PDS_VERSION_ID = PDS3 /* label standards identifiers PDS Version 3.8 */ /* File Characteristics */ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 221 FILE_RECORDS = 575770 MD5_CHECKSUM = "46a0ad09ef5abc14e6a7f613ac61063e" /* Pointers to Data Objects */ ^TABLE = "GRD-L1B-150313-181026_190117-EPG.TAB" PRODUCER_FULL_NAME = "T. H. Prettyman" PRODUCER_INSTITUTION_NAME = "PLANETARY SCIENCE INSTITUTE" /* Identification Data Elements */ MISSION_NAME = "DAWN MISSION TO VESTA AND CERES" MISSION_ID = "DAWN" MISSION_PHASE_NAME = { "CERES SCIENCE APPROACH (CSA)", "CERES SCIENCE RC3 (CSR)", "CERES TRANSFER TO SURVEY (CTS)", "CERES SCIENCE SURVEY (CSS)", "CERES TRANSFER TO HAMO (CTH)", "CERES SCIENCE HAMO (CSH)", "CERES TRANSFER TO LAMO (CTL)", "CERES SCIENCE LAMO (CSL)", "CERES EXTENDED LAMO (CXL)", "CERES TRANSFER TO JULING (CTJ)", "CERES EXTENDED JULING (CXJ)", "CERES TRANSFER TO GRAND (CTG)", "CERES EXTENDED GRAND (CXG)", "CERES TRANSFER TO OPPOSITION (CTO)", "CERES EXTENDED OPPOSITION (CXO)", "CERES EXTENDED MISSION 2 (CX2)", "CERES X2 TRANSFER TO INTERMEDIATE (CTI)", "CERES X2 INTERMEDIATE (C2I)", "CERES X2 TRANSFER TO ELLIPTICAL (CTE)", "CERES X2 ELLIPTICAL (C2E)"} TARGET_NAME = "1 CERES" TARGET_TYPE = "ASTEROID" INSTRUMENT_HOST_NAME = "DAWN" INSTRUMENT_HOST_ID = "DAWN" INSTRUMENT_ID = "GRAND" INSTRUMENT_NAME = "GAMMA-RAY AND NEUTRON DETECTOR" DATA_SET_ID = "DAWN-A-GRAND-3-RDR-CERES-COUNTS-V1.0" DATA_SET_NAME = "DAWN GRAND CALIBRATED (RDR) CERES COUNTS V1.0" PRODUCT_ID = "GRD-L1B-150313-181026_190117-EPG" PRODUCT_TYPE = "DATA" PRODUCT_VERSION_ID = "1.0" START_TIME = 2015-03-13T03:22:36 STOP_TIME = 2018-10-26T06:05:18 SPACECRAFT_CLOCK_START_COUNT = "0479489128.000" SPACECRAFT_CLOCK_STOP_COUNT = "0593806214.000" PRODUCT_CREATION_TIME = 2019-01-17T01:34:24 SPICE_FILE_NAME = ("naif0012.tls", "dawn_203_sclkscet.00091.tsc", "dawn_ceres_v00.tf", "dawn_v14.tf", "dawn_ceres_grv171219_v1.tpc", "dawn_grand_v00.ti", "de432.bsp", "sb_ceres_grv_171219.bsp", "dawn_rec_141230-150509_150603_v1.bsp", "dawn_rec_150509-150630_150730_v1.bsp", "dawn_rec_150630-151023_160804_v1.bsp", "dawn_rec_151023-160202_160412_v1.bsp", "dawn_rec_160202-160319_160531_v1.bsp", "dawn_rec_160319-160410_160809_v1.bsp", "dawn_rec_160410-160505_160809_v1.bsp", "dawn_rec_160505-160527_160810_v1.bsp", 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"dawn_sc_160411_160417.bc", "dawn_sc_160418_160424.bc", "dawn_sc_160425_160501.bc", "dawn_sc_160502_160508.bc", "dawn_sc_160509_160515.bc", "dawn_sc_160516_160522.bc", "dawn_sc_160523_160529.bc", "dawn_sc_160530_160605.bc", "dawn_sc_160606_160612.bc", "dawn_sc_160613_160619.bc", "dawn_sc_160620_160626.bc", "dawn_sc_160627_160703.bc", "dawn_sc_160704_160710.bc", "dawn_sc_160711_160717.bc", "dawn_sc_160718_160724.bc", "dawn_sc_160725_160731.bc", "dawn_sc_160801_160807.bc", "dawn_sc_160808_160814.bc", "dawn_sc_160815_160821.bc", "dawn_sc_160822_160828.bc", "dawn_sc_160829_160904.bc", "dawn_sc_160905_160911.bc", "dawn_sc_160912_160918.bc", "dawn_sc_160919_160925.bc", "dawn_sc_160926_161002.bc", "dawn_sc_161003_161009.bc", "dawn_sc_161010_161016.bc", "dawn_sc_161017_161023.bc", "dawn_sc_161024_161030.bc", "dawn_sc_161031_161106.bc", "dawn_sc_161107_161113.bc", "dawn_sc_161114_161120.bc", "dawn_sc_161121_161127.bc", "dawn_sc_161128_161204.bc", "dawn_sc_161205_161211.bc", "dawn_sc_161212_161218.bc", "dawn_sc_161219_161225.bc", "dawn_sc_161226_170101.bc", "dawn_sc_170102_170108.bc", "dawn_sc_170109_170115.bc", "dawn_sc_170116_170122.bc", "dawn_sc_170123_170129.bc", "dawn_sc_170130_170205.bc", "dawn_sc_170206_170212.bc", "dawn_sc_170213_170219.bc", "dawn_sc_170220_170226.bc", "dawn_sc_170227_170305.bc", "dawn_sc_170306_170312.bc", "dawn_sc_170313_170319.bc", "dawn_sc_170320_170326.bc", "dawn_sc_170327_170402.bc", "dawn_sc_170403_170409.bc", "dawn_sc_170410_170416.bc", "dawn_sc_170417_170423.bc", "dawn_sc_170424_170430.bc", "dawn_sc_170501_170507.bc", "dawn_sc_170508_170514.bc", "dawn_sc_170515_170521.bc", "dawn_sc_170522_170528.bc", "dawn_sc_170529_170604.bc", "dawn_sc_170605_170611.bc", "dawn_sc_170612_170618.bc", "dawn_sc_170619_170625.bc", "dawn_sc_170626_170702.bc", "dawn_sc_170703_170709.bc", "dawn_sc_170710_170716.bc", "dawn_sc_170717_170723.bc", "dawn_sc_170724_170730.bc", "dawn_sc_170731_170806.bc", "dawn_sc_170807_170813.bc", "dawn_sc_170814_170820.bc", "dawn_sc_170821_170827.bc", "dawn_sc_170828_170903.bc", "dawn_sc_170904_170910.bc", "dawn_sc_170911_170917.bc", "dawn_sc_170918_170924.bc", "dawn_sc_170925_171001.bc", "dawn_sc_171002_171008.bc", "dawn_sc_171009_171015.bc", "dawn_sc_171016_171022.bc", "dawn_sc_171023_171029.bc", "dawn_sc_171030_171105.bc", "dawn_sc_171106_171112.bc", "dawn_sc_171113_171119.bc", "dawn_sc_171120_171126.bc", "dawn_sc_171127_171203.bc", "dawn_sc_171204_171210.bc", "dawn_sc_171211_171217.bc", "dawn_sc_171218_171224.bc", "dawn_sc_171225_171231.bc", "dawn_sc_180101_180107.bc", "dawn_sc_180108_180114.bc", "dawn_sc_180115_180121.bc", "dawn_sc_180122_180128.bc", "dawn_sc_180129_180204.bc", "dawn_sc_180205_180211.bc", "dawn_sc_180212_180218.bc", "dawn_sc_180219_180225.bc", "dawn_sc_180226_180304.bc", "dawn_sc_180305_180311.bc", "dawn_sc_180312_180318.bc", "dawn_sc_180319_180325.bc", "dawn_sc_180326_180401.bc", "dawn_sc_180402_180408.bc", "dawn_sc_180409_180415.bc", "dawn_sc_180416_180422.bc", "dawn_sc_180423_180429.bc", "dawn_sc_180430_180506.bc", "dawn_sc_180507_180513.bc", "dawn_sc_180514_180520.bc", "dawn_sc_180521_180527.bc", "dawn_sc_180528_180603.bc", "dawn_sc_180604_180610.bc", "dawn_sc_180611_180617.bc", "dawn_sc_180618_180624.bc", "dawn_sc_180625_180701.bc", "dawn_sc_180702_180708.bc", "dawn_sc_180709_180715.bc", "dawn_sc_180716_180722.bc", "dawn_sc_180723_180729.bc", "dawn_sc_180730_180805.bc", "dawn_sc_180806_180812.bc", "dawn_sc_180813_180819.bc", "dawn_sc_180820_180826.bc", "dawn_sc_180827_180902.bc", "dawn_sc_180903_180909.bc", "dawn_sc_180910_180916.bc", "dawn_sc_180917_180923.bc", "dawn_sc_180924_180930.bc", "dawn_sc_181001_181007.bc", "dawn_sc_181008_181014.bc", "dawn_sc_181015_181021.bc", "dawn_sc_181022_181028.bc") /* Data Object Definitions */ OBJECT = TABLE ROWS = 575770 ROW_BYTES = 221 COLUMNS = 21 INTERCHANGE_FORMAT = ASCII DESCRIPTION =" This time series data set contains ephemeris, pointing and geometry (EPG) data for the GRaND instrument during Ceres encounter. The spacecraft position is in the Ceres fixed frame. The direction to body center is in the spacecraft frame. The spacecraft clock ticks (SCLK), which mark the end of each accumulation interval are provided for each science data record. SCLK marks the end of the science accumulation interval with 1s precision and is used to calculate the mid-point ephemeris time, which is presented in UTC time format and in seconds. SCLK also serves as a 9-digit serial code that uniquely identifies each science data record. GRaND L1A and L1B science data files include SCLK as an identifier, such that values for the same record can be easily extracted from different tables. The position, direction to body center, and solid angle values are referenced to the midpoint of the accumulation interval, which is TELREADOUT (s)long. The live time (LIVE_TIME) is the amount of time during the accumulation interval that the instrument was available to process events. Unbiased counting rates can be determined by dividing counts by LIVE_TIME. The measurement geometry is determined by the solid angle subtended by Ceres at the spacecraft (with units of steradians). Counting rates, with background contributions removed, vary in proportion to the solid angle. Thus, the solid angle values can be used to eliminate measurement geometry effects to reveal compositional variations on the surface of Ceres. SOLID_ANGLE was determined using the methods described by PRETTYMANETAL2011 and PRETTYMANETAL2012 using a Digital Terrain Model provided by the Dawn navigation team (CERES_SURVEY_150716_GRAVITY_SPC). The interconnected quadrilateral (ICQ) format was converted to a triangle-vertex model, which was decimated, retaining 1% of the triangles. The decimated shape model used for the solid angle calculation is provided in EXTRAS in STereoLithography (STL) format (binary) and as a Type 1 triangle-vertex file (ascii). The spacecraft EQUIVALENT_ALTITUDE (km) was also determined for each science accumulation interval from SOLID_ANGLE. The EQUIVALENT_ALTITUDE is the distance from a sphere of the same volume as Ceres (with a radius, R_EQ of 469.8km) that gives the same SOLID_ANGLE as determined from the shape model: EQUIVALENT_ALTITUDE = R_EQ / sqrt{ 1 - [ 1 - SOLID_ANGLE/(2*PI) ]^2} - R_EQ The subsatellite distance (SUBSAT_DIST), which is the distance from the spacecraft to the surface of the shape model in the direction of body center, is also provided. The triples and higher-order coincidence counting rate (TRIPLES_RATE) is provided for each science accumulation interval for which associated state-of-health packets (SOH) can be identified. TRIPLES_RATE is a proxy for the interaction rate of galactic cosmic rays (GCR) with the instrument and can be used to correct for temporal variations in gamma ray and neutron production within the regolith of Ceres. Large deviations from the local mean of the time series may be due to solar energetic particle events, cycling of the instrument state (e.g. power-on and HV ramp up), or other conditions. No attempt has been made to remove corrupt or anomalous data. See grand_l1a_ceres_ds.cat for a description of data quality and coverage for counting products. During Ceres encounter, different instrument settings (states) were used to acquire science data. An instrument configuration index (INSTR_CONFIG) is provided to indicate operational state. Allowed values include: INSTR_CONFIG=0: The instrument was not fully configured for science data acquisition. INSTR_CONFIG>0: The instrument was fully configured. INSTR_CONFIG indicates the combination of high voltage settings that were used. High voltage setting (data number, DN) INSTR_CONFIG HV1 HV2 HV3 HV4 HV5 HV6 1 180 170 175 180 125 170 2 185 170 175 180 125 170 3 180 170 175 180 127 170 4 185 173 178 182 127 170 5 185 173 178 182 123 170 6 180 170 175 180 119 170 7 180 170 175 180 121 170 8 180 170 175 180 123 170 9 180 170 175 180 128 170 10 185 173 178 182 121 170 11 185 173 178 182 119 170 (Note: 1500 V per 255 DN) Finally, the average BGO temperature (T_BGO) is provided for most science accumulation intervals. The BGO temperature data is useful for idenfiying times when GRaND�s internal temperatures have stabilized following power on. The sensor is well isolated with a thermal time constant of about 24 hours. Values for LIVE_TIME, TRIPLES, and T_BGO are provided for science records for which the associated SOH packets can be identified. Otherwise, a MISSING_CONSTANT is listed. More detail about the methods used to develop this data product and their validation can be found in GRD_L1B_Ephemeris_Pointing_Geometry_v1.pdf, which is included in the DOCUMENTS directory. " OBJECT = COLUMN NAME = "SCLK" DATA_TYPE = ASCII_INTEGER UNIT = SECONDS START_BYTE = 1 BYTES = 10 FORMAT = "I10" DESCRIPTION = " SCLK ticks at the end of the science accumulation interval (s) Each science data record has a unique SCLK value, which can be used as an identifier. " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "SCET_UTC" DATA_TYPE = TIME UNIT = "N/A" START_BYTE = 11 BYTES = 20 FORMAT = "A20" DESCRIPTION = " UTC S/C event time (SCET) at the midpoint ofthe science accumulation interval. " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "ET_MID" DATA_TYPE = ASCII_REAL UNIT = "SECONDS" START_BYTE = 31 BYTES = 12 FORMAT = "F12.1" DESCRIPTION = " Ephemeris time at the midpoint of the science accumulation interval (s). " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "PHASE" DATA_TYPE = CHARACTER UNIT = "N/A" START_BYTE = 43 BYTES = 4 FORMAT = "A4" DESCRIPTION = " Abbreviation for the mission phase. See dawnmission.cat for definitions of mission phases. " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "TELREADOUT" DATA_TYPE = ASCII_INTEGER UNIT = "SECONDS" START_BYTE = 47 BYTES = 5 FORMAT = "I5" DESCRIPTION = " Length of the accumulation interval (s) " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "LIVE_TIME" DATA_TYPE = ASCII_REAL UNIT = "SECONDS" START_BYTE = 52 BYTES = 8 FORMAT = "F8.2" MISSING_CONSTANT = -999.00 DESCRIPTION = " Live time (s). " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "LON" DATA_TYPE = ASCII_REAL UNIT = "DEG" START_BYTE = 60 BYTES = 8 FORMAT = "F8.2" DESCRIPTION = " Spacecraft longitude. " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "LAT" DATA_TYPE = ASCII_REAL UNIT = "DEG" START_BYTE = 68 BYTES = 8 FORMAT = "F8.2" DESCRIPTION = " Spacecraft latitude. " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "DIST" DATA_TYPE = ASCII_REAL UNIT = "KM" START_BYTE = 76 BYTES = 12 FORMAT = "F12.2" DESCRIPTION = " Distance from the spacecraft to body center. " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "POS_X" DATA_TYPE = ASCII_REAL UNIT = "KM" START_BYTE = 88 BYTES = 12 FORMAT = "F12.2" DESCRIPTION = " Spacecraft position (X). " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "POS_Y" DATA_TYPE = ASCII_REAL UNIT = "KM" START_BYTE = 100 BYTES = 12 FORMAT = "F12.2" DESCRIPTION = " Spacecraft position (Y). " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "POS_Z" DATA_TYPE = ASCII_REAL UNIT = "KM" START_BYTE = 112 BYTES = 12 FORMAT = "F12.2" DESCRIPTION = " Spacecraft position (Z). " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "DIR_U" DATA_TYPE = ASCII_REAL UNIT = "UNITLESS" START_BYTE = 124 BYTES = 13 FORMAT = "E13.4" DESCRIPTION = " Body-center direction in S/C frame (x cosine). " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "DIR_V" DATA_TYPE = ASCII_REAL UNIT = "UNITLESS" START_BYTE = 137 BYTES = 13 FORMAT = "E13.4" DESCRIPTION = " Body-center direction in S/C frame (y cosine). " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "DIR_W" DATA_TYPE = ASCII_REAL UNIT = "UNITLESS" START_BYTE = 150 BYTES = 13 FORMAT = "E13.4" DESCRIPTION = " Body-center direction in S/C frame (z cosine). " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "SOLID_ANGLE" DATA_TYPE = ASCII_REAL UNIT = "STERADIANS" START_BYTE = 163 BYTES = 11 FORMAT = "E11.3" DESCRIPTION = " Solid angle subtended by Ceres at the spacecraft. " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "EQUIVALENT_ALTITUDE" DATA_TYPE = ASCII_REAL UNIT = "KM" START_BYTE = 174 BYTES = 12 FORMAT = "F12.2" DESCRIPTION = " Equivalent altitude of the spacecraft if Ceres were a sphere of 469.7 km radius. Calculated from the solid angle. " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "SUBSAT_DIST" DATA_TYPE = ASCII_REAL UNIT = "KM" START_BYTE = 186 BYTES = 12 FORMAT = "F12.2" DESCRIPTION = " Distance to the sub-satellite point in the body-center direction. " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "TRIPLES_RATE" DATA_TYPE = ASCII_REAL UNIT = "COUNTS PER SECOND" START_BYTE = 198 BYTES = 9 FORMAT = "F9.2" MISSING_CONSTANT = -999.00 DESCRIPTION = " Counting rate for coincidences between three or more sensors, used as a proxy for the galactic cosmic ray flux. " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "INSTR_CONFIG" DATA_TYPE = ASCII_INTEGER UNIT = "N/A" START_BYTE = 207 BYTES = 4 FORMAT = "I4" DESCRIPTION = " Instrument configuration: If 0, the instrument was not fully configured for science data acquisition; if greater than 0, then the instrument was fully configured. The instrument configuration indicates the combination of high voltage settings used. For a complete list, see Data Objects Definitions in this label file. " END_OBJECT = COLUMN OBJECT = COLUMN NAME = "T_BGO" DATA_TYPE = ASCII_REAL UNIT = "CELSIUS" START_BYTE = 211 BYTES = 9 FORMAT = "F9.2" MISSING_CONSTANT = -999.00 DESCRIPTION = " BGO temperature reading averaged over the science accumulation interval. " END_OBJECT = COLUMN END_OBJECT = TABLE 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 END