Data Set Information
|
| DATA_SET_NAME |
DAWN VIR CAL (RDR) VESTA INFRARED SPECTRA V2.0
|
| DATA_SET_ID |
DAWN-A-VIR-3-RDR-IR-VESTA-SPECTRA-V2.0
|
| NSSDC_DATA_SET_ID |
|
| DATA_SET_TERSE_DESCRIPTION |
|
| DATA_SET_DESCRIPTION |
Data Set Overview : This data set contains the spectral radiance (W/(m**2*sr*micron)) data from the Dawn VIR instrument infrared channel for all Vesta encounter mission phases. The data cover the time period between 2011-05-03 and 2012-07-18. Changes in version 2 of this data set include: 1) Version 2 was produced using an improved calibration which removes artifacts in the 3-micron region. Contamination occuring in the 3-micron region during the HAMO and HAMO 2 phases is related to cold trapped volatiles and mimics a water vapor absorption. This contamination has not yet been effectively dealt with, thus that portion of the spectrum has been omitted from the data for the HAMO phases only. 2) Saturated data have been replaced with the CORE_HIGH_INSTR_SATURATION value. 3) The contaminated region in HAMO has been filled using the CORE_NULL value. 4) Corrections to some of the housekeeping (HK) data values. Note that Version 2.0 of the data set consists of version 3 data products (PRODUCT_VERSION_ID : 03; file names : *_3.*). The version 2 data products were not included in the PDS archive. Required Reading : The format of all VIR data are described in detail by the SIS document located in the /DOCUMENT directory. VIR team strongly recommends reading this documentation before using the data. In addition, there is a calibration procedure document that defines the data processing steps and the proper usage of the calibration files that are part of this data set. Update History : V1.0, 2014-Feb-27 - Initial release V2.0, 2017-Jul-21 - Improved calibration VIR Vesta Observations : The following table contains a listing of VIR observations at Vesta. ------------------------------------------------------------------------ Dawn Science Observations ------------------------------------------------------------------------ Start Mission Activity Activity Date Phase Name Description : 11-05-03 VSA APPROACH Vesta Science Approach Phase ------------------------------------------------------------------------ 11-05-10 VSA OPNAV_002 Ride-along cubes to FC OpNav images 11-06-08 VSA OPNAV_006 Ride-along cubes to FC OpNav images 11-06-14 VSA OPNAV_007 Ride-along cubes to FC OpNav images 11-06-30 VSA RC1 Ride-along cubes to FC rotational characterization movie #1 11-07-23 VSA OPNAV_019 Ride-along cubes to FC OpNav images 11-08-06 VSA C0Mosaic Ride-along cubes to FC mosaics images (equatorial and south) ------------------------------------------------------------------------ 11-08-11 VSS SURVEY Vesta Science Survey Phase (range ~3000 km) ------------------------------------------------------------------------ 11-08-11 VSS CYCLE1 Survey Cycle (orbit) 1 11-08-12 VSS CYCLE1 C1 Pushbroom observation 11-08-14 VSS CYCLE2 Survey Cycle (orbit) 2 11-08-14 VSS CYCLE2 C2 24 VIR VIS+IR cubes at 12 stations (North) 11-08-15 VSS CYCLE2 C2 24 VIR VIS+IR cubes at 12 stations (South) 11-08-17 VSS CYCLE3 Survey Cycle (orbit) 3 11-08-17 VSS CYCLE3 C3 Pushbroom observation 11-08-20 VSS CYCLE4 Survey Cycle (orbit) 4 11-08-20 VSS CYCLE4 C4 20 VIR VIS+IR cubes at 10 stations (North) 11-08-21 VSS CYCLE4 C4 20 VIR VIS+IR cubes at 10 stations (South) 11-08-23 VSS CYCLE5 Survey Cycle (orbit) 5 11-08-23 VSS CYCLE5 C5 24 VIR VIS+IR cubes at 12 stations (North) 11-08-24 VSS CYCLE5 C5 24 VIR VIS+IR cubes at 12 stations (South) 11-08-24 VSS CYCLE6 Survey Cycle (orbit) 6 11-08-25 VSS CYCLE6 C6 24 VIR VIS+IR cubes at 12 stations (Equator) 11-08-25 VSS CYCLE6 C6 24 VIR VIS+IR cubes at 12 stations (South) 11-08-28 VSS CYCLE7 Survey Cycle (orbit) 7 11-08-29 VSS CYCLE7 C7 16 VIR VIS+IR cubes at 8 stations (North) 11-08-29 VSS CYCLE7 C7 Pushbroom observation ------------------------------------------------------------------------ 11-09-03 VTH TRANSFER_ Vesta Transfer to HAMO Phase TO_HAMO ------------------------------------------------------------------------ 11-09-17 VTH OPNAV_003 Ride-along cubes to FC OpNav images 11-09-20 VTH BOUNUS_SCIENCE Bonus Science cubes 11-09-25 VTH FC1_CHECKOUT Ride-along cubes to FC1 checkout images ------------------------------------------------------------------------ 11-09-29 VSH HAMO Vesta Science HAMO Phase (avg rng ~950 km) ------------------------------------------------------------------------ 11-09-29 VSH CYCLE1 10 orbits of ride-along pushbroom to FC nadir imaging 11-10-06 VSH CYCLE2 9 orbits of ride-along pushbroom to FC off-nadir imaging 11-10-11 VSH CYCLE3 10 orbits of ride-along cubes and pushbroom to FC off-nadir imaging 11-10-16 VSH CYCLE4 10 orbits of ride-along cubes and pushbroom to FC off-nadir imaging 11-10-21 VSH CYCLE5 10 orbits of ride-along cubes and pushbroom to FC off-nadir imaging 11-10-26 VSH CYCLE6 10 orbits of ride-along pushbroom to FC nadir imaging ------------------------------------------------------------------------ 11-11-02 VTL TRANSFER_ Vesta Transfer to LAMO Phase TO_LAMO ------------------------------------------------------------------------ No VIR observations ------------------------------------------------------------------------ 11-12-12 VSL LAMO Vesta Science LAMO Phase (avg rng ~465 km) ------------------------------------------------------------------------ 11-12-13 VSL CYCLE1 VIR powered off 11-12-17 VSL CYCLE2 VIR powered off 11-12-24 VSL CYCLE3 VIR powered off 11-12-31 VSL CYCLE4 VIR powered off 12-01-07 VSL CYCLE5 7 orbits (2 VIS+IR 5 VIS-only) VIR full-slit pushbroom cubes 12-01-14 VSL CYCLE6 S/C safing - no FC or VIR data acquired 12-01-21 VSL CYCLE7 7 orbits (2 VIS+IR 5 VIS-only) VIR full-slit pushbroom cubes 12-01-28 VSL CYCLE8 7 orbits (2 VIS+IR 5 VIS-only) VIR full-slit pushbroom cubes 12-02-04 VSL CYCLE9 4 orbits (2 full slit 2 quarter slit) VIR VIS-IR pushbroom cubes 12-02-11 VSL CYCLE10 4 orbits (2 full slit 2 quarter slit) VIR VIS-IR pushbroom cubes 12-02-18 VSL CYCLE11 4 orbits (2 full slit 2 quarter slit) VIR VIS-IR pushbroom cubes 12-02-25 VSL CYCLE12 4 orbits (2 full slit 2 quarter slit) VIR VIS-IR pushbroom cubes 12-03-03 VSL CYCLE13 4 orbits (2 full slit 2 quarter slit) VIR VIS-IR pushbroom cubes 12-03-10 VSL CYCLE14 4 orbits (2 full slit 2 quarter slit) VIR VIS-IR pushbroom cubes 12-03-17 VSL CYCLE15 4 orbits (2 full slit 2 quarter slit) VIR VIS-IR pushbroom cubes 12-03-24 VSL CYCLE16 4 orbits (2 full slit 2 quarter slit) VIR VIS-IR pushbroom cubes 12-03-31 VSL CYCLE17 4 orbits (2 full slit 2 quarter slit) VIR VIS-IR pushbroom cubes 12-04-07 VSL CYCLE18 4 orbits (2 full slit 2 quarter slit) VIR VIS-IR pushbroom cubes 12-04-14 VSL CYCLE19 4 orbits (2 full slit 2 quarter slit) VIR VIS-IR pushbroom cubes 12-04-21 VSL CYCLE20 4 orbits (2 full slit 2 quarter slit) VIR VIS-IR pushbroom cubes 12-04-28 VSL CYCLE21 4 orbits (2 full slit 2 quarter slit) VIR VIS-IR pushbroom cubes ------------------------------------------------------------------------ 12-05-01 VT2 TRANSFER_ Vesta Transfer to HAMO-2 Phase TO_HAMO_2 ------------------------------------------------------------------------ No VIR observations ------------------------------------------------------------------------ 12-06-15 VH2 HAMO_2 Vesta Science HAMO Phase (avg rng ~950 km) ------------------------------------------------------------------------ 12-06-15 VH2 C0_OFFNADIR1 C0 10 orbits of VIR VIS+IR pushbroom cubes in the northern hemisphere and the south pole 12-06-20 VH2 C0_OFFNADIR2 C0 7 orbits of VIR VIS+IR pushbroom cubes in the northern hemisphere 12-06-24 VH2 CYCLE1 10 orbits of VIR VIS+IR pushbroom cubes in the southern hemisphere 12-06-29 VH2 CYCLE2 10 orbits of VIR VIS+IR pushbroom cubes in the southern hemisphere 12-07-04 VH2 CYCLE3 10 orbits of VIR VIS+IR pushbroom cubes in the equatorial region 12-07-09 VH2 CYCLE4 10 orbits of VIR VIS+IR pushbroom and scan-mirrorcubes in the northern hemisphere 12-07-14 VH2 CYCLE5 10 orbits of VIR VIS+IR pushbroom cubes in the equatorial region 12-07-20 VH2 CYCLE6 10 orbits of VIR VIS+IR pushbroom cubes in the northern hemisphere ------------------------------------------------------------------------ 12-07-25 VTC TRANSFER_ Vesta Transfer to Ceres Phase TO_CERES ------------------------------------------------------------------------ 12-08-25 VTC RC4 Ride-along cubes to FC rotational characterization movie #4 Processing : The data in this data set are calibrated, CODMAC Level 3 data. The data processing includes spectral, geometric, flat-field, and radiometric calibration. The details of how these calibrations were performed are described in the VIR_CALIBRATION document contained the DOCUMENT/CALIBRATION directory of this archive. This document describes how the calibration parameters were derived an gives a procedure for generating the calibrated data set from the raw EDR data set DAWN-A-VIR-2-EDR-IR-VESTA-SPECTRA-V2.0. Files containing the calibration parameters and referenced in the calibration procedure are located in the CALIB directory of this archive The VIR calibration has been updated departure from Vesta, where the data were initially processed using a version 1 (V1) set of files. The V1 responsivity does not provide calibration factors for spectral bands between 160 and 238 (roughly 2.5-3.3um). To solve this problem the internal calibration lamps were used and assumed to be a black body source. First the raw signal of the internal calibration lamp was calibrated with the V1 responsivity. Then the equivalent temperature was determined for the 3.5-5.0 um region. The next step was to compute the Planck function at the equivalent temperature. Responsivity V2 is the result of the ratio between the raw signal of the lamp and the computed Planck function. This ratio has been multiplied by a factor to take into account the integration time used to acquire the signal, the transmittance of the polystyrene filter on the calibration lamp, and the viewing geometry. Responsivity V2 minimizes most calibration residuals present in the previous version (V1). However, the Vesta mision phases VSH and VH2 are still affected by a major contamination in the spectral bands 190 to 238 (wavelength 2.8 to 3.3). It is VIR team practice to consider the entire collection of calibration files as a single unit so the version number of every file was incremented to V2 even though only the IR responsivity file was updated. Data : The data are in PDS format. A detailed description of the data format is given in the VIR SIS document located in the DOCUMENT directory of this data set. Ancillary Data : No ancillary data included in this data set. Coordinate System : The geometry items SC_SUN_POSITION_VECTOR, SC_TARGET_POSITION_VECTOR and SC_TARGET_VELOCITY_VECTOR provided in the label of the data product are relative to the Earth Mean Equator frame of J2000. SUB_SPACECRAFT_LATITUDE, SUB_SPACECRAFT_LONGITUDE are given in the PLANETOCENTRIC coordinate system. These parameters are corrected for planetary and stellar aberrations. Distances are given in km, angles in degrees.
|
| DATA_SET_RELEASE_DATE |
2016-05-06T00:00:00.000Z
|
| START_TIME |
2011-05-03T12:00:00.000Z
|
| STOP_TIME |
2012-08-26T02:38:00.000Z
|
| MISSION_NAME |
DAWN MISSION TO VESTA AND CERES
|
| MISSION_START_DATE |
2007-09-27T12:00:00.000Z
|
| MISSION_STOP_DATE |
2017-06-30T12:00:00.000Z
|
| TARGET_NAME |
4 VESTA
|
| TARGET_TYPE |
ASTEROID
|
| INSTRUMENT_HOST_ID |
DAWN
|
| INSTRUMENT_NAME |
VISIBLE AND INFRARED SPECTROMETER
|
| INSTRUMENT_ID |
VIR
|
| INSTRUMENT_TYPE |
IMAGING SPECTROMETER
|
| NODE_NAME |
Small Bodies
|
| ARCHIVE_STATUS |
LOCALLY ARCHIVED
|
| CONFIDENCE_LEVEL_NOTE |
Confidence Level Overview : Data confidence is nominal, meaning that all data have been validated by the VIR team and found as expected. Any exceptions are noted by the DATA_QUALITY field in the label files. Review : These are the same data files that were utilized by the Dawn Science Team. Any errors or deficiencies reported by the Science Team were corrected by the VIR team. Note, however, that the geometry information provided in the PDS labels was updated to reflect the IAU (Claudia Double Prime) coordinate system and peer review issues have been resolved. A full PDS peer review was conducted of all products in this data set. Data Coverage and Quality : Data quality is good unless otherwise noted by the DATA_QUALITY keyword. VIR spectra are affected by residual systematic errors due to imperfect radiometric and spectral calibration that influence the quality of imaging spectrometer data. The data are affected by systematic deviations from spectrum of the target due to imperfect radiometric standards, by spectral miscalibration, and by systematic errors resulting from uncertainties in the solar reference spectrum. The spectral images can show 'stripes' due to the slight deviation that exists between the input/output transfer function of each sample of the detector. These stripes are particularly evident when the signal is very low. Visible channels with a wavelength > 0.95 microns cannot be used for scientific analysis, because of the straylight effect which currently has no correction. By excluding these wavelengths from the spectrum, the offset between the visible and the infrared channels in the range where they meet disappear. In some sporadic cases where this offset can still be observed, the instrument team recommends scaling the IR channel to the VIS channel, having the latter a good agreement with the Framing Camera dataset. The instrument team is working to resolve some of the issues described here. The team plans to release, in the near future, a new level of derived data products that will partially solve the problems above reported. Dropouts that may be observed in some images are due to instrument saturation. The spectral range in which these dropouts occur varies depending upon exposure duration, target topography, and incidence angle. Contamination has been noted in the IR data due to the buildup of some unidentified substance on the instrument sensor. The contamination is in the 3-micron region and is related to cold-trapped volatiles which mimic a water vapor absorption. This contamination is mitigated by the frequent powering off of the cryocooler, allowing the sensor to warm and the substance to evaporate. Contamination was most prevalent during Vesta HAMO and to a lesser extent Vesta HAMO 2 as the cryocooler was turned on throughout all of HAMO (32 days), and up to 2 weeks during HAMO 2. Limitations : No limitations on these data
|
| CITATION_DESCRIPTION |
De Sanctis, M.C., M.T. Capria, E. Ammannito, M. Giardino, S. Fonte, R. Noschese, A. Coradini, DAWN VIR CAL (RDR) VESTA INFRARED SPECTRA V2.0, DAWN-A-VIR-3-RDR-IR-VESTA-SPECTRA-V2.0, NASA Planetary Data System, 2016.
|
| ABSTRACT_TEXT |
This data set contains the spectral radiance (W/(m**2*sr*micron)) data from the Dawn VIR instrument infrared channel for all Vesta encounter mission phases. The data in this version of the data set have been produced using an updated calibration. The data cover the time period between 2011-05-03 and 2012-07-18.
|
| PRODUCER_FULL_NAME |
MARIA CRISTINA DE SANCTIS
|
| SEARCH/ACCESS DATA |
SBN PSI WEBSITE
|
|
.png)
.png)
