PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM ^TEXT = "AAREADME.TXT" OBJECT = TEXT PUBLICATION_DATE = 2013-08-01 NOTE = "AAREADME.TXT describes this volume." END_OBJECT = TEXT END Volume DWNVGRD_2 Dawn GRaND High Level (2/3) Vesta Encounter Archive ============================================================================== Brief Disk Description ============================================================================== This volume contains data from the Dawn GRaND high level (DDR/MAPS) Vesta Encounter data sets. The data sets a listed below, along with publicly available papers which describe them. Each data set includes a brief dataset catalog file, which describes the map data, coordinate systems, methods to convert tabulated data to physical units (if available), and any other prerequisites for use of the data. The Dawn Geochemistry team has adopted a common format for PDS high level map products, which are presented as ASCII tables. An International Data Language (IDL) function is included in EXTRAS directory to read and display map data. The format allows for different tesselation schemes (e.g. cylindrical or quasi-equal-area pixels), which are described in the label and catalog files for each data set. The pixel geometry selected depends on the intended use of the maps and quality of the data, among other factors. For example, the hydrogen abundance map is a smoothed data set, presented as a 0.5 deg cylindrical map, which is useful for visual comparisons with other map products (overlays & contours). Details of the data reduction and analysis methodology, including binning and smoothing, can be found in the publications accompanying each of the data sets. A list of avialable data sets and references follows: Dawn GRaND Vesta Neutron Absorption Map - Global map of the thermal neutron absorption cross section of Vesta's regolith. The data are presented as a unitless compositional parameter along with 1-sigma uncertainties. Expressions to convert the data to absorption units are provided in the catalog file. The thermal neutron absorption cross section depends primarily on the concentration of Fe, Ca, Al, Ti. The absorption data is sensitive to petrology (e.g. the percentage of eucritic material in howardite). Prettyman, T., et al. (2013), Neutron absorption constraints on the composition of 4 Vesta, Meteoritics & Planetary Science, Vol. 48, Issue 11, pp. 2211-2236, doi: 10.1111/maps.12244. [PRETTYMANETAL2013] Dawn GRaND Vesta Fast Neutron Residual Map - This global map of fast neutron residual counting rates is sensitive to variations in the concentration of elements other than hydrogen. An analysis of the sensitivity of the fast residuals to atomic mass is presented in the following manuscript. Lawrence, D.J., et al. (2013), Constraints on Vesta's Elemental Composition: Fast Neutron Measurements by Dawn's Gamma Ray and Neutron Detector, Meteoritics & Planetary Science, Vol. 48, Issue 11, pp. 2271-2288, doi:10.1111/maps.12187. [LAWRENCEETAL2013] DawN GRaND Vesta High Energy Gamma-Ray Counts Map - A global map of the high energy gamma ray (HEGR) continuum measured by GRaND's bismuth germanate scintillator is sensitive to the atomic mass and atomic number of Vesta's regolith. Peplowski, P.N., et al. (2013), Compositional variability on the surface of 4 Vesta revealed though GRAND measurements of high-energy gamma rays, Meteoritics & Planetary Science, Vol. 48, Issue 11, pp. 2252-2270, doi:10.1111/maps.12176. [PEPLOWSKIETAL2013] Dawn GRaND Vesta Hydrogen Abundance Map - This is a global map of the distribution of hydrogen (micrograms/gram) on Vesta. A smoothed, 0.5 deg cylindrical map is provided. Prettyman, T.H., et al. (2012), Elemental Mapping by Dawn Reveals Exogenic H in Vesta's Regolith, Science 338(6104):242-246, DOI 10.1126/science.1225354. [PRETTYMANETAL2012] Dawn GRaND Vesta Fe Gamma-Ray Uncorrected Counts Map - This is a global map of the intensity (counts/s) of the 7.6 MeV gamma ray produced by neutron capture with Fe. An additional correction for variations in neutron number density is needed in order to derive a quantity that is proportional to the concentration of Fe (see below). Yamashita, N., et al. (2013), Distribution of iron on Vesta, Meteoritics & Planetary Science, Vol. 48, Issue 11, pp. 2237-2251, doi:10.1111/maps.12139. [YAMASHITAETAL2013] Dawn GRaND Vesta Fe Gamma-Ray Corrected Counts Map - This is a global map of the intensity (counts/s) of the 7.6 MeV gamma ray produced by neutron capture with Fe. All corrections have been applied such that the intensity is proprotional to Fe concentration. An expression to convert counting rate to Fe concentration (wt.%) is provided in the catalog file. Yamashita, N., et al. (2013), Distribution of iron on Vesta, Meteoritics & Planetary Science, Vol. 48, Issue 11, pp. 2237-2251, [YAMASHITAETAL2013] These map data sets have been generated from the GRaND L-1B data taken during the Vesta Science Low Altitude Mapping Orbit phase (VSL) of the Dawn mission. The Dawn GRaND Vesta L-1B will be archived in PDS as the DAWN-A-GRAND-3-RDR-CRUISE-COUNTS-V1.0 data set. NOTE: Reading the Science Plan (DOCUMENTS/SCIENCE_PLAN/DAWN_SCIPLAN_V4_4.PDF) is critical to the understanding of the Vesta observations and science objectives. Other critical documentation in the DOCUMENT directory include the volume SIS and calibration procedure. All data are stored in the 'DATA' branch of the directory tree. In addition to the data files, anciliary information is stored in a separate PDS label (.LBL) file. Users of these data are encouraged to acknowledge both the PDS and the principal investigators of the instruments whose data is used in analysis in all publications. ============================================================================== Volume Set Information ============================================================================== This volume is part of the GRaND high level data volume set. This volume set includes the following volumes: Volume ID Description ------------------------------------------------------------ DWNVGRD_2 Dawn GRaND L2/3 DDR/MAP Vesta Encounter images DWNCGRD_2 Dawn GRaND L2/3 DDR/MAP Ceres Encounter images ============================================================================== Mission Facts ============================================================================== The 'Dawn Vesta Science Phases' table below provides a list Dawn Vesta Encounter mission phase start dates. ------------------------------------------------------------------------------ Dawn Vesta Science Phases ------------------------------------------------------------------------------ start date (DOY) Phase Name (ID) ------------------------------------------------------------------------------ 2011-05-03 (123) VESTA SCIENCE APPROACH (VSA) 2011-08-11 (223) VESTA SCIENCE SURVEY (VSS) 2011-08-31 (243) VESTA TRANSFER TO HAMO (VTH) 2011-09-29 (272) VESTA SCIENCE HAMO (VSH) 2011-11-02 (306) VESTA TRANSFER TO LAMO (VTL) 2011-12-12 (346) VESTA SCIENCE LAMO (VSL) 2012-05-01 (122) VESTA TRANSFER TO HAMO 2 (VT2) 2012-06-15 (167) VESTA SCIENCE HAMO 2 (VH2) 2012-07-25 (207) VESTA TRANSFER TO CERES (VTC) ------------------------------------------------------------------------------ ============================================================================== File Formats ============================================================================== The data files on this volume are in both ASCII. Each data file has an detached ASCII header (PDS label). The PDS label contains information describing spacecraft, target, and data record format. A data set description, instrument description, and other PDS documents are in .CAT files in the /CATALOG directory. Additional documentation is generally located in the DOCUMENT directory. Note for Windows users: In more recent versions of the Microsoft Windows operating system the .CAT by default is reserved as 'Security Catalog.' The .CAT files contained in this volume are ASCII text files, and can be read by any form of text editor. To make Windows open files with this name extension as text files, do the following. To make Windows open files with this name extension as text files right click the .CAT file, select with and choose a text editor to open the file. ============================================================================== Errata ============================================================================== Every effort has been made to insure that the data and documentation are of the best possible quality. However, mistakes are inevitable. There is a file called ERRATA.TXT found at the root level of this volume which contains a list of known deficiencies or caveats associated with data on this volume at the time this volume was produced. ============================================================================== Volume Contents and Structure ============================================================================== This section describes the volume structure and naming conventions. Below is a tree diagram of the volume, followed by a description of the directory function and key files in each directory. DWNVGRD_2 (root directory) | |- AAREADME.TXT Describes volume contents, and organization (this file) | |- ERRATA.TXT Describes known deficiencies or caveats in the data or | on this volume. | |- VOLDESC.CAT High level description of volume contents. | |- [BROWSE] Contains a PDF plot of the data located in the DATA brach | of this volume. More information on the contents of this | directory is provided in the file /BROWSE/BROWINFO.TXT. | |- [CATALOG] PDS catalog files containing information describing the | data, instrument, instrument personnel, relevant references, | the spacecraft, and mission. More information on the contents | of this directory is provided in the file | /CATALOG/CATINFO.TXT. | |- [DATA] Contains the data files. The data are divided up into | separate subdirectories by data set. | |- [DOCUMENT] Contains documents describing the instrument, and data | acquisition, processing, and usage. More information on the | contents of this directory is provided in the file | /DOCUMENT/DOCINFO.TXT. | |- [EXTRAS] Contains files which facilitate the use of the data on the | disk, but which are not actually required for the use or | understanding of those data. A more detailed description of | the contents of this directory is provided in the file | /EXTRAS/EXTRINFO.TXT. | |- [INDEX] Contains a table of contents for all files located on this | volume, and the volume set to date. A more detailed | description of the contents of this directory is provided in | the file /INDEX/INDXINFO.TXT. ============================================================================ Contacts ============================================================================ This volume was produced for the Planetary Data System (PDS) at the Small Bodies node. The data, and associated metadata were supplied by Dr. Thomas H. Prettyman, of the Planetary Science Institute. The volume was assembled at the Dawn Science Center (DSC), by Joseph N. Mafi. For questions or problems regarding the volume, please contact Dr. Mark Sykes at the PDS Small Bodies Node: Email neese@psi.edu Telephone 520-622-6300 Mail Carol Neese Planetary Science Institute 1700 E. Ft. Lowell, Ste. 106 Tuscon, AZ 85719-2395 USA For question regarding the data, please contact Dr. Tom Prettyman of PSI: Email prettyman@psi.edu Telephone 505-690-5128 Mail Planetary Science Institute Albuquerque, NM USA For questions regarding PDS Standards or other archives available from the PDS, please contact PDS Operator at the PDS Engineering Node (at JPL): Email pds_operator@jpl.nasa.gov Telephone 818-354-4321 Mail Planetary Data System, PDS Operator Jet Propulsion Laboratory Mail Stop 202-101 4800 Oak Grove Dr. Pasadena, CA 91109-8099 USA The PDS assumes no legal liability for errors on this disk. All users are encouraged to verify the correctness of the data prior to submitting any publications or other work based on these data. Please report errors on this disk to the Small Bodies Node of the PDS through the ERRATA reporting procedures described above.