Data Set Information
DATA_SET_NAME DEEP IMPACT PREFLIGHT THERMAL-VACUUM 1 HRII DATA
DATA_SET_ID DIF-CAL-HRII-2-GROUND-TV1-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION This data set description was provided by Stephanie McLaughlin and Dennis Wellnitz (University of Maryland), who participated in the ground calibration tests of the Deep Impact instruments. Data Set Overview: This data set contains 2-dimensional spectral images acquired by the High Resolution Instrument's Infrared Spectrometer (HRII) during the the first preflight thermal-vacuum test (TV1) for Deep Impact. TV1 was considered a dry run in preparation for the full, second thermal-vacuum test (TV2) of the HRII instrument. The experiments performed during TV1 were designed by the Ball Aerospace team with input from the project's science team. TV1 was conducted by Don Hampton and Jeff Van Cleve of Ball Aerospace. Several science team members were present at all times to assist with the experiments and perform real-time analysis of the data. The main objectives of the TV1 were to: - Perform tests at the 3 nominal operating temperatures of optical bench: 128K, 135K, and 141K. - Determine best focus at 128K. - Measure the minimum and maximum wavelengths of the focal plane array (FPA). - Determine alignment of a spectral image on the FPA. - Determine the spatial and spectral dispersion of the FPA. - Obtain flat fields from various blackbody sources for preliminary measurements of the response of the FPA at different wavelengths. - Determine the non-linearity of the FPA. - Activate the internal stimulator to be used as an in-flight calibrator. - Check for stray light. To meet these objectives, the HRII was tested in the Ball 8 thermal-vacuum chamber; its shroud was cooled with liquid nitrogen and its instrument plate was cooled with liquid helium. The High Resolution telescope was simulated by an optical bench that was setup outside the chamber and oriented such that light produced by a source would enter the chamber's window and illuminate the FPA. Various types of emission, absorption, and black body sources were employed to test the FPA. Daily tests are summarized in the following chart. Since TV1 was a dry run, temperature logs were not created for the HRII's optical bench and FPA. Instead, these temperatures were simply recorded at the beginning of each test day. FPA IR Opt. Date/(DOY) Temp(K) Bench(K) Tests ---------- ------- ------- --------------------------------- 2002-06-27 120-113 155 First light on flight FPA with EM (178) electronics; CO2 and H20 asborp- tion lines visible; blackbody radiation of room visible at longer wavelengths. 2002-06-28 90-88 125-123 At colder temperatures, signal (179) visible across entire array; Check test telescope boresight; Tungsten source 2002-06-29 ~92 ~128 Focus test; Internal stimulator; (180) Argon source; Darks 2002-06-30 ~92 ~128 Best focus achieved; Argon and (181) Krypton sources; CO2 and H20 absorption lines; Darks; Various blackbody sources for flats 2002-07-01 ~99 ~135 Argon and Krypton sources; Darks; (182) Various blackbody sources for flats; Tungsten source 2002-07-02 ~105 ~141 Argon and Krypton sources; Darks; (183) Various blackbody sources for flats; M filter for long wave- length cutoff; Stray light; Internal stimulator For more information about the mission, the HRII instrument, and the anticipated HRII flight data, see A'Hearn, et al. (2005) [AHEARNETAL2005], Hampton, et al. (2005) [HAMPTONETAL2005], and Klaasen, et al. (2005) [KLAASENETAL2005]. Parameters: The image data are in units of raw data numbers. For TV1, all seven of the HRII's image modes were tested: Image MinExp X-Size Y-Size #Images Mode# (sec) (pix) (pix) Output Binning Comments ----- ------ ------ ------ ------- ------- ---------------------- 1 2.862 512 256 1 2x2 2 1.432 512 128 1 2x2 3 0.717 512 64 1 2x2 4 2.861 1024 512 1 1x1 5 2.865 512 256 1 2x2 6 1.432 1024 512 2 1x1 Reset then data frame 7 2.864 1024 512 1 1x1 Memory check mode In this table, MinExp is the frame-to-frame minimum exposure times, X-Size is spectral dimension and Y-Size is spatial dimension of the FPA. For all image modes except 6, the reset frame is automatically subtracted, on-chip, from the data frame and the result is output. For more information about the image modes, see Hampton, et al. (2005) [HAMPTONETAL2005]. Data: The data are in the form of FITS files with attached FITS headers and detached PDS labels. One data files contains one HRII 2-dimensional image. The fastest-varying axis (X) is the spectral dimension and slowest-varying axis (Y) is the spatial dimension along the spectrometer's slit. TV1 data filenames have this format: Iyymmdd_hhmmss_sss_xn.FIT where the 'yymmdd_hhmmss_sss' string the date, time and subseconds stamp provided by the ground-support computer when it stored the original data file. The clock on the ground-support computer was set to local Mountain time. The 'x' string' is valued with 'B' for HRII data and the 'n' string is only used for image mode 6 (see the last paragraph in this section). For TV1, the ground-support computer stored data files in a native image format, called 'IMG'. The raw data numbers were 14-bit and and left justified. A 100-byte image header was prepended to each data array. The 'IMG' data were converted to FITS at the Deep Impact Science Data Center (SDC) at Cornell University, using algorithms developed by Ball Aerospace for testing of the instruments and to allow real-time analysis of data during thermal-vacuum tests. During the conversion, raw data numbers were right justified to give the actual, true data numbers. Data in the 100-byte image header are captured in the FITS header. For HRII image mode 6, the ground-support computer stored a 3-dimensional data file: the first slice was the reset frame and the second slice was the data frame. To avoid mixing product types in this data archive for one instrument, the SDC split the reset and read frames into two separate files, with the reset frame receiving a filename suffix of '1' and the data frame receiving a suffix of '2'. This split was also required for TV2 HRII mode 6. However, by TV4, the ground-support computer was changed so that each read and data frame were written to separate 2-dimensional 'IMG' files. Also, HRII spectral images have reference rows and columns that border the edges on the image array. These areas are not exposed to light and are simply read out. The number of rows and columns varies between the types of image modes. .Ancillary Data: The DOCUMENT directory provides an image log recorded during TV1. The log contains an entry for each image acquired during TV1 and includes image parameters such as mode and experiment type. The log includes a brief description of each type of experiment performed during TV1 and a summary of experiments performed on each test date. The DOCUMENT directory also provides daily reports written by the test leaders and distributed to the test team and the science team. The reports describe in detail the test activities as well problems and successes encountered during TV1. The DOCUMENT directory includes the local PDS data dictionary used to produce the labels. Media/Format: This data set is released as a logical data volume.
DATA_SET_RELEASE_DATE 2004-10-15T00:00:00.000Z
START_TIME 2002-06-27T09:53:16.000Z
STOP_TIME 2002-07-02T01:52:14.000Z
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
TARGET_TYPE CALIBRATION
INSTRUMENT_HOST_ID DIF
INSTRUMENT_NAME DEEP IMPACT HIGH RESOLUTION INSTRUMENT - IR SPECTROMETER
INSTRUMENT_ID HRII
INSTRUMENT_TYPE INFRARED SPECTROMETER
NODE_NAME Small Bodies
ARCHIVE_STATUS ARCHIVED
CONFIDENCE_LEVEL_NOTE 1) The time stamp in the FITS filename can vary by several tens of seconds of the actual time the image was acquired. 2) TV1 was designed as a test run of the calibration procedures and processes to be used for the full thermal-vacuum test of the HRII instrument during August and September 2002 (called TV2). The data from TV1 have some noise because the FPA was only cooled to about 88K, the highest of the nominal operating temperatures for the instrument. Also, during TV1, existing procedures were refined as testing was performed. The Deep Impact science team and Ball Aerospace engineers used these data to perform only a preliminary calibration of the HRII instrument. These data were reviewed internally by the Deep Impact project before release to the planetary community. 3) Instrument temperatures were not rigorously recorded for TV1.
CITATION_DESCRIPTION Hampton, D.L., D.D. Wellnitz, and S.A. McLaughlin, DEEP IMPACT PREFLIGHT THERMAL-VACUUM 1 HRII DATA, DIF-CAL-HRII-2-GROUND-TV1-V1.0, NASA Planetary Data System, 2004.
ABSTRACT_TEXT This data set contains 2-dimensional spectral images acquired by the High Resolution Instrument's Infrared Spectrometer (HRII) during the the first preflight thermal-vacuum test (TV1) of the Deep Impact instruments.
PRODUCER_FULL_NAME STEPHANIE MCLAUGHLIN
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