Data Set Information
DATA_SET_NAME STARDUST NAVCAM PREFLIGHT CALIB ARCHIVE
DATA_SET_ID STARDUST-CAL-NC-2-PREFLIGHT-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Stardust Navigation Camera Preflight Calibration Image Data Format: : Data Set Overview: : This volume contains the results of the preflight calibration of the Stardust Navigation Camera. The images were collected in an attempt to mimic the environment that the camera would experience during cruise and encounter with the comet Wild-2. The images on this calibration volume are in standard PDS format. Each file includes an attached PDS label at the beginning of the file, followed by a histogram, and ending with the image itself. The PDS label contains two OBJECT definitions, which describe the storage requirements for both the histogram and image objects. The label also describes the circumstances surrounding the collection of the calibration image. This meta-data is in keyword and value pairs and each of these keywords is described at the end of this document. Camera Description: : The camera has a 1024x1024 array as the active portion of the CCD. The images that are stored on this volume, however, contain more than just the active portion of the CCD. Each line contains a sync pattern, a line counter, 12 baseline stabilization pixels, the 1024 pixels from the active portion of the CCD, and finally 8 over-clock pixels used to measure the quantum efficiency. The number of rows for each image is always 1024, no matter what compression mode is used, but the number of columns for each image depends on the compression mode used. Compression Modes: : The navcam images can be either 8-bit or 12-bit data. The 12-bit data is commonly referred to as 'uncompressed data', while the 8-bit is referred to as 'compressed data'. This compression is accomplished by a 12-bit to 8-bit square-root look-up-table compression method, which is implemented in the hardware of the camera electronics. This compression is lossy and the estimate of the 12-bit image can be recovered using the look-up table mentioned in Appendix 3 of the Calibration Document. Both the image and histogram portions of the data file require different amounts of storage space, dependent on the compression mode used. Pixel storage requirements: : In uncompressed mode with 12-bit data, the pixels are expressed in two bytes, as 16 bits per pixel. The upper nibble of the most significant byte is always zero for these images. In compressed mode with 8-bit data, the pixels are expressed in a single byte. Number of Columns within each Row: : The general form of each line for each image is fixed. The row of data from the camera can be categorized into five different regions: 1. Sync Pattern Always 2 bytes, with value 0x0000 2. Line Counter Always 2 bytes, values from 0 to 1023 3. 8 BLS pixels *Baseline Stabilization pixels, either 1 or 2 bytes per pixel 4. 1024 image pixels *Either 1 or 2 bytes per pixel 5. 12 over-clock pixels *Used to measure quantum efficiency, either 1 or 2 bytes per pixel * The pixels are either 1 or 2 bytes per pixel dependent on the compression mode. Uncompressed, 12-bit images require 2 bytes per pixel, while compressed 8-bit images require 1 byte per pixel. For the uncompressed, 12-bit data, each row contains 1046 'pixels' of data, which is exactly 2092 bytes. This is 2 bytes for the sync, 2 bytes for the line counter, 8 pixels at 2 bytes per pixel, 1024 pixels at 2 bytes per pixel and, finally, 12 pixels at 2 bytes per pixel. In equation form: bytes_per_uncompressed_line : 2 + 2 + 2 * ( 8 + 1024 + 12 ) : 2092 For the compressed, 8-bit data, each row contains 1048 'pixels' of data, which is exactly 1048 bytes. This is 2 bytes for the sync, 2 bytes for the line counter, 8 pixels at 1 byte per pixel, 1024 pixels at 1 bytes per pixel and, finally, 12 pixels at 1 bytes per pixel. In equation form: bytes_per_compressed_line : 2 + 2 + 1 * ( 8 + 1024 + 12 ) : 1048 Reading with RAW image readers: : When using any of the supported PDS readers, this extra data at the beginning and end of the line is not displayed, but when reading these images with a raw raster-scan style reader, this extra data at the beginning and ending of each line must be taken into account. Values to use when reading images with a RAW readers: : Compression Mode # Rows # Columns Data Type ----------------- ------ --------- ------------------------------ Compressed 1024 1048 BYTE data Uncompressed 1024 1046 MSB_Unsigned_integer (16-bit) Finding the offset to the data within the file: : When trying to read the histogram or image arrays from the file using a RAW reader, the reader must first skip all of the information before the object to be read. As an example, to read the image object using a raw reader, the reader must first skip the PDS attached header, as well as the histrogram data. To determine the amount of data to skip, examine two keyword pairs from the attached label. To advance to the beginning of the histogram data, examine the following keywords: RECORD_BYTES : 2092 ^IMAGE_HISTOGRAM : 3 The first keyword defines the number of bytes within each record, while the second keyword indicates at which record the data begins. In this example, the data starts in record #3. This indicates that 2 other records contain data prior to the start of the histogram data. To compute the data offset, account for 2 records of data: in this example, the offset is (3-1)*2092 : 4184. To advance to the beginning of the image data, examine the following keywords: RECORD_BYTES : 2092 ^IMAGE : 11 As in the previous example, the first keyword defines the number of bytes within each record. The second keyword indicates the record at which the image data begins. To compute the data offset, follow the example above: Offset : ( ^image_histogram - 1 ) * record_bytes. Ex: Offset : ( 11 - 1) * 2092 : 20920 A Sample PDS Attached Image Label: : PDS_VERSION_ID : PDS3 /*** FILE FORMAT ***/ RECORD_TYPE : FIXED_LENGTH RECORD_BYTES : 2092 FILE_RECORDS : 1034 /*** POINTERS TO OBJECTS IN FILE ***/ ^IMAGE_HISTOGRAM : 3 ^IMAGE : 11 /*** GENERAL DATA DESCRIPTION PARAMETERS ***/ MISSION_NAME : STARDUST SPACECRAFT_NAME : STARDUST DATA_SET_ID : STARDUST-CAL-NC-2-PREFLIGHT-V1.0 OBSERVATION_NAME : CALIBRATION AT MINUS 30 DEGRESS C OBSERVATION_TYPE : -30 PRODUCT_ID : NC370034.IMG ORIGINAL_PRODUCT_ID : usd9898-144754.pds PRODUCER_INSTITUTION_NAME : JPL/ACT PRODUCT_TYPE : EDR SOFTWARE_NAME : ACT DMAPKTDECOM 1.0 MISSION_PHASE_NAME : PREFLIGHT CALIBRATION TARGET_NAME : CALIMG FRAME_SEQUENCE_NUMBER : 34 /*** TIME PARAMETERS ***/ START_TIME : 1998-04-08T14:47:54 STOP_TIME : N/A PRODUCT_CREATION_TIME : 2000-02-25T02:06:51 /*** CAMERA RELATED PARAMETERS ***/ INSTRUMENT_NAME : NAVIGATION CAMERA INSTRUMENT_ID : NC EXPOSURE_DURATION : 0.020 CAL_LAMP_MODE_ID : OFF QUANTIZATION_MODE_ID : OFF FILTER_NUMBER : 7 FILTER_NAME : HiRes CENTER_FILTER_WAVELENGTH : 596.4 FILTER_FWHM : 200.0 /*** CALIBRATION EQUIPMENT PARAMETERS ***/ MEASUREMENT_SOURCE_DESC : KEITHLY 607 ELECTROMETER RADIANCE : 0.981 /*** TEMPERATURE PARAMETERS IN ***/ INSTRUMENT_TEMPERATURE : 306.95 FOCAL_PLANE_TEMPERATURE : 243.15 /*** DESCRIPTION OF OBJECTS CONTAINED IN THE FILE ***/ OBJECT : IMAGE_HISTOGRAM ITEMS : 4096 DATA_TYPE : MSB_UNSIGNED_INTEGER ITEM_BITS : 32 END_OBJECT : IMAGE_HISTOGRAM OBJECT : IMAGE LINES : 1024 LINE_SAMPLES : 1024 SAMPLE_TYPE : MSB_UNSIGNED_INTEGER SAMPLE_BITS : 16 SAMPLE_BIT_MASK : 2#0000111111111111# MAXIMUM : 3063 MINIMUM : 603 LINE_PREFIX_BYTES : 20 LINE_SUFFIX_BYTES : 24 MEAN : 859.588 STANDARD_DEVIATION : 64.9859 SATURATED_PIXELS : 0 CHECKSUM : 50501490 END_OBJECT : IMAGE END General notes regarding label: : * Strings appear in quotes. * Integers and PDS Times do not take quotes. * Lists are enclosed within {} type brackets. * If a field is unknown, UNK may be entered. * If a field is not applicable, N/A may be entered. * Fields can spill freely, with or without white space, onto following lines. Definition of Keywords/Values from the PDS Data Dictionary: : PDS_VERSION_ID The pds_version_id keyword indicates the version number of the PDS standards documents that is valid when a data product label is created. Values for the PDS_VERSION_ID are formed by appending the integer for the latest version number to the letters 'PDS'. Examples: PDS3, PDS4. RECORD_TYPE The record_type keyword indicates the record format of a file. Note: In the PDS, when record_type is used in a detached label file it always describes its corresponding detached data file, not the label file itself. The use of record_type along with other file-related data elements is fully described in the PDS Standards Reference. RECORD_BYTES The record_bytes keyword indicates the number of bytes in a physical file record, including record terminators and separators. FILE_RECORDS The file_records keyword indicates the number of physical file records, including both label records and data records. ^IMAGE_HISTOGRAM The image_histogram object represents a pointer to the image histogram. The value is in RECORD_BYTE units and indicates that the data starts at the beginning of the record mentioned. As an example, if the pointer value is 4, then the 3 records are populated with other data. If the bytes per record is 2092, the image histogram data starts at byte 6276 ^IMAGE The ^image pointer represents a byte offset to the image data. The value is in RECORD_BYTE units. As an example, if the pointer value is 11, and the bytes per record is 2092, the image histogram data starts at byte 20920. MISSION_NAME The mission_name element identifies a major planetary mission or project. A given planetary mission may be associated with one or more spacecraft. SPACECRAFT_NAME The spacecraft_name element provides the full, unabbreviated name of a spacecraft. DATA_SET_ID The data_set_id element is a unique alphanumeric identifier for a data set or a data product. The data_set_id value for a given data set or product is constructed according to flight project naming conventions. In most cases the data_set_id is an abbreviation of the data_set_name. Example value: STARDUST-CAL-NC-2-PREFLIGHT-V1.0. Note: In the PDS, the values for both data_set_id and data_set_name are constructed according to standards outlined in the Standards Reference. OBSERVATION_NAME The observation_name element provides the identifier for an observation or sequence of commands. For this dataset, this keyword has 3 possibilities, based on the day the calibration was completed: 4/08/98 CALIBRATION AT MINUS 30 DEGRESS C 4/09/98 CALIBRATION AT MINUS 40 DEGRESS C 4/10/98 CALIBRATION AT MINUS 50 DEGRESS C OBSERVATION_TYPE The observation_type element identifies the general type of an observation. This keyword has 3 possibilities, based on the day the calibration was completed: 4/08/98 -30 4/09/98 -40 4/10/98 -50 PRODUCT_ID The product_id data element represents a permanent, unique identifier assigned to a data product by its producer. Note: In the PDS, the value assigned to product_id must be unique within its data set. This value represents the actual name of the image file on the archive. The output directory is also available. ORIGINAL_PRODUCT_ID The original_product_id element provides the temporary product identifier that was assigned to a product during active flight operations which was eventually replaced by a permanent id (see product_id). In this dataset, this value represents the original filename recorded by the calibration equipment. This name can be linked back to the original calibration log files. PRODUCER_INSTITUTION_NAME The producer_institution_name element identifies a university, research center, NASA center or other institution associated with the production of a data set. This would generally be an institution associated with the element producer_full_name. In this dataset, this field has the value of JPL/ACT, described as: JPL : Jet Propulsion Laboratory. ACT : Applied Coherent Technology Corp. PRODUCT_TYPE The product_type data element identifies the type or category of a data product within a data set. Examples: EDR, UDR. SOFTWARE_NAME The software_name element identifies data processing software such as a program or a program library. MISSION_PHASE_NAME The mission_phase_name element provides the commonly-used identifier of a mission phase. TARGET_NAME The target_name element identifies a target. The target may be a planet, satellite, ring, region, feature, asteroid or comet. See target_type. In this calibration dataset, the target is CALIMG. FRAME_SEQUENCE_NUMBER The frame_sequence_number element indicates the location within a cycle at which a specific frame occurs. Frames are repeated in a specific order within each cycle. In this dataset, this value represents a uniquly sequential identifier assigned to each image of the archive. START_TIME The start_time element provides the date and time of the beginning of an event or observation (whether it be a spacecraft, ground-based, or system event) in UTC system format. Formation rule: YYYY-MM-DDThh:mm:ss. STOP_TIME The stop_time element provides the date and time of the end of an observation or event (whether it be a spacecraft, ground-based, or system event) in UTC system format. Formation rule: YYYY-MM-DDThh:mm:ss. PRODUCT_CREATION_TIME The product_creation_time element defines the UTC system format time when a product was created. Formation rule: YYYY-MM-DDThh:mm:ss. INSTRUMENT_NAME The instrument_name element provides the full name of an instrument. Note: that the associated instrument_id element provides an abbreviated name or acronym for the instrument. INSTRUMENT_HOST_NAME The instrument_host_name element provides the full name of the host on which an instrument is based. This host can be either a spacecraft or an earth base. Thus, the instrument_host_name element can contain values which are either spacecraft_name values or earth_base_name values. INSTRUMENT_ID The instrument_id element provides an abbreviated name or acronym which identifies an instrument. Note: The instrument_id is not a unique identifier for a given instrument. Note also that the associated instrument_name element provides the full name of the instrument. EXPOSURE_DURATION The exposure_duration element provides the value of the time interval between the opening and closing of an instrument aperture (such as a camera shutter). CAL_LAMP_MODE_ID The cal_lam_mode_id element provides the value of the calibration lamp mode at the time the image was acquired. This value indicates whether the calibration lamp was on or off at the time the image was acquired. QUANTIZATION_MODE_ID The quantization_mode_id element provides the identifier for the quantization mode used when the image was acquired. This value indicates if the original data was quantized at the time the data was acquired. A value of OFF indicates that the data was not quantized, while a value of ON indicates that the data was quantized. In this dataset, this value indicates that the image was compressed with a hardware square-root compression technique prior to transmission. FILTER_NUMBER The filter_number element provides the number of an instrument filter through which an image or measurement was acquired or which is associated with a given instrument mode. Note: that the filter_number is unique, while the filter_name is not. FILTER_NAME The filter_name element provides the commonly- used name of the instrument filter through which an image or measurement was acquired or which is associated with a given instrument mode. Example values: RED, GREEN. See also filter_number. CENTER_FILTER_WAVELENGTH The center_filter_wavelength element provides the mid_point wavelength value between the minimum and maximum instrument filter wavelength values. FILTER_FWHM The filter_fwhm element provides the measurement for the Full-width, half-max value associated with the filter. This is the width of the filter transmission curve at the point of half of the maximum transmission value. MEASUREMENT_SOURCE_DESC The measurement_source_desc element describes the source of light used in a laboratory-generated data set, or the radar transmitter in the case of radar astronomy experiments. RADIANCE The radiance element describes the amount of current recorded from the photo-diode detector used to measure the radiance output from the source emitter. INSTRUMENT_TEMPERATURE The instrument_temperature element provides the temperature, in degrees Celcius, of an instrument or some part of an instrument. FOCAL_PLANE_TEMPERATURE The focal_plane_temperature element provides the temperature of the focal plane array in degrees kelvin at the time the observation was made. OBJECT : IMAGE_HISTOGRAM The histogram object is a sequence of numeric values that provides the number of occurrences of a data value or a range of data values in a data object. The number of items in a histogram will normally be equal to the number of distinct values allowed in a field of the data object. (For example, an 8-bit integer field can have 256 values. This would result in a 256-item histogram.) Histograms may be used to bin data, in which case an offset and scaling factor indicate the dynamic range of the data represented. The following equation allows the calculation of the range of each 'bin' in the histogram. 'bin lower boundary' : ('bin element' * scaling_factor) + offset. ITEMS The items element defines the number of multiple, identical occurrences of an single object, such as a column. See also: repetitions. Note: In the PDS, the data element ITEMS is used for multiple occurrences of a single object, such as a column. REPETITIONS is used for multiple occurrences of a repeating group of objects, such as a container. For a fuller description of the use of these data elements, please refer to the Standards Reference. DATA_TYPE The data_type element supplies the internal representation and/or mathematical properties of a value being stored. See also: bit_data_type, general_data_type. Note: In the PDS, users may find a bit-level description of each data type in the Standards Reference document. ITEM_BITS The item_bits element indicates the number of bits allocated for a particular bit data item. Note: In the PDS, the item_bits element is used when the items element specifies multiple occurrences of an implied item within a BIT_COLUMN object definition. END_OBJECT The end_object element terminates the object description. OBJECT : IMAGE A regular array of sample values. Image objects are normally processed with special display tools to produce a visual representation of the sample values. This is done by assigning brightness levels or display colors to the various sample values. Images are composed of LINES and SAMPLES. They may contain multiple bands, in one of several storage orders. Note: Additional engineering values may be prepended or appended to each LINE of an image, and are stored as concatenated TABLE objects, which must be named LINE_PREFIX and LINE_SUFFIX. IMAGE objects may be associated with other objects, including HISTOGRAMs, PALETTEs, HISTORY, and TABLEs which contain statistics, display parameters, engineering values, or other ancillary data. LINES The lines element indicates the total number of data instances along the vertical axis of an image. Note: In PDS label convention, the number of lines is stored in a 32-bit integer field. The minimum value of 0 indicates no data received. LINE_SAMPLES The line_samples element indicates the total number of data instances along the horizontal axis of an image. SAMPLE_TYPE The sample_type element indicates the data storage representation of sample value. SAMPLE_BITS The sample_bits element indicates the stored number of bits, or units of binary information, contained in a line_sample value. SAMPLE_BIT_MASK The sample_bit_mask element identifies the active bits in a sample. Note: In the PDS, the domain of sample_bit_mask is dependent upon the currently-described value in the sample_bits element and only applies to integer values. For an 8-bit sample where all bits are active the sample_bit_mask would be 2#11111111#. MAXIMUM The maximum element indicates the largest value occurring in a given instance of the data object. MINIMUM The minimum element indicates the smallest value occurring in a given instance of the data object. LINE_PREFIX_BYTES The line_prefix_bytes element indicates the number of non-image bytes at the beginning of each line. The value must represent an integral number of bytes. LINE_SUFFIX_BYTES The line_suffix_bytes element indicates the number of non-image bytes at the end of each line. This value must be an integral number of bytes. MEAN The mean element provides the average of the DN values in the image array. STANDARD_DEVIATION The standard_deviation element provides the standard deviation of the DN values in the image array. SATURATED_PIXELS The saturated_pixels element provides a count of the number of pixels in the array which at the maximum DN value. For this dataset, the non-quantized data has a maximum value of 4095, while the quantized data has a maximum value of 255. CHECKSUM The checksum element represents an unsigned 32-bit sum of all data values in a data object. END End of the PDS Label. Contact Information: : For any questions regarding the data format of the archive, contact: Howard Taylor Applied Coherent Technology Corp 112 Elden Street, Suite K Herndon, VA 20170 (818) 354-5401 taylor@actgate.com
DATA_SET_RELEASE_DATE 2000-03-17T00:00:00.000Z
START_TIME 1998-04-08T12:00:00.000Z
STOP_TIME 1998-04-10T12:00:00.000Z
MISSION_NAME STARDUST
MISSION_START_DATE 1999-02-07T12:00:00.000Z
MISSION_STOP_DATE 2006-01-16T12:00:00.000Z
TARGET_NAME CALIMG
TARGET_TYPE CALIBRATION
INSTRUMENT_HOST_ID SDU
INSTRUMENT_NAME NAVIGATION CAMERA
INSTRUMENT_ID NAVCAM
INSTRUMENT_TYPE IMAGING CAMERA
NODE_NAME Small Bodies
ARCHIVE_STATUS SAFED
CONFIDENCE_LEVEL_NOTE The data collected here has been prepared with the highest concern for the perfectness of the data delivered. During the processing of the image data in preparation for delivery with this volume, the structure of each image was verified. This verification included detection of both the sync word and the line count bytes at the beginning of each line. The data that was used to produce this archive was generated the by the Ground Support Equipment (GSE) and was found to differ from the general format of the flight image data. The flight data is organized as described above: each row includes a sync pattern, line counter, BLS pixels, image data and finally the overclock pixels. The GSE produced data that was
CITATION_DESCRIPTION Unknown
ABSTRACT_TEXT This data set contains the results of the preflight calibration of the Stardust Navigation Camera. The images were collected in an attempt to mimic the environment that the camera would experience during cruise and encounter with the comet Wild-2. These data are saved for historical reasons. They are not considered to be of archival quality.
PRODUCER_FULL_NAME APPLIED COHERENT TECHNOLOGY CORPORATION
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