PDS_VERSION_ID = PDS3 /* label standards identifiers PDS Version 3.8 */ /* File Characteristics */ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 50 FILE_RECORDS = 11798 MD5_CHECKSUM = "17bce5b827fa4e4adf7dfdc486b55d61" /* Pointers to Data Objects */ ^TABLE = "GRD-L1B-180416-180515_181112-CTI-BGOC.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 TRANSFER TO INTERMEDIATE (CTI)" 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-180416-180515_181112-CTI-BGOC" PRODUCT_TYPE = "DATA" PRODUCT_VERSION_ID = "1.0" START_TIME = 2018-04-16T20:32:41 STOP_TIME = 2018-05-15T12:56:11 SPACECRAFT_CLOCK_START_COUNT = "0577182935.000" SPACECRAFT_CLOCK_STOP_COUNT = "0579661145.000" PRODUCT_CREATION_TIME = 2018-11-12T22:01:13 SPICE_FILE_NAME = ("naif0012.tls", "dawn_203_sclkscet.00091.tsc") /* Data Object Definitions */ OBJECT = TABLE ROWS = 11798 ROW_BYTES = 6188 COLUMNS = 4 INTERCHANGE_FORMAT = ASCII DESCRIPTION =" This data file contains a time series of corrected and calibrated pulse height spectra measured by GRaND's bismuth germanate (BGO) scintillator during Ceres encounter. Each row contains the spacecraft clock (SCLK) ticks and spacecraft event UTC time (SCET_UTC) corresponding to the end of the science accumulation interval (accurate to 1s). The ephemeris time for the midpoint of the science interval is also included. Each row also contains the corresponding 1024-channel BGO spectrum accumulated. Each spectrum has been subjected to the following corrections: - Removal of analog-to-digital (ADC) differential nonlinearity artifacts - Gain and offset correction to put each spectrum on the same pulse height For each channel, the corresponding mid-point pulse height can be determined by multiplying channel index (0-1023) by 8.9 keV/channel. The processing steps, including criteria for including spectra in the time series, are described by Yamashita and Prettyman, 'Dawn's Gamma Ray and Neutron Detector: BGO Data Processing', which can be found in the DOCUMENTS directory of this archive. Each record in this file can be matched to a record in the Ephemerides, Pointing, and Geometry (EPG) data file using the 9 digit SCLK code. The EPG file contains additional information needed for analysis and mapping, including the measurement time, spacecraft pointing and position, the solid angle of Ceres, instrument state information, and a proxy for galactic cosmic ray counting rates. " 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 of the 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 = "BGOC" DATA_TYPE = ASCII_INTEGER UNIT = "COUNTS" START_BYTE = 43 BYTES = 6144 ITEMS = 1024 ITEM_BYTES = 6 FORMAT = "I6" DESCRIPTION = " 1024-channel, calibrated BGO spectrum. The pulse height of each channel I=0,1023 is given by 8.9 x I with units of keV. " END_OBJECT = COLUMN END_OBJECT = TABLE END