urn:nasa:pds:mess_grs_raw:data_edr:grs_scr2015114zzz_dat 1.0 1.10.1.0 Product_Observational 2018-06-08 1.0 PDS4 migrated product 2015-04-24T00:13:49.000Z 2015-04-24T23:45:48.000Z 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 5 2/072158419 2/072243138 grs_shield_counter pipe-grs2edr 1.1 acs grs_scr2015114zzz.dat 2015-04-27T04:49:28Z 0 751 This table contains one set of high-time-resolution count rate measurements in the GRS anti-coincidence shield. Each entry contains a 16384-channel-long 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. When the number of measurements exceeds 16384, the last channel records the sum of all subsequent events. A set is defined as all data with MET timestamps corresponding to a given day. 9 1 32792 met 1 1 UnsignedMSB4 4 Mission elapsed time, in seconds, corresponding to the start of the accumulation period for the spectra. accum_time 2 5 UnsignedMSB4 4 Accumulation time, in seconds, of the anti-coincidence shield detector. midpoint_met 3 9 UnsignedMSB4 4 The mission elapsed time at the midpoint of the observation. Defined as: MET at the start of the observation + (ACCUM_TIME / 2). orbit_number 4 13 UnsignedMSB2 2 Orbit number is a unique identifier for a given orbit of the MESSENGER spacecraft 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 5 15 UnsignedMSB2 2 The bin containing first shield counter (starting from zero). Nominally is zero. number_of_bins 6 17 UnsignedMSB2 2 Number of bins in each science packet. grs_priority_level 7 19 UnsignedMSB2 2 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. missing_data_packets 8 21 UnsignedMSB2 2 The value represents a 16-bit binary number where each bit indicates whether a shield count rate telemetry packet is missing from the EDR. Each GRS_SCR EDR consists of information extracted from 16 telemetry packets in a complete observation. The least significant bit is a flag corresponding to the first of 16 packets and the most significant bit is a flag corresponding to the 16th packet. A bit value of 1 indicates that a given packet is missing from the EDR. For example, a value of 0 in this column indicates that the spectra from all 16 packets have been downloaded and included in the count rate spectra for this EDR. A value of 3 indicates that the count rate information from the first and second packets are missing and therefore channels 0-2047 should be discounted from analysis of the GRS_SCR spectra. A value of three or greater would indicate the EDR contains no valid data, since the count rates are only contained in the first 2000 channels. bad_data_flag 9 23 UnsignedMSB2 2 Intended for use as a bit-string bad data flag to indicate specific problems associated with the data. Values are expected to be assigned to specific bits as problems are identified during the course of the mission. Currently no values have been assigned and will default to a value of zero. 1 16384 1 0 25 32768 shield_count_spectra 1 1 UnsignedMSB2 2 High-time-resolution counter of the total event rate in the shield detector. Counter operates at a 10-ms cadence for the duration of the accumulation period, resulting in a series of measurements that populate the 16384 channel spectra. 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. The use of a 16384-channel array is the result of a flight software change to retask a defunct GRS packet into a shield rate counter without changing the format of the packet itself. grs_scr2015114zzz.lbl 0 PDS3 Original PDS3 label Carriage-Return Line-Feed