urn:nasa:pds:mess_grs_derived:data_cdr:grs_csc2014246zzz_tab 1.0 1.10.1.0 Product_Observational 2018-07-03 1.0 PDS4 migrated product. 2014-09-03T00:15:43Z 2014-09-03T23:52:13Z MESSENGER Mission urn:nasa:pds:context:investigation:mission.messenger data_to_investigation MESSENGER Spacecraft urn:nasa:pds:context:instrument_host:spacecraft.mess is_instrument_host Gamma Ray Spectrometer Instrument urn:nasa:pds:context:instrument:grs.mess is_instrument Mercury Planet urn:nasa:pds:context:target:planet.mercury data_to_target Mercury Orbit Year 4 2/052027342 2/052112332 grs_cal_scr grsedr2cdr 3.0 acs grs_csc2014246zzz.tab 2015-10-20T19:36:12Z 0 948 This table contains one set of calibrated high-time-resolution count rate measurements in the GRS anti-coincidence shield. Each entry contains an array that is populated with values corresponding to the total number of events registered by the GRS Anti-Coincidence Shield (ACS) in 10-ms-long increments. When the accumulation period is insufficient to populate all 16384 channels, the remaining entries are assigned values of zero. For arrays exceeding 16384 entries in length, the final channel records the sum of all subsequent entries. A set is defined as all data with MET timestamps corresponding to a given day. Additional details are contained in the CDR-RDR-DAP SIS document. Carriage-Return Line-Feed 29 3 98707 j2000_et 1 1 ASCII_Real 16 Ephemeris time converted from MESSENGER MET. jday 2 17 ASCII_Real 16 Julian date at the start of the time period of interest. Julian date is defined as an integer count of days elapsed since noon, January 1, 4713 B.C. The value includes the fractional portion of the Julian day. met 3 33 ASCII_Integer 13 Mission elapsed time in seconds. accum_time 4 46 ASCII_Integer 13 The time period over which the rates were accumulated. deadtime_frac 5 59 ASCII_Real 13 The fraction of time for which the detector was insensitive to events due to electronics processing of prior events. orbit_number 6 72 ASCII_Integer 6 Unique identifier for a given orbit of MESSENGER around Mercury. Orbit number is defined as starting at apoherm and is calculated using the MET value and the appropriate SPICE kernels. Orbit numbering does not start until MESSENGER performs the Mercury orbit insertion. Until that time the value for orbit number is 0. start_bin 7 78 ASCII_Integer 6 Starting bin for the Shield Count Rate measurements. Initially values may be zero due to detector electronics deadtime. number_of_bins 8 84 ASCII_Integer 6 Number of bins in the shield spectra. grs_priority_level 9 90 ASCII_Integer 6 Indicates the type of priority assigned to the science packet. The priority level is tied to the ApID of the packet. Priority level varies from 0-3, 0 being highest and 3 being lowest priority. bad_data_flag 10 96 ASCII_Integer 6 Values of 1 indicate that the data quality is poor, for example increased backgrounds due to solar particle events, or that the detector was not operating nominally, for example the bias voltage was off. Values of 0 indicate that the data are clean and suited for analysis. triple 11 102 ASCII_Real 13 Triple coincidence count rate in the MESSENGER Neutron Spectrometer. This value is a known proxy for the spacecraft-incident galactic cosmic ray flux. preamp_temp 12 115 ASCII_Real 13 Temperature of the pre-amplifier. shld_chrg_rset_1sec 13 128 ASCII_Real 13 Hardware Shield charge reset 1-second total. shaper_temp 14 141 ASCII_Real 13 Shaper Temperature. altitude 15 154 ASCII_Real 10 Spacecraft altitude above the subsatellite point on the target in units of km. latitude 16 164 ASCII_Real 9 Target-centric latitude of the spacecraft subsatellite point in degrees. longitude 17 173 ASCII_Real 9 Target-centric longitude of the spacecraft subsatellite point in degrees. local_time 18 182 ASCII_Real 9 Local time of the spacecraft subsatellite point in hours from 0 to 24. 1 3 1 0 191 27 velocity_vector 1 1 ASCII_Real 9 Three element spacecraft velocity vector expressed in the nadir-fixed coordinate system with each component in units of km/second. vel_norm 19 218 ASCII_Real 9 Magnitude of the spacecraft velocity as expressed in the nadir-fixed coordinate system in units of km/second. 2 9 1 0 227 81 sc_to_nadir_rot 1 1 ASCII_Real 9 Nine element rotation matrix that converts the spacecraft attitude from instrument-fixed coordinates to nadir-fixed coordinates. vdot_x 20 308 ASCII_Real 9 Velocity normalized dot product of the vector velocity and the spacecraft x-axis unit vector expressed as a unitless number from -1 to 1. vdot_y 21 317 ASCII_Real 9 Velocity normalized dot product of the vector velocity and the spacecraft y-axis unit vector expressed as a unitless number from -1 to 1. vdot_z 22 326 ASCII_Real 9 Velocity normalized dot product of the vector velocity and the spacecraft z-axis unit vector expressed as a unitless number from -1 to 1. nadir_angle 23 335 ASCII_Real 9 Spacecraft orientation angle of the spacecraft z-axis and the spacecraft-to-planet center vector in units of degrees. yaxis_angle 24 344 ASCII_Real 9 Spacecraft orientation angle of the spacecraft y-axis and the spacecraft-to-planet center vector in units of degrees. xaxis_angle 25 353 ASCII_Real 9 Spacecraft orientation angle of the spacecraft x-axis and the spacecraft-to-planet center vector in units of degrees. theta_angle 26 362 ASCII_Real 9 Polar angle look direction (in a theta,phi spherical geometry) of the spacecraft in the spacecraft-fixed coordinate system. THETA_ANGLE = 0 degrees is when the spacecraft z-axis points in the same direction as the spacecraft-to-planet center vector (nadir pointing). phi_angle 27 371 ASCII_Real 9 Azimuthal angle look direction (in a theta,phi spherical geometry) of the spacecraft in the spacecraft-fixed coordinate system. PHI_ANGLE = 0 degrees is when the spacecraft x-axis points along the direction of travel. beta_angle 28 380 ASCII_Real 9 Angle of the normal of the spacecraft orbital plane with respect to Mercury-to-Sun vector in degrees. sun_distance 29 389 ASCII_Real 13 Distance of the spacecraft to the Sun in units of km. 3 16384 1 0 402 98304 shield_count_spectra 1 1 ASCII_Integer 6 High-time-resolution counter of the total event rate in the shield detector. Counter operates at a 10ms cadence for the duration of the accumulation period, resulting in a series of measurements that populate the 16384 channel spectrum. When fewer than 16384 channels are required, the remainder are set to zero. When more than 16384 channels are required, the last channel represents the sum of all measurements made after the array is filled. For all cases, the first approximately fifty channels are zero due to signal processing deadtime in the GRS electronics. grs_csc2014246zzz.lbl 0 PDS3 Original PDS3 label Carriage-Return Line-Feed