Data Set Information
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| DATA_SET_NAME |
IUE SWP DATA OF COMET SL9/JUPITER/IMPACT SITES
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| DATA_SET_ID |
IUE-J-SWP-3-EDR-SL9-V1.0
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| NSSDC_DATA_SET_ID |
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| DATA_SET_TERSE_DESCRIPTION |
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| DATA_SET_DESCRIPTION |
Data Set Overview : Raw Image Data and Label Parameters ----------------------------------- Each raw image consists of an array of 8-bit picture elements or 'pixels'. Each vidicon scan line consists of 768 pixels or 'samples' obtained in minor frame units of 96 pixels; 768 such scan lines compose the entire image. Line 1, sample 1 is at the upper left corner of the image; line 768, sample 768 is at the lower right corner of the image. Each raw pixel value lies in the range 0 to 255 (integers only). The units of raw pixel values are data numbers (DN), which are proportional (up to the telemetry system limit of 255) to the integrated charge read out from the SEC Vidicon target in the camera scanning process. Since the telemetry system saturates at 255, the DN/charge proportionality breaks down at that level. Associated with each raw image is a set of 20 header, or label, records. Each record is 360 8-bit bytes long (a concatenation of five 72-byte logical records). This set of 20 label records is generated by the Operations Control Center (OCC) software during image acquisition and contains various identifying parameters and scientific/engineering data pertinent to the image. Raw images must be corrected for the instrumental effects of the SEC Vidicon camera system before quantitatively meaningful data can be extracted from them. The methods of compensation for the radiometric (photometric) non-linearities and non-uniformities and the geometric distortion introduced by the vidicon system are described in the NEWSIPS Manual, Chapters 5 - 8 (Nichols-Bohlin et al., 1993 [NICHOLS-BOHETAL1993]). In addition, figures 2.1-15 of the same manual illustrate schematically the spectral formats in both dispersion modes, for both apertures and for all operational cameras. IUE Final Archive Data Products for SL9/Jupiter Events ------------------------------------------------------ The output files for the Final Archive are fundamentally different in content, quantity, size, and format from those of the current reduction package (IUESIPS). A brief description of each file is given below along with a definition of the associated FITS format. All output data from the Final Archive were translated from FITS format. The Table below lists the output files that are available only for low-dispersion data. All output data from the SL9/Jupiter Archive were translated from FITS format using a program developed at the PDS - Small Bodies Node (described in the file IUE_DOC). --------------------------------------------------------------------- * IUE File Naming Conventions * Resampled Image (SILO) * Resampled Flag Image (SFLO) * Extracted Low-Dispersion Spectra (MXLO) --------------------------------------------------------------------- IUE File Naming Conventions --------------------------- The file names are defined so as to allow the unique identification of the information stored in the file. The IUE file name is formed by the concatenation of the following codes: * Camera: 3 letter code (SWP). * Image number: 5 digits. * File type: 2 letter code as: RI raw image VD vector displacement XC cross correlation coefficients (binary table extension of the VD file) LI linearized image LF flags associated with the linearized image (image extension of the LI file) SI resampled image SF flags associated with the resampled image (image extension of the SI file) SW wavelengths associated with the high-dispersion resampled image MX merged extracted spectrum (large, small or both apertures) WH whole high-dispersion extracted spectrum * Dispersion: 2 letter code (HI, LO). Resampled Image (SILO) ---------------------- The resampled image is a primary array produced by resampling the photometrically corrected portion of the LILO/LIHI image using the modified Shepard algorithm taken from the Numerical Algorithms Group (NAG) software package. Each pixel is resampled to the position determined by the summation of the vectors needed for: 1. shift to photometric correction (ITF) raw space, 2. shift from ITF space to geometrically-rectified space, 3. rotation such that orders are horizontal, 4. wavelength linearization, 5. detilting of large-aperture spectra for low-dispersion extended sources only, 6. alignment of the low-dispersion apertures for constant wavelength in the line direction, 7. adjustment so that both LW cameras provide coverage of the same spectral range, 8. adjustment to maintain the spectrum at approximately the same location in the file in the spatial direction (low dispersion only), 9. adjustment to SWP data to put the large-aperture data at the top of the file, 10. corrections for the spatial deviations (cross-dispersion wiggles) for the SWP and LWR low-dispersion data, 11. heliocentric velocity correction for high dispersion, 12. de-splaying correction for high-dispersion data, and 13. order centroiding for high-dispersion data. The resampled image (SILO) is I*2, in scaled FN units, with the one coordinate in pixels and the other coordinate in angstroms (A). Starting wavelength and wavelength increment are stored in the FITS header for low dispersion. Both large- and small-aperture data are present in one resampled image for low-dispersion data. The FITS header will indicate predicted line center for large-aperture and for small-aperture data. The SILO image is stored as a two-dimensional primary array consisting of pixels, while the SIHI is also pixels. Each pixel represents a flux number (FN) scaled by a factor of 32 for storage purposes. The pixels are coded as 16 bits, two's complement integers, with the bits stored in decreasing order of significance. The associated pixel quality flags are stored as an image extension which has the same dimensions as the primary array. Table 11.6 in the NEWSIPS Manual (Nichols-Bohlin et al., 1993 [NICHOLS-BOHETAL1993]) shows the basic FITS keywords for the main header and the image extension header. Resampled Flag Image (SFLO) --------------------------- This image extension is the same size as the resampled image. Like the linearized flag image, it contains the flag for specific error conditions for the corresponding pixel in the SILO/SIHI image. The values are stored as I*2. Extracted Low-Dispersion Spectra (MXLO) --------------------------------------- The extracted low-dispersion file uses the binary 3-D table extension with fixed-length floating point vectors to contain the extracted fluxes and associated data quality flags. Since no primary data are included, the extension header immediately follows the primary FITS header. Each row of the binary table includes the following columns: 1. Aperture designation as 'LARGE' or 'SMALL', stored in 5 ASCII characters. 2. Number of extracted points, one 16-bit integer. The number of extracted points is 640. 3. Starting wavelength, one single precision floating point value. 4. Wavelength increment, one single precision floating point value. 5. Net flux spectrum, array with 640 single precision floating point values. 6. Background flux spectrum, array with 640 single precision floating point values. 7. Sigma vector, array with 640 single precision floating point values. 8. Data quality flags, array of 640 16-bit integers. 9. Absolutely calibrated net flux spectrum, array with 640 single precision floating point values. Wavelengths are linearly sampled, and referenced to vacuum. Double aperture low-dispersion spectra will contain two rows in the above format, with one row for each aperture. Table 11.8 in the NEWSIPS Manual (Nichols-Bohlin et al., 1993 [NICHOLS-BOHETAL1993]) shows the basic FITS keywords for the MXLO file. Note: The keyword NAXIS1 in the table extension defines the number of bytes per row in the table.
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| DATA_SET_RELEASE_DATE |
1995-06-19T00:00:00.000Z
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| START_TIME |
1993-07-17T04:07:53.000Z
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| STOP_TIME |
1994-08-14T04:37:23.000Z
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| MISSION_NAME |
COMET SL9/JUPITER COLLISION
IUE
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| MISSION_START_DATE |
1993-01-01T12:00:00.000Z
1978-01-26T12:00:00.000Z
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| MISSION_STOP_DATE |
1996-01-01T12:00:00.000Z
1996-09-30T12:00:00.000Z
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| TARGET_NAME |
SL9
JUPITER
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| TARGET_TYPE |
COMET
PLANET
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| INSTRUMENT_HOST_ID |
IUE
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| INSTRUMENT_NAME |
SHORT-WAVELENGTH PRIME
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| INSTRUMENT_ID |
SWP
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| INSTRUMENT_TYPE |
SPECTROGRAPH
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| NODE_NAME |
Small Bodies
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| ARCHIVE_STATUS |
ARCHIVED
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| CONFIDENCE_LEVEL_NOTE |
N/A
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| CITATION_DESCRIPTION |
Grayzeck, E.J., and A.C. Raugh, IUE SWP DATA OF COMET SL9/JUPITER/IMPACT SITES, IUE-J-SWP-3-EDR-SL9-V1.0, NASA Planetary Data System, 1995.
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| ABSTRACT_TEXT |
This data set consists of: (a) Raw Image Data and Label Parameters - each raw image consists of an array of 8-bit picture elements or 'pixels'; (b) Associated with each raw image is a set of 20 header, or label records; (c) Raw images must be corrected for the instrumental effects of the SEC.
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| PRODUCER_FULL_NAME |
EDWIN J. GRAYZECK, JR
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| SEARCH/ACCESS DATA |
SBN Comet Website
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