PDS_VERSION_ID = PDS3 RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 122 FILE_RECORDS = 2927 ^SHADR_HEADER_TABLE = ("JGM75E01.SHA",1) ^SHADR_COEFFICIENTS_TABLE = ("JGM75E01.SHA",3) INSTRUMENT_HOST_NAME = "MARS GLOBAL SURVEYOR" TARGET_NAME = "MARS" INSTRUMENT_NAME = "RADIO SCIENCE SUBSYSTEM" DATA_SET_ID = "MGS-M-RSS-5-SDP-V1.0" OBSERVATION_TYPE = "GRAVITY FIELD" ORIGINAL_PRODUCT_ID = "MGS75E" PRODUCT_ID = "JGM75E01.SHA" PRODUCT_RELEASE_DATE = 2001-01-01 DESCRIPTION = " This file contains coefficients and related data for the MGS75E Spherical Harmonic model of the Mars gravity field. MGS75E is a 75x75 spherical harmonics model with power rule constraints applied to harmonics above degree 59. It was derived from radio tracking of: Mariner 9 1971-11-14 to 1972-04-14 Viking Orbiter 1 1976-06-21 to 1978-11-18 Viking Orbiter 2 1977-03-02 to 1978-07-25 MGS Science Phasing Orbit 1 (SPO1) 1998-03-28 to 1998-04-28 Science Phasing Orbit 2 (SPO2) 1998-06-04 to 1998-09-23 Gravity Calibration Orbit (GCO) and 1999-02-02 to 1999-03-29 Fixed High-Gain Antenna Mapping (FHGA) Mapping (MAP) 1999-03-29 to 2000-09-29 Some details describing this model are: The spherical harmonic coefficients are fully normalized. The associated GM = 42828.377043 km**3/sec**2 The reference radius = 3394.20 km The Mars-fixed reference frame is given by the IAU 1991 constants The radio tracking data blocks consist of: Mariner 9 with 47,598 observations; Viking Orbiter 1 with 65,727 observations; Viking Orbiter 2 with 65,520 observations; SPO1 and SPO2 at 177 km periapsis with 133,600 observations; GCO at 370 km periapsis with 154,702 observations. MAP at 370 km periapsis with 1,352,266 observations (to 2000-09-29). The data weights for each block have accounted for the SPO1 and SPO2 Doppler being corrupted by solar plasma while at small Sun-Earth-probe angles. The GCO and MAP data are the highest quality data having a 2-way Doppler data weight of 0.1 mm/sec for a 10 second sample. The main contribution of the MGS GCO and MAP data is its global data coverage with a mean altitude about 400 km. Correlation of MGS75E model with topography model from the MOLA is generally strong for large/medium scale features, and has been improved significantly above degree 50 compared to MGS75B solution. This file is a pair of ASCII tables: a header table and a table of 5772 coefficients (plus a value for GM). Definitions of the tables follow. The MGS75E gravity model is delivered in the Spherical Harmonics Gravity ASCII Data Record (SHGADR) and is produced by the Mars Global Surveyor Gravity Science Team at JPL under the direction of William L. Sjogren. NB: START_ORBIT_NUMBER in keywords below is counted from Mars Orbit Insertion in September 1997. The MGS Project reset its orbit count at the beginning of Mapping in early March 1999; STOP_ORBIT_NUMBER is counted from the reset in 1999." START_ORBIT_NUMBER = 202 STOP_ORBIT_NUMBER = 6983 START_TIME = 1998-03-28T00:00:00 STOP_TIME = 2000-09-29T14:00:00 PRODUCT_CREATION_TIME = 2001-01-01T00:00:00.000 PRODUCER_FULL_NAME = "WILLIAM L. SJOGREN" PRODUCER_INSTITUTION_NAME = "JET PROPULSION LABORATORY" PRODUCT_VERSION_TYPE = "PRELIMINARY" PRODUCER_ID = "MGS GRAVSCI TEAM" SOFTWARE_NAME = "SHAGRV.V1.0" OBJECT = SHADR_HEADER_TABLE ROWS = 1 COLUMNS = 8 ROW_BYTES = 137 ROW_SUFFIX_BYTES = 107 INTERCHANGE_FORMAT = ASCII DESCRIPTION = "The SHADR header includes descriptive information about the spherical harmonic coefficients which follow in SHADR_COEFFICIENTS_TABLE. The header consists of a single record of eight (delimited) data columns requiring 137 bytes, a pad of 105 unspecified ASCII characters, an ASCII carriage-return, and an ASCII line-feed." OBJECT = COLUMN NAME = "REFERENCE RADIUS" DATA_TYPE = ASCII_REAL START_BYTE = 1 BYTES = 23 FORMAT = "E23.16" UNIT = "KILOMETER" DESCRIPTION = "The assumed reference radius of the spherical planet." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "CONSTANT" DATA_TYPE = ASCII_REAL START_BYTE = 25 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "For a gravity field model the assumed gravitational constant GM in kilometers cubed per seconds squared for the planet. For a topography model, set to 1." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "UNCERTAINTY IN CONSTANT" DATA_TYPE = ASCII_REAL START_BYTE = 49 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "For a gravity field model the uncertainty in the gravitational constant GM in kilometers cubed per seconds squared for the planet. For a topography model, set to 0." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "DEGREE OF FIELD" DATA_TYPE = ASCII_INTEGER START_BYTE = 73 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The degree of model field." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "ORDER OF FIELD" DATA_TYPE = ASCII_INTEGER START_BYTE = 79 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The order of the model field." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "NORMALIZATION STATE" DATA_TYPE = ASCII_INTEGER START_BYTE = 85 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The normalization indicator. For gravity field: 0 coefficients are unnormalized 1 coefficients are normalized 2 other." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "REFERENCE LONGITUDE" POSITIVE_LONGITUDE_DIRECTION = "EAST" DATA_TYPE = ASCII_REAL START_BYTE = 91 BYTES = 23 FORMAT = "E23.16" UNIT = "DEGREE" DESCRIPTION = "The reference longitude for the spherical harmonic expansion; normally 0." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "REFERENCE LATITUDE" DATA_TYPE = ASCII_REAL START_BYTE = 115 BYTES = 23 FORMAT = "E23.16" UNIT = "DEGREE" DESCRIPTION = "The reference latitude for the spherical harmonic expansion; normally 0." END_OBJECT = COLUMN END_OBJECT = SHADR_HEADER_TABLE OBJECT = SHADR_COEFFICIENTS_TABLE ROWS = 2925 COLUMNS = 6 ROW_BYTES = 107 ROW_SUFFIX_BYTES = 15 INTERCHANGE_FORMAT = ASCII DESCRIPTION = "The SHADR coefficients table contains the coefficients for the spherical harmonic model. Each row in the table contains the degree index m, the order index n, the coefficients Cmn and Smn, and the uncertainties in Cmn and Smn. The (delimited) data require 107 ASCII characters; these are followed by a pad of 13 unspecified ASCII characters, an ASCII carriage- return, and an ASCII line-feed." OBJECT = COLUMN NAME = "COEFFICIENT DEGREE" DATA_TYPE = ASCII_INTEGER START_BYTE = 1 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The degree index m of the C and S coefficients in this record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "COEFFICIENT ORDER" DATA_TYPE = ASCII_INTEGER START_BYTE = 7 BYTES = 5 FORMAT = "I5" UNIT = "N/A" DESCRIPTION = "The order index n of the C and S coefficients in this record." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "C" DATA_TYPE = ASCII_REAL START_BYTE = 13 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "The coefficient Cmn for this spherical harmonic model." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "S" DATA_TYPE = ASCII_REAL START_BYTE = 37 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "The coefficient Smn for this spherical harmonic model." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "C UNCERTAINTY" DATA_TYPE = ASCII_REAL START_BYTE = 61 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "The uncertainty in the coefficient Cmn for this spherical harmonic model." END_OBJECT = COLUMN OBJECT = COLUMN NAME = "S UNCERTAINTY" DATA_TYPE = ASCII_REAL START_BYTE = 85 BYTES = 23 FORMAT = "E23.16" UNIT = "N/A" DESCRIPTION = "The uncertainty in the coefficient Smn for this spherical harmonic model." END_OBJECT = COLUMN END_OBJECT = SHADR_COEFFICIENTS_TABLE END