PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM LABEL_REVISION_NOTE = "2013-07-31 Peplowski" OBJECT = DATA_SET DATA_SET_ID = "DAWN-A-GRAND-5-VESTA-HEGR-COUNTS-V1.0" OBJECT = DATA_SET_INFORMATION DATA_SET_NAME = "DAWN GRAND MAP VESTA HEGR COUNTS V1.0" DATA_SET_COLLECTION_MEMBER_FLG= "N" ARCHIVE_STATUS = "LOCALLY ARCHIVED" DATA_OBJECT_TYPE = "TABLE" START_TIME = 2011-12-12T00:00 STOP_TIME = 2012-05-01T00:00 DATA_SET_RELEASE_DATE = 2013-08-01 PRODUCER_FULL_NAME = "PATRICK N. PEPLOWSKI" DETAILED_CATALOG_FLAG = "N" DATA_SET_TERSE_DESC = "Global map of the high-energy gamma-ray count rates within the regolith of asteroid 4 Vesta acquired by the NASA Dawn mission's Gamma Ray and Neutron Detector from low altitude [PEPLOWSKIETAL2013]." ABSTRACT_DESC = "This data product describes a map of the high-energy gamma-ray (HEGR) count rate across the surface of Vesta. As shown in PEPLOWSKIETAL2013, HEGRS are sensitive to the bulk elemental composition of the near surface material, particularly its heavy major-element content." CITATION_DESC = "Peplowski et al., Dawn GRaND high-energy gamma-ray counting rate map, DAWN-A-GRAND-5-VESTA-HEGR-COUNTS-V1.0, NASA Planetary Data System, 2013." DATA_SET_DESC = " Data Set Overview ================= This data product describes a map of the high-energy gamma-ray (HEGR) count rate across the surface of Vesta. As shown in PEPLOWSKIETAL2013, HEGRS are sensitive to the bulk elemental composition of the near surface material, particularly its heavy major-element content. Parameters ========== Each row of the table provides the high-energy gamma-ray (HEGR) count rate information 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 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 HEGR_COUNTING_RATE (E14.4) HEGR count rate c/s 8 HEGR_COUNTING_RATE_UNCERTAINTY (E14.4) HEGR count rate uncertainties c/s 9 HEGR_SAMPLES (I10) Number of samples per pixel c/s" CONFIDENCE_LEVEL_NOTE = " Confidence Level Overview ========================= The data set is a high order data product derived from gamma-ray counting data acquired by GRaND in LAMO as described by PEPLOWSKIETAL2013. 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 high-energy gamma ray count rate contributions from Vesta's regolith. There are no gaps in coverage. The depth sampled by high-energy gamma rays is a few 10s of 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 the leakage flux of high-energy gamma rays produced within Vesta's regolith are described by PEPLOWSKIETAL2013. We note that the tabulated values give the high-energy gamma ray count rates after correcting for background signals and variability due to solid angle, orientation, and galactic cosmic rays. The data are subsequently smoothed over the footprint of the GRaND instrument. The resuling values are proportional to the heavy major-element composition of the surface." 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