Data Set Information
DATA_SET_NAME DEEP IMPACT 9P/TEMPEL ENCOUNTER - RAW ITS DATA V1.0
DATA_SET_ID DII-C-ITS-2-9P-ENCOUNTER-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview : This data set contains raw 9P/Tempel 1 and science calibration images acquired by the by the Deep Impact Impactor Targeting Sensor Visible CCD (ITS) during the 9P encounter phase of the mission. The 9P/Tempel 1 data are described in 'Deep Imact: The Anticipated Flight Data' by Klaasen, et al. (2005) [KLAASENTAL2005]. For more details about the images taken around impact, refer to the ITS encounter data summary document which provides a log of the exposures beginning after the release from the flyby craft until impact. The science calibration images are described in the 'Deep Impact In-Flight Calibration Summary' document and are also discussed in the 'Deep Impact: Anticipated Flight Data' paper by Klaasen, et al. (2005) [KLAASENETAL2005]. Calibration targets included the 16 Cyg A, Achernar, Beta Hyi, Canopus, Vega, HD 60753, HD 79447, NGC 3114, an internal calibration (stimulator) lamp, and dark frames. For a detailed discussion of how the instrument was calibrated, see 'Deep Impact Instrument Calibration' by Klaasen, et al. (2006) [KLAASENETAL2006]. A list of the comet and the science calibration observations in this data set is provided here: Mid-Obs Exposure IDs Date DOY Minimum Maximum Mission Activity ---------- --- ------- ------- -------------------------- 2005-05-06 126 4200012 4200015 Autonav Stray Light Test 2005-05-10 130 5040000 5040009 May Science Cal 5100000 5100017 May Science Cal 2005-05-11 131 5030000 5030004 May Science Cal 5050000 5050009 May Science Cal 5400000 5400001 May Science Cal 2005-05-13 133 5010000 5010004 May Science Cal 5020000 5020004 May Science Cal 5900000 5900004 May Science Cal 2005-06-07 158 6100000 6100017 June Science Cal 6900000 6900004 June Science Cal 2005-06-08 159 6040000 6040009 June Science Cal 6400000 6400001 June Science Cal 2005-06-09 160 6010000 6010004 June Science Cal 6030000 6030001 June Science Cal 6050000 6050009 June Science Cal 2005-06-10 161 6020000 6020004 June Science Cal 2005-07-03 184 9000026 9000043 Release, Continuous Comet Imaging 2005-07-03 184 9000046 9000059 Pre-Impact Stim and Dark Cal 2005-07-03 184 9000060 9000128 Continuous Comet Imaging 2005-07-04 185 9000130 9000710 Continuous Comet Imaging, Impact Essential Reading ----------------- The following documents, located on the Deep Impact Documentation volume, DIDOC_0001, are essential for the understanding and interpretation of this data set: ANTICIPATED_FLIGHT_DATA.* : Anticipated flight data by Klaasen, et al. (2005) [KLAASENTAL2005] ITS_ENCOUNTER_DATA_SUMMARY.* : Image log from 28 hours before impact through lookback INFLIGHT_CALIBRATION_SUMMARY.* : Summary of in-flight calibrations CALIBRATION_DOC.* : Instrument calibration by Klaasen, et al. (2006) [KLAASENETAL2006] INSTRUMENTS_HAMPTON.* : Instrument paper by Hampton, et al. (2005) [HAMPTONETAL2005] MISSION_OVERVIEW_AHEARN.* : Mission overview by A'Hearn, et al. (2005) [AHEARNETAL2005B] SCLK_CORRELATION.* : Discussion of the discrepancy between the spacecraft clocks and UTC AIDC_FLIGHT_HRIV_MRI_ITS.* : Description of the data set and definitions of label keywords Related Data Sets ----------------- The following PDS data sets are related to this one: DII-CAL-ITS-2-9P-CRUISE-V1.0 : Raw ITS cruise calibrations DII-C-MRI-3/4-9P-ENCOUNTER-V1.0 : Reduced ITS encounter data DII-CAL-ITS-2-GROUND-TV3-V1.0 : ITS pre-flight calibrations DI-C-SPICE-6-V1.0 : SPICE kernels Processing : The uncompressed and compressed FITS images in this data set were created by the Deep Impact Science Data Center (SDC) at Cornell University and were assembled from raw telemetry packets sent down by the flyby spacecraft. Information from the embedded spacecraft header (the first 100 bytes of an uncompressed or 50 bytes of a compressed image) was extracted and stored in the primary FITS header. Geometric parameters were computed using the best available SPICE kernels and the results were also stored in the FITS header. If telemetry packets were missing, the corresponding pixels were flagged as missing in the quality map included as a FITS 'IMAGE' extension. The image quality map was described in the calibration pipeline section of the 'Deep Impact Instrument Calibration' paper by Klaasen, et al. (2006) [KLAASENETAL2006]. The SDC did not apply any type of correction or decompression algorithm to the raw data. Applied Coherent Technology Corporation in Herndon, VA, produced the PDS data labels by extracting parameters from the FITS headers. Data : CCD Images ---------- The two-dimensional, visible CCD images in this data set are in FITS format. The primary data array contains the CCD image and is followed by an image extension that contains a pixel-by-pixel quality map. Each FITS file is accompanied by a detached PDS label. Compression ----------- This data set contains compressed and uncompressed raw FITS images, that is, data as they were received on the ground. Data compression was performed on board the spacecraft using a set of four lossy lookup tables. A compressed FITS image consisted of 14-bit values compressed and stored as a one-byte pixel. An uncompressed FITS image consisted of 14-bit pixels stored as two bytes. The COMPRESSED_IMAGE_VALUE in the data label indicates if an raw image is compressed or uncompressed. The COMPRESSOR_ID identifies the lookup table that was used to compress an image. The calibration pipeline decompressed raw images. For information about data compression, refer to 'An Overview of the Instrument Suite for the Deep Impact Mission' by Hampton, et al. (2005) [HAMPTONETAL2005] or the instrument calibration paper by Klaasen, et al. (2006) [KLAASENETAL2006]. Target Name and Description --------------------------- The TARGET_NAME keyword in the data labels was set to the intended target, either '9P/Tempel 1' or 'Calibration'. The TARGET_DESC keyword provides the name of the specific calibration target, such as 'Dark'. True-Sky ''As Seen By Observer'' Display ---------------------------------------- A true-sky view is achieved by displaying the image using the standard FITS convention: the fastest-varying axis (samples) increasing to the right in the display window and the slowest- varying axis increasing to the top. This convention is also defined in the image labels: SAMPLE_DISPLAY_DIRECTION : 'RIGHT' LINE_DISPLAY_DIRECTION : 'UP' This topic is discussed in detail in the 'Quadrant Nomenclature' section of the 'Deep Impact Instrument Calibration' document. The direction to Celestial North and Ecliptic North, measured clockwise from the top of the displayed image, is provided in PDS labels by CELESTIAL_NORTH_CLOCK_ANGLE and SOLAR_NORTH_POLE_CLOCK_ANGLE, both of which assume the correct display defined by SAMPLE_DISPLAY_DIRECTION and LINE_DISPLAY_DIRECTION. File Naming Convention ---------------------- The naming convention for the data labels and FITS files is IVcccccccccc_eeeeeee_nnn.LBL or FIT where cccccccccc is the spacecraft clock count at the mid-point of the observation, eeeeeee is the exposure ID (OBSERVATION_ID in data labels). Up to 999 individual images could be commanded for one exposure ID. Therefore, nnn in the file name provides the sequentially increasing image number within an exposure ID corresponding to IMAGE_NUMBER in the data labels. For example, if two images were commanded for exposure ID 9000022, the two FITS files names would be IV0173709840_9000022_001.FIT and IV0173709840_9000022_002.FIT. Parameters : Data Units ---------- Raw image data are in units of raw data numbers. Imaging Modes ------------ For a description of the imaging modes, please see the Deep Impact instrument paper by Hampton, et al. (2005) [HAMPTONETAL2005]. Most image modes had a set of bias overclock rows and columns, located around the edges of the image array. All overclock pixels were excluded from the calculation of the values for MINIMUM, MAXIMUM, MEDIAN, and STANDARD_DEVIATION in the data labels. Time-Related Keywords --------------------- All time-related keywords in the data labels, except EARTH_RECEIVED_TIME, are based on the clock on board the flyby spacecraft. EARTH_RECEIVED_TIME provides the UTC when an Earth-based observer should be able to see an event recorded by the instrument. The TIME_FROM_IMPACT_VALUE keyword in the data labels was based on the estimated impact time at the flyby spacecraft of UTC 05:44:35.821 on 4 Jul 2005. Geometry-Related Keywords ------------------------- The SDC attempted to calculate geometric parameters relating to the target only when it was within several fields of view of the instrument boresight. When these parameters could not be calculated, the corresponding keywords in the PDS data labels were set to a value of unknown (UNK). Also, geometry-related keywords for calibration targets such as Canopus were set to UNK. Geometry-related parameters in the PDS data labels are uncertain at a level of a few seconds because of a known 2-second discrepancy between the clocks on board the flyby and impactor spacecraft and between in-situ data and ground-based observations. The Deep Impact project generated self-consistent SPICE kernels, outside of NAIF, to help account for the discrepancy. The November 2005 version of these kernels was used to calculate the image times and geometric information in PDS data labels. After further analysis of the timing problem in early 2006, improved self-consistent SPICE kernels were generated by the Deep Impact project. These kernels are included in the DI SPICE data set. For more information about this discrepancy, please see the spacecraft clock correlation document included on the Deep Impact document volume. Ancillary Data : Geometric parameters included in the data labels were computed using the November 2005 version of the SPICE data. These were the best available data at the time of image creation. Since image creation, some SPICE data have been improved, and these are archived in the Deep Impact SPICE data set. Coordinate System : Earth Mean Equator and Vernal Equinox of J2000 (EME J2000) was the inertial reference system used to specify observational geometry parameters in the data labels. Geometric parameters provided in the data labels were computed at the epoch specified by MID_IMAGE_TIME, except for the target-to-sun and earth-observer-to-target parameters. Target-to-sun values were calculated for the time when the light left the sun while earth-observer-to-target were calculated for the time when the light left the target.
DATA_SET_RELEASE_DATE 2005-12-31T00:00:00.000Z
START_TIME 2005-05-06T07:12:45.682Z
STOP_TIME 2005-07-04T05:44:31.357Z
MISSION_NAME DEEP IMPACT
MISSION_START_DATE 2005-01-12T12:00:00.000Z
MISSION_STOP_DATE 2005-07-13T12:00:00.000Z
TARGET_NAME CALIBRATION
9P/TEMPEL 1 (1867 G1)
TARGET_TYPE CALIBRATION
COMET
INSTRUMENT_HOST_ID DII
INSTRUMENT_NAME DEEP IMPACT IMPACTOR TARGETING SENSOR - VISIBLE CCD
INSTRUMENT_ID ITS
INSTRUMENT_TYPE CCD CAMERA
NODE_NAME Small Bodies
ARCHIVE_STATUS ARCHIVED
CONFIDENCE_LEVEL_NOTE Confidence Level Overview : As noted above, the geometry-related parameters in the PDS data labels are uncertain at a level of a few seconds because of a known 2-second discrepancy between the clocks on board the flyby and impactor spacecraft and between in-situ data and ground-based observations. For more information about this discrepancy, please see the spacecraft clock correlation document included on the Deep Impact document volume. The FITS files in this data set were reviewed internally by the Deep Impact project and were used extensively by the science team to calibrate the instruments. Review : This data set passed a PDS peer review that took place on April 5, 2006. Reviewers stated these data should be archived pending resolution of the liens produced during the review. Data Coverage and Quality : All expected data were received on the ground and are included in this data set. Horizontal striping through some images indicates missing data. The image quality map extension identifies where pixels are missing. If the second most-significant bit of a pixel in the image quality map is turned on, then data for the corresponding image pixel is missing. For more information, refer to the notes about image quality map in the PDS data label or to the 'Deep Impact Instrument Calibration' paper. Limitations : Displaying Images ----------------- Flight software overwrote the first 50 uncompressed (or 100 compressed) pixels of first quadrant read out from the instrument with an image header. These original header pixels were included in the raw FITS images. Since the values in these pixels vary dramatically, it recommended that the values of the MINIMUM and MAXIMUM keywords in the PDS data label (or the MINPVAL and MAXPVAL in the FITS header) be used to scale an image for display because these values exclude the header bytes as well as the overclock rows and columns located around the edge of the image. The location of the header bytes in a FITS image depends on the readout order of the instrument, as discussed in the quadrant nomenclature section of the 'Deep Impact Instrument Calibration' paper.
CITATION_DESCRIPTION McLaughlin, S. A., B. Carcich, T. McCarthy, M. Desnoyer, and K.P. Klaasen, DEEP IMPACT 9P/TEMPEL ENCOUNTER - RAW ITS DATA V1.0, DII-C-ITS-2-9P-ENCOUNTER-V1.0, NASA Planetary Data System, 2005.
ABSTRACT_TEXT This data set contains raw 9P/Tempel 1 and science calibration images acquired by the Deep Impact Impactor Targeting Sensor Visible CCD during the 9P encounter phase of the mission.
PRODUCER_FULL_NAME STEPHANIE MCLAUGHLIN
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