set 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 types of files generated by each ApID along with the instrument designator that go with each ApID: ApIDs Data product description/Prefix(es) ===== =================================== 0x630 - LORRI High-res Lossless (CDH 1)/LOR 0x636 - LORRI High-res Lossless (CDH 2)/LOR 0x632 - LORRI High-res Lossy (CDH 1)/LOR 0x638 - LORRI High-res Lossy (CDH 2)/LOR 0x631 - LORRI High-res Packetized (CDH 1)/LOR 0x637 - LORRI High-res Packetized (CDH 2)/LOR 0x633 - LORRI 4x4 Binned Lossless (CDH 1)/LOR 0x639 - LORRI 4x4 Binned Lossless (CDH 2)/LOR 0x635 - LORRI 4x4 Binned Lossy (CDH 1)/LOR 0x63B - LORRI 4x4 Binned Lossy (CDH 2)/LOR 0x634 - LORRI 4x4 Binned Packetized (CDH 1)/LOR 0x63A - LORRI 4x4 Binned Packetized (CDH 2)/LOR Instrument description ---------------------Refer to the following files for a description of this instrument. CATALOG LORRI.CAT DOCUMENTS LORRI_SSR.* SOC_INST_ICD.* NH_LORRI_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 LORRI Field Of View definitions: /DOCUMENT/NH_FOV.* /DOCUMENT/NH_LORRI_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. The PDS standards 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. 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-PLUTO-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_LORRI_PLUTO.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; that is, some sequences may have failed to execute due to spacecraft events (e.g. safing) and there will be observations associated with those sequences. No attempt has been made during the preparation of this data set to identify if any, or how many, such empty sequences there are, so it is up to the user to compare the times of the sequences to the times of the available observations from the INDEX/INDEX.TAB table 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) over this dataset is 65.184s. 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 LORRI Principal Investigator: Andrew Cheng, Johns Hopkins Univ., Applied Physics Lab Andrew Cheng Johns Hopkins University Applied Physics Laboratory Space Department 11100 Johns Hopkins Road Laurel, MD 20723 USA
These data are available on-line from the Planetary Data System (PDS) at:
https://pdssbn.astro.umd.edu/holdings/nh-p-lorri-3-pluto-v1.0/
Questions and comments about this data collection can be directed to: Dr. David R. Williams
Name | Role | Original Affiliation | |
---|---|---|---|
Dr. Andrew F. Cheng | Data Provider | Applied Physics Laboratory | andrew.cheng@jhuapl.edu |
Dr. Joseph Peterson | General Contact | Southwest Research Institute | joe@boulder.swri.edu |