PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM LABEL_REVISION_NOTE = "2013-07-31 Prettyman Original" OBJECT = DATA_SET DATA_SET_ID = "DAWN-A-GRAND-5-VESTA-FAST-RESIDUAL-V1.0" OBJECT = DATA_SET_INFORMATION DATA_SET_NAME = "DAWN GRAND MAP VESTA FAST NEUTRON RESIDUAL V1.0" DATA_SET_COLLECTION_MEMBER_FLG= "N" ARCHIVE_STATUS = "LOCALLY ARCHIVED" DATA_OBJECT_TYPE = "TABLE" START_TIME = 2011-12-09T00:00:00 STOP_TIME = 2012-05-01T01:59:29 DATA_SET_RELEASE_DATE = 2013-08-01 PRODUCER_FULL_NAME = "DAVID J. LAWRENCE" DETAILED_CATALOG_FLAG = "N" DATA_SET_TERSE_DESC = "Global map of fast neutron residual count rates within the regolith of asteroid 4 Vesta acquired by the NASA Dawn mission's Gamma Ray and Neutron Detector from low altitude [LAWRENCEETAL2013B]." ABSTRACT_DESC = "These data are maps of fast neutron residual count rates from the GRaND plus Z boron loaded sensor. The nominal fast neutron count rates were detrended using the GRaND epithermal neutron map to produced this residual map. The residual map is related to the average atomic mass on Vesta. Details of the map and data reduction are described in LAWRENCEETAL2013B." CITATION_DESC = "Lawrence et al., Dawn GRaND fast neutron residual counting rate map, DAWN-A-GRAND-5-VESTA-FAST-RESIDUAL-V1.0, NASA Planetary Data System, 2013." DATA_SET_DESC = " Data Set Overview ================= These data are maps of fast neutron residual count rates from the GRaND plus Z BLP sensor. The nominal fast neutron count rates were detrended using the GRaND epithermal neutron map to produced this residual map. The residual map is related to the average atomic mass on Vesta. Details of the map, data reduction, and interpretation are described in LAWRENCETAL2013. Two time-contiguous datasets were used for the fast neutron analysis: period 1 - 2011-12-09T00:00:00 to 2012-01-14T06:48:00 period 2 - 2012-04-03T00:00:00 to 2012-05-01T01:51:29 Parameters ========== Each row of the table provides the abundance of hydrogen for a single rectangular pixel. The format for each row is '(i10,6(f7.1),f8.2)'. East longitude convention is used (-180 to 180 degrees). The longitudes are given in the Claudia Double Prime coordinate system (see Confidence Level Note). Each pixel spans a separate and unique portion of Vesta's surface, and together, the pixels provide full global coverage. The BROWSE directory displays the data as a global map. The column descriptions follow: COLUMN NAME FORMAT DESCRIPTION UNITS 0 PIXEL_INDEX (I10) N/A 1 MIN_LAT (F7.1) Pixel latitude lower boundary deg 2 MAX_LAT (F7.1) Pixel latitude upper boundary deg 3 DELTA_LAT (F7.1) Width of the pixel in latitude deg 4 MIN_LON (F7.1) Pixel longitude lower boundary deg 5 MAX_LON (F7.1) Pixel longitude upper boundary deg 6 DELTA_LON (F7.1) Width of the pixel in longitude deg 7 FAST_RESID (F7.3) Fast neutron residual counts/s" CONFIDENCE_LEVEL_NOTE = " Confidence Level Overview ========================= The data set is a high order data product derived from epithermal neutron counting data acquired by GRaND in LAMO as described by LAWRENCEETAL2013B. Review ====== This data set is in review by NASA Planetary Data System. Data Coverage and Quality ========================= The data set contains a global map of the fast neutron residual count rate within Vesta's regolith. There are no gaps in coverage. The depth sampled by fast neutrons is a few decimeters. Coordinate System: The data were analyzed and mapped in the Claudia coordinate system, in which the prime meridian passes close to a small crater named Claudia. In this coordinate system, the prominent Marcia crater is located at 190E longitude. Maps published by the Dawn Geochemistry Working Group in the literature are presented in the Claudia coordinate system [PRETTYANETAL2012, LAWRENCEETAL2013B, PEPLOWSKIETAL2013, PRETTYMANETAL2013, YAMASHITAETAL2013]. Consistent with IAU guidelines, maps of GRaND data in this archive are presented in the 'Claudia Double Prime' (CDP) coordinate system. CDP has the same pole position as Claudia such that latitudes are the same; however, the prime meridian of CDP is shifted by 210 degrees from that of Claudia, passing 20 degrees to the east of Marcia. The coordinate systems are describes in detail by J.-Y. Li in VESTA_COORDINATES_120918.pdf, which accompanies this archive in the DOCUMENTS directory. All of the maps use rectangular pixels with east longitudes within -180 to 180 degrees in the Claudia system. For archiving, the longitudes were converted to CDP as follows: longitude_CDP = longitude_Claudia - 210 degrees. If longitude_CDP is less than -180 degrees, add 360 degrees. For example, if longitude_Claudia = -170 (the location of Marcia crater), then longitude_CDP = -20. Similarly, longitudes in the CDP system can be converted to Claudia as follows: longitude_Claudia = longitude_CDP + 210. If longitude_Claudia is greater than 180 degrees, subtract 360 degrees. Thus, the pixel longitude boundaries, which were tabulated in this archive in the CDP system, can easily be converted back to the Claudia system, in which the data were analyzed, by the user when desired. To further facilitate comparison between the PDS archived maps and those published in the literature, a 'side-by-side' display of each map in the Claudia and CDP systems is included in the accompanying browse file (see BROWSE directory). For further clarification, we note that map pixels in the Claudia system always have MIN_LON < MAX_LON; however, when transformed into the CDP system, not all pixels will meet this condition. For example, in some quasi-equal area maps, the polar pixels have MIN_LON = -180 and MAX_LON = 180 in the Claudia coordinate system. These pixels span 360 degrees in longitude. When transformed to the CDP coordinate system, these pixels have MIN_LON = -30 and MAX_LON = -30, such that MIN_LON = MAX_LON. In addition, for some maps, a portion of the pixels will have MIN_LON > MAX_LON when transformed into the CDP system. To avoid confusion, we included the width of each pixel in longitude as DELTA_LON. For example, for the aforementioned polar pixels, DELTA_LON = 360. Limitations =========== Assumptions and limitations underlying the analysis of fast neutrons within Vesta's regolith are described by LAWRENCEETAL2013B. We note that the tabulated values give the fast neutron count rates after correcting for variations due to epithermal neutrons in the GRaND +Z sensor. The resulting residual fast neutron count rates are then related to the variation in average atomic mass across the surface of Vesta. Because the fast neutron counting data were smoothed with the approximate GRaND footprint, (LAWRENCEETAL2013B), the mapped data have high precision. Thus, statistical uncertainties are not reported." END_OBJECT = DATA_SET_INFORMATION OBJECT = DATA_SET_TARGET TARGET_NAME = "4 VESTA" END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_MISSION MISSION_NAME = "DAWN MISSION TO VESTA AND CERES" END_OBJECT = DATA_SET_MISSION OBJECT = DATA_SET_HOST INSTRUMENT_HOST_ID = "DAWN" INSTRUMENT_ID = "GRAND" END_OBJECT = DATA_SET_HOST OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "LAWRENCEETAL2013B" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "PEPLOWSKIETAL2013" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "PRETTYMANETAL2011" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "PRETTYMANETAL2012" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "PRETTYMANETAL2013" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "YAMASHITAETAL2013" END_OBJECT = DATA_SET_REFERENCE_INFORMATION END_OBJECT = DATA_SET END