Data Set Information
DATA_SET_NAME NEAR MSI IMAGES FOR EROS/ORBIT
DATA_SET_ID NEAR-A-MSI-3-EDR-EROS/ORBIT-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview:NEAR EDR volume sets contain a single data set, from one instrumentand one mission phase (defined in the phase table in /AAREADME.TXT). The first volume of the set is a documentation-only volume and containsCALIB, GEOMETRY and other non-data subdirectories. The INDEX directoryon the first volume contains the summary of all the volumes. The DOCUMENTdirectory on the first volume contains non-changing documentation.Subsequent volumes contain only BROWSE, CATALOG, DATA, and INDEXsubdirectories in order to minimize duplication. The data volumes alsocontain a DOCUMENT directory, which contains information related to thecalibration of the data files on that volume. Directory/Product Description:------------------------------All images and image products described below are 537 x 244rectangular pixels where the rectangular pixel dimensions are162 x 96 microradians. RAW: Raw images. Image in this directory are units of raw DN, asreceived from the spacecraft after data were uncompressed. No editingof the data has taken place. Missing transfer frames are representedas null pixels. RAD: Radiance images. Images in this directory have been calibratedto units of radiance using the following procedure. Dark current wasremoved using a model based on position in the image, mission-elapsedtime, exposure time, and CCD temperature. Frame transfer smear wasremoved using the procedure described in MSICAL.TXT. The image wasthen divided by the flat-field image corresponding to the filterthrough which the image was taken. To convert from these units of'corrected DN' to radiance, the image was divided by its exposuretime, a calibration coefficient (which converts from DNs/time toradiance) for that filter, and the temperature dependence of thecalibration coefficient as described in MSICAL.TXT. CRD: Cleaned radiance images. Images in this directory have beencalibrated to units of radiance using the following procedure. Darkcurrent, background frame transfer smear, and background leaked lightwere removed using the nominal image and one taken with a 0-msexposure within several seconds, through the same filter. The 0-msexposure has a slightly different dark current but the same frametransfer smear and leaked light. Dark current was removed separatelyfrom the two images, using a model based on position in the image,mission-elapsed time, exposure time, and CCD temperature. Thedark-corrected 0-ms image was subtracted from the dark-correctednominal image. The difference image was then divided by theflat- field image corresponding to the filter through which theimage was taken. To convert from these units of 'corrected DN' toto radiance, the image was divided by its exposure time, acalibration coefficient (which converts from DNs/time to radiance)for that filter, and the temperature dependence of the calibrationcoefficient as described in MSICAL.TXT. CRDDBL: Cleaned, deblurred radiance images. Images in this directoryhave been calibrated to units of radiance beginning with theprocedure described for cleaned radiance images (CRD). In addition,images were 'deblurred' by application of a Fourier filteringrestoration of a degraded image point-spread function, as describedin MSICAL.TXT. IOF: I/F images. Images in this directory have been calibrated tounits of I/F beginning with the procedure described for radianceimages (RAD). The images were subsequently divided by pi times thesolar irradiance expected at the target body's distance from the Sun. IOFDBL: Deblurred I/F images. Images in this directory have beencalibrated to units of I/F beginning with the procedure describedfor I/F images (IOF). In addition, images were 'deblurred' byapplication of a Fourier filtering resotration of a degreded imagepoint-spread funcition, as described in MSICAL.TXT CIF: Cleaned I/F images. Images in this directory have beencalibrated to units of I/F beginning with the procedure describedfor cleaned radiance images (CRD). The images were subsequentlydivided by pi times the solar irradiance expected at the targetbody's distance from the Sun. CIFDBL: Cleaned, deblurred I/F images. Images in this directoryhave been calibrated to units of radiance beginning with theprocedure described for cleaned I/F images (CIF). In addition,images were 'deblurred' by application of a Fourier filteringrestoration of a degraded image point-spread function, as describedin MSICAL.TXT. A note from SBN about dark frames and 0-ms exposures for MSI: ------------------------------------------------------------ For the Eros orbital phase of the archive, image frames as well as dark frames and 0-ms exposures have TARGET_NAME set to EROS in the raw data labels; processed dark exposures are also included in the calibrated data sets. This can cause confusion because the dark and 0-ms exposures are identified as Eros images yet appear to be ''bad'' exposures because of the idiosyncrasies of the MSI camera. Many MSI sequences were designed such that each image taken by the MSI camera was immediately followed by a 0-ms exposure to correct MSI camera idiosyncrasies. Also the camera was operated near room temperature so there was a significant amount of dark current generated during typical exposure durations. For this reason dark exposures of a duration equal to the usual exposure durations were often taken as a usual component of a sequence and, when viewed, appear to be nearly identical to the 0-ms exposures. Two methods of obtaining dark exposures were often used: (1) closing the shutter during the dark exposure or (2) opening the shutter during the exposure while pointing to ''dark sky''. It appears both techinques were used on several MSI sequences, such as ''seq9_30_xreg'' which was performed on day of year 2000-205. In this particular sequence, the first eight exposures (m0139720804f4 through m0139723433f4, including their associated 0-ms exposures) appear to have been done with the shutter closed, and then the next six exposures (m0139723596f4 through m0139724413f4) appear to have been done with the shutter opened, but with the MSI camera pointed away from the illuminated part of Eros by some small angle. The fifteenth exposure (m0139724574f4) appears to be the first exposure that picked up a small amount of the illuminated surface of Eros.------------------------------------------------------ Parameters:The definitions for the image parameters and other keywords are givenin the file MSIDEFINITIONS.TXT contained in the DOCUMENT/INSTRUMENTsubdirectory. Data:The data are in the form of FITS files with attached FITSheaders and detached PDS labels. Data files contain one imageper file. Ancillary Data:Geometry and CALIB subdirectories are described above. Media/Format:This data set is released as a CDROM set. Processing History:The processing history includes no background, noise, geometryor other corrections.
DATA_SET_RELEASE_DATE 2001-06-25T00:00:00.000Z
START_TIME 2000-01-11T12:00:00.000Z
STOP_TIME 2001-02-12T11:59:59.999Z
MISSION_NAME NEAR EARTH ASTEROID RENDEZVOUS
MISSION_START_DATE 1996-02-17T12:00:00.000Z
MISSION_STOP_DATE 2001-02-28T12:00:00.000Z
TARGET_NAME EROS
TARGET_TYPE ASTEROID
INSTRUMENT_HOST_ID NEAR
INSTRUMENT_NAME MULTI-SPECTRAL IMAGER
INSTRUMENT_ID MSI
INSTRUMENT_TYPE CAMERA
NODE_NAME Small Bodies
ARCHIVE_STATUS ARCHIVED
CONFIDENCE_LEVEL_NOTE Data Quality Flag:Each data file label includes a quality flag string in thedata_qualITY_ID keyword, extracted from the FITS keyword near-008 ofthe original data label. The fields of this keyword are defined below.Data quality defects flag is raised when there is missing data otherfields informational and not quality related. The eight characters ofthis field are described below. Definition - Data Quality Index c0 : Data Quality Flag (0:good,1:flagged for quality defects) c1 : Instrument Number for FC, CTP and AIU (1 or 2) c2 - c6 : Processing Flags not quality related c7 : CCDS Source (0:VC0, 1:VC1, 2:VC2, 3:VC3) Review:This data set was currently undergoing external peer review withinPDS in July, 2001.
CITATION_DESCRIPTION Murchie S., Taylor H., NEAR MSI IMAGES FOR EROS/ORBIT, NEAR-A-MSI-3-EDR-EROS/ORBIT-V1.0, NASA Planetary Data System, 2001.
ABSTRACT_TEXT This data set contains calibrated images of Eros taken in orbit by the NEAR Multi-Spectral Imager.
PRODUCER_FULL_NAME Howard W. Taylor
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