PDS_VERSION_ID = "PDS3" RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 122 FILE_RECORDS = 2557 ^SHADR_HEADER_TABLE = ("JGDWN_C70E01_ISOSIG_SHA.TAB",1) ^SHADR_COEFFICIENTS_TABLE = ("JGDWN_C70E01_ISOSIG_SHA.TAB",3) INSTRUMENT_HOST_NAME = "DAWN" TARGET_NAME = "CERES" INSTRUMENT_NAME = "RADIO SCIENCE SUBSYSTEM" DATA_SET_ID = "DAWN-A-RSS-5-CEGR-V4.0" OBSERVATION_TYPE = "GRAVITY FIELD" ORIGINAL_PRODUCT_ID = "CERES70E_ISOSIG" PRODUCT_ID = "JGDWN_C70E01_ISOSIG_SHA.TAB" PRODUCT_RELEASE_DATE = 2019-04-04 DESCRIPTION = " This file contains coefficients and related data for the CERES70E_ISOSIG spherical harmonic gravity model of Ceres. CERES70E_ISOSIG is a 70th degree and order model obtained from radiometric tracking (Doppler and range data) and optical landmarks of the Dawn spacecraft in orbit about Ceres. The gravity model includes Prime Mission data from the Approach phase to the end of the LAMO orbit. The data span is Feb 2, 2015 to Sept 2, 2016. Optical landmark tracking is included for LAMO and HAMO phases. The Doppler and landmark tracking is also included for the Extended Mission-2 phase from June 6, 2018 to October 31, 2018. This gravity field is consistent with the final SPC shape model of Ceres (Park et al. High resolution shape model of Ceres from stereophotoclinometry using Dawn imaging data, Icarus, 2019). More details can be found in Park, R.S., Konopliv, A.S., Ermakov, A.I. et al. Evidence of non-uniform crust of Ceres from Dawn's high-resolution gravity data. Nat Astron 4, 748-755 (2020). https://doi.org/10.1038/s41550-020-1019-1 Some details describing this model are: The spherical harmonic coefficients are fully normalized. The associated GM = 62.6288985790 km^3/s^2 The reference radius = 470.0 km The Ceres-fixed reference frame prime meridian and pole location in IAU coordinates are fixed to CERES18D values: Right ascension = 291.42763 degrees RA rate = 0.0 degrees/cty Declination = 66.76033 degrees Dec rate = 0.0 degrees/cty Prime Meridian = 170.309 degrees Rotation rate = 952.1532635 degrees/day The pole location, W0 and spin rate were determined in the CERES18D gravity field by fixing the y-value of the Kait landmark to zero. The uncertainties of the pole for CERES18D solution are Right ascension = 0.0002 degrees Declination = 0.0002 degrees The gravity field is constrained using a coefficient sigma constraint equal to the value of the expected isostatic gravity field. Observations for the gravity field consist of Doppler and range measurements from Deep Space Network (DSN) tracking. The count time for the Doppler observations is 60 seconds. The typical accuracy for the Doppler is 0.02-0.03 mm/s for the 60 second sample time. The range accuracy is about 1-2 meters and is limited by the station calibration accuracy. The actual rms scatter is less than 0.3 meters in spacecraft position. This product is a set of two ASCII tables: a header table and a coefficients table with 5037 coefficients and a GM value. Definitions of the tables follow. The CERES70E_ISOSIG gravity model is delivered as a Spherical Harmonics Gravity ASCII Data Record (SHGADR) and is produced by the JPL Dawn Gravity Science Team (Alex Konopliv, Ryan Park, Sami Asmar)." START_ORBIT_NUMBER = 1 STOP_ORBIT_NUMBER = NULL START_TIME = 2015-02-02T07:00:00.000 STOP_TIME = 2018-10-31T10:00:00.000 PRODUCT_CREATION_TIME = 2019-04-04T00:00:00.000 PRODUCER_FULL_NAME = "ALEX S. KONOPLIV" PRODUCER_INSTITUTION_NAME = "JET PROPULSION LABORATORY" PRODUCT_VERSION_TYPE = "FINAL" PRODUCER_ID = "DAWN RADIO SCIENCE" 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 = 2555 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