PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT INTERCHANGE_FORMAT = ASCII PUBLICATION_DATE = 2017-10-19 NOTE = "Readme" END_OBJECT = TEXT END Ceres Radio Science Derived Ceres Gravity Data Archive VERSION 2.0 (DAWN-A-RSS-5-CEGR-V2.0) AAREADME.TXT 2017-09-22 Dustin Buccino Jet Propulsion Laboratory ============================================================================== INTRODUCTION ============================================================================== This archive contains derived gravity data for the Dawn Radio Science Gravity Field Determination experiments during the Ceres encounter, including spherical harmonics. The data are derived from the Dawn raw radio science data set (DAWN-A-RSS-1-CEGR-V1.0), observations made using the Dawn spacecraft and Earth-based receiving stations of the NASA Deep Space Network (DSN). Modification History ==================== Note this is version 2 of the gravity field, which has the corrected location of the Kait crater. During the development of higher-level data products for Dawn, the Gravity team discovered that the Gravity team and the imaging team were using different craters to define the coordinate system. Under concurrence from the Dawn project, the gravity team corrected the gravity field products to align with data products used by other teams. The corrected location of the Kait crater is a rotation of -0.064074 deg about the z-axis. The corresponding version 2 of the gravity field re-estimates the gravity field parameters, pole right ascension, declination, prime meridian, and rotation rate. The version 2 gravity field fixes the y-axis coordinate to align exactly with the Kait landmark crater. Details of the coordinate system are described in the corresponding labels for the DATA/SHADR and DATA/SHBDR data products. Because the gravity field was re-estimated in this new frame, the gravitational field parameters and pole frame are slightly different from the previous version. The change is large enough to affect the DATA/SHADR and DATA/SHBDR data products, which have been updated in the version 2 dataset but not large enough to affect the 1-degree resolution of the DATA/RSDMAP products, which remain unchanged. ============================================================================== ARCHIVE INFORMATION ============================================================================== This archive has the structure illustrated in the diagram below. The data product types archived in this data set are the Spherical Harmonics ASCII Data Record (SHADR), Spherical Harmonics Binary Data Record (SHBDR), and the Radio Science Digital Map (RSDMAP). The CATALOG directory contains summary information on the Dawn mission, the spacecraft, radio science instrumentation, the data set, and listings of references and personnel. These files are structured to facilitate machine handling but are also intended to be human readable. The diagram below shows the organization of this volume, starting from the root directory. |===================================================================| | | | Dawn Gravity/Radio Science | | Derived Data Directory Structure for Ceres | | | |===================================================================| | | | root | | | | | |- AAREADME.TXT | | |- VOLDESC.CAT | | | | | |- [CATALOG] | | | |- CATINFO.TXT | | | |- DAWNMISSION.CAT | | | |- DAWNINSTHOST.CAT | | | |- INST.CAT | | | |- REF.CAT | | | |- PERSON.CAT | | | `- DATASET.CAT | | | | | |- [DOCUMENT] | | | |- DOCINFO.TXT | | | |- ... | | | | | |- [INDEX] | | | |- INDXINFO.TXT | | | |- INDEX.LBL | | | `- INDEX.TAB | | | | | `- [DATA] | | |- [SHADR] | | |- [SHBDR] | | `- [RSDMAP] | | | |===================================================================| ============================================================================== FILE FORMAT ============================================================================== All data files in the archive are accompanied by detached PDS labels, which describe their contents. Image data files have the extension ".IMG"; binary tables have the extension ".DAT", and ASCII tables have the extension ".TAB". A detached PDS label has the same file name as the data file it describes except that the label name has the suffix ".LBL". Detailed documentation on file structure, contents, and formatting is found in the PDS labels and in the Software Interface Specifications (SISs) in the DOCUMENT directory. Text files (*.TXT file names) and catalog files (*.CAT file names) are stream files. ============================================================================== CITATIONS ============================================================================== Users wishing to cite products in this archive may use the following citation: Park, R.S., et. al., Dawn Ceres Derived Gravity Data, NASA Planetary Data System, DAWN-A-RSS-5-CEGR-V1.0, 2017. ============================================================================== COGNIZANT PERSONNEL ============================================================================== Alex Konopliv Gravity Science Co-Investigator Jet Propulsion Laboratory 4800 Oak Grove Drive M/S: 301-121 Pasadena, CA 91109-8099 Tel: 818-354-6105 FAX: 818-394-5904 Alexander.S.Konopliv@jpl.nasa.gov Ryan Park Chair of the Gravity Science Working Group Jet Propulsion Laboratory 4800 Oak Grove Drive M/S: 301-121 Pasadena, CA 91109-8099 Tel: 818-354-4401 FAX: 818-394-5904 Ryan.S.Park@jpl.nasa.gov Dustin Buccino Radio Science Analyst Jet Propulsion Laboratory 4800 Oak Grove Drive M/S: 230-215 Pasadena, CA 91109-8099 Tel: 818-393-1072 FAX: 818-393-9282 Dustin.R.Buccino@jpl.nasa.gov ============================================================================== ACRONYMS AND ABBREVIATIONS ============================================================================== ASCII American Standard Code for Information Interchange DOY Day of year DSN Deep Space Network JPL Jet Propulsion Laboratory NAIF Navigation Ancillary Information Facility NASA National Aeronautics and Space Administration PDS Planetary Data System RS Radio Science RSDMAP Radio Science Digital Map RSS Radio Science Subsystem SHA Spherical Harmonics ASCII Data Record SIS Software Interface Specification