urn:nasa:pds:izenberg_pdart14_meap:data_grsspectra:grs_rac2011237zzz 1.0 1.11.0.0 Product_Observational 2018-06-06 1.0 Izenberg PDART 2014 MEAP Enhanced Gamma Ray Spectrometry Data. 2011-08-25T00:07:12.555Z 2011-08-25T23:47:18.557Z Science Derived A recently developed algorithm was used to characterize the quality of the MESSENGER Gamma-Ray Spectrometer (GRS) orbital measurements, information that can be used to greatly increase the total quantity of high quality gamma-ray spectra useable for examining Mercury's surface composition. See description of field "LE_COUNT_RATE" for details. MESSENGER Mission urn:nasa:pds:context:investigation:mission.messenger data_to_investigation MESSENGER MESSENGER Spacecraft urn:nasa:pds:context:instrument_host:spacecraft.mess is_instrument_host GRS Instrument urn:nasa:pds:context:instrument:grs.mess is_instrument Mercury Planet urn:nasa:pds:context:target:planet.mercury collection_to_target 10.1016/j.icarus.2017.01.022 Evans, L.G., Peplowski, P.N., Rhodes, E.A., Goldsten, J.O., Starr, R.D. and Solomon, S.C., 2017. The MESSENGER Gamma-Ray Spectrometer: Calibration and operations. Icarus, 288, pp.186-200. 10.1029/2012JE004141 Peplowski, P.N., Lawrence, D.J., Rhodes, E.A., Sprague, A.L., McCoy, T.J., Denevi, B.W., Evans, L.G., Head, J.W., Nittler, L.R., Solomon, S.C. and Stockstill-Cahill, K.R., 2012. Variations in the abundances of potassium and thorium on the surface of Mercury: Results from the MESSENGER Gamma-Ray Spectrometer. Journal of Geophysical Research: Planets, 117(E12). grs_rac2011237zzz.dat 2018-09-21T14:00:37.743Z 19487160 Mercury Enhanced Gamma Ray Spectrometry Data 0 296 61 1 65835 MET 1 1 UnsignedMSB4 4 s Mission elapsed time, in seconds, corresponding to the start of the accumulation period for the spectra. ACCUM_TIME 2 5 UnsignedMSB4 4 s Accumulation time, in seconds, of the HPGe detector. MIDPOINT_MET 3 9 UnsignedMSB4 4 s The mission elapsed time at the midpoint of the HPGE Raw 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 Start Bin of the HPGe detector. NUMBER_OF_BINS 6 17 UnsignedMSB2 2 Number of bins in the raw spectra. 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 an HPGe Raw telemetry packet is missing from the EDR. Each HPGe Raw 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 HPGE_RAW spectra for this EDR. A value of 3 indicates that the spectra information from the first and second packets are missing and therefore spectral bins 0-2047 should be discounted from analysis of the HPGE_RAW spectra. 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. Bit 1 - The high voltage is not on, is being ramped or has not been stable long enough. Bit 2 - Indicates a change in the analog pulse processing system gain setting. Bit 3 - Indicates a spectrum where the temperatures used for correction have fluctuated by greater than 5 percent from previous readings. Bit 4 - Indicates gamma spectra collected during a solar particle event. These spectra should not be combined with spectra collected under normal solar conditions. Bit 5 - Pulser data is not combined with the spectrum. Bit 6 - Indicates gamma spectra collected during a solar flare event. These spectra should not be combined with spectra collected under normal solar conditions. Bit 7 - Indicates gamma spectra collected during periods of decreased GS detector spectral resolution. These spectra should not be combined with spectra collected under 'normal' detector conditions. Bit 8 - Not all data channels were received on the ground. Bit 9 - Indicates a unique problem with single spectrum. Bit 10 - The high voltage has not been stable long enough. Bit 11 - This data was taken during a time when the spectra were particularly noisy. Many channels have far too many counts, especially the lower channels. LE_COUNT_RATE 10 25 IEEE754MSBSingle 4 Number of events in the spectrum with energy less than 50 keV, in units of counts per second (cps). This value was calculated by summing the number of events in the energy range and dividing by the live time of the measurement. Live time calculations are discussed in Peplowski et al. (2012). LE_COUNT_RATE is a proxy for low-energy noise present in the GRS measurements (Evans et al., 2017), a problem that started on 11 October 2012 and that resulted in degradation of the energy resolution of the GRS measurements. LE_COUNT_RATE values >200 cps correspond to significantly degraded performance, lower values are considered acceptable for science analysis. 16384 1 0 29 65536 CAL_AC 1 1 IEEE754MSBSingle 4 Anti-coincident (AC) spectra accumulated by the HPGe detector. Contains the corrected counts in each of the 16384 bins after 1 accumulation period. UTC_MIDPOINT_MET_DATE 11 65565 ASCII_Date_YMD 10 MIDPOINT_MET converted to UTC Date, stored as yyyy-mm-dd Blank_1 12 65575 ASCII_String 1 blank UTC_MIDPOINT_MET_TIME 13 65576 ASCII_Time 12 MIDPOINT_MET converted to UTC Time, stored as hh:mm:ss.sss MERCURY_CENTRIC_LATITUDE 14 65588 IEEE754MSBDouble 8 deg Sub spacecraft latitude in Mercury fixed coordinates at the middle of the collection interval. MERCURY_CENTRIC_LONGITUDE 15 65596 IEEE754MSBDouble 8 deg Sub spacecraft longitude in Mercury fixed coordinates at the middle of the collection interval. Longitude increases towards the East. INSTR_BORESIGHT_MERCURY_X 16 65604 IEEE754MSBDouble 8 km Sub instrument boresight (x component) in Mercury fixed coordinates at the middle of the collection interval. INSTR_BORESIGHT_MERCURY_Y 17 65612 IEEE754MSBDouble 8 km Sub instrument boresight (y component) in Mercury fixed coordinates at the middle of the collection interval. INSTR_BORESIGHT_MERCURY_Z 18 65620 IEEE754MSBDouble 8 km Sub instrument boresight (z component) in Mercury fixed coordinates at the middle of the collection interval. SCALT 19 65628 IEEE754MSBDouble 8 km Mercury centric altitude of the sub-spacecraft point in Mercury-fixed rotating frame at the middle of the collection interval. DELTA_ANGLE 20 65636 IEEE754MSBDouble 8 deg Difference between instrument +y direction and true north at the middle of the collection interval. MERCURY_SOL 21 65644 IEEE754MSBDouble 8 deg Longitude of the Sun at 0 hours UT on the date of the record. Taken from the Association of Lunar and Planetary Observers 'Ephemeris for Physical Observation of Mercury'. LOCAL_HOUR 22 65652 UnsignedByte 1 hours Local Sun hour at the sub-spacecraft point. LOCAL_MINUTE 23 65653 UnsignedByte 1 minutes Local Sun minute at the sub-spacecraft point. POINTING 24 65654 UnsignedByte 1 1 if pointing data was available. INTERSECTING 25 65655 UnsignedByte 1 1 if the pointing vector intersects Mercury. NADIR_ANGLE 26 65656 IEEE754MSBDouble 8 deg Spacecraft attitude during orbits and flybys is defined by two additional coordinate systems, the GRS LVLH (Local Vertical Local Horizontal) frame and the spacecraft fixed frame, and by the rotation of the spacecraft frame with respect to the GRS LVLH frame. In the GRS LVLH frame, the Z axis is aligned with the vector from the spacecraft to the planet center (the nadir direction), the Y axis is the negative of the cross product of the position and velocity vectors, and the X axis points in the instantaneous direction of motion, completing a right-handed coordinate system. The Z axis is along the viewing direction of the instrument deck inside the adapter ring and of the GRS just outside the adapter ring, the Y axis is directed from the spacecraft along the magnetometer boom, and the X-axis is parallel to the solar panel booms, forming a right-handed coordinate system. The spacecraft attitude is specified by the rotation of the spacecraft fixed frame Z axis in the GRS LVLH frame and a twist angle about the Z axis. The Z axis rotation is given by a nadir angle and an azimuth angle, where the nadir angle is 0 degrees when the spacecraft Z axis points along the + Z LVLH axis and 180 degrees when it points along -Z in the LVLH frame, and the LVLH azimuth angle is measured counterclockwise about the Z LVLH axis from the X LVLH axis. The twist angle is measured positive about the +Z spacecraft axis. See section 5.4.2 in the GRS_CDR_SIS for further details. AZIMUTH 27 65664 IEEE754MSBDouble 8 deg Spacecraft attitude during orbits and flybys is defined by two additional coordinate systems, the GRS LVLH (Local Vertical Local Horizontal) frame and the spacecraft fixed frame, and by the rotation of the spacecraft frame with respect to the GRS LVLH frame. In the GRS LVLH frame, the Z axis is aligned with the vector from the spacecraft to the planet center (the nadir direction), the Y axis is the negative of the cross product of the position and velocity vectors, and the X axis points in the instantaneous direction of motion, completing a right-handed coordinate system. The Z axis is along the viewing direction of the instrument deck inside the adapter ring and of the GRS just outside the adapter ring, the Y axis is directed from the spacecraft along the magnetometer boom, and the X-axis is parallel to the solar panel booms, forming a right-handed coordinate system. The spacecraft attitude is specified by the rotation of the spacecraft fixed frame Z axis in the GRS LVLH frame and a twist angle about the Z axis. The Z axis rotation is given by a nadir angle and an azimuth angle, where the nadir angle is 0 degrees when the spacecraft Z axis points along the + Z LVLH axis and 180 degrees when it points along -Z in the LVLH frame, and the LVLH azimuth angle is measured counterclockwise about the Z LVLH axis from the X LVLH axis. The twist angle is measured positive about the +Z spacecraft axis. See section 5.4.2 in the GRS_CDR_SIS for further details. TWIST_ANGLE 28 65672 IEEE754MSBDouble 8 deg Spacecraft attitude during orbits and flybys is defined by two additional coordinate systems, the GRS LVLH (Local Vertical Local Horizontal) frame and the spacecraft fixed frame, and by the rotation of the spacecraft frame with respect to the GRS LVLH frame. In the GRS LVLH frame, the Z axis is aligned with the vector from the spacecraft to the planet center (the nadir direction), the Y axis is the negative of the cross product of the position and velocity vectors, and the X axis points in the instantaneous direction of motion, completing a right-handed coordinate system. The Z axis is along the viewing direction of the instrument deck inside the adapter ring and of the GRS just outside the adapter ring, the Y axis is directed from the spacecraft along the magnetometer boom, and the X-axis is parallel to the solar panel booms, forming a right-handed coordinate system. The spacecraft attitude is specified by the rotation of the spacecraft fixed frame Z axis in the GRS LVLH frame and a twist angle about the Z axis. The Z axis rotation is given by a nadir angle and an azimuth angle, where the nadir angle is 0 degrees when the spacecraft Z axis points along the + Z LVLH axis and 180 degrees when it points along -Z in the LVLH frame, and the LVLH azimuth angle is measured counterclockwise about the Z LVLH axis from the X LVLH axis. The twist angle is measured positive about the +Z spacecraft axis. See section 5.4.2 in the GRS_CDR_SIS for further details. HPGE_TEMP_1 29 65680 IEEE754MSBDouble 8 degK Channel 00, HPGE Detector Temperature 1, smoothed and interpolated to the center of the collection interval. HPGE_TEMP_2 30 65688 IEEE754MSBDouble 8 degK Channel 01, HPGE Detector Temperature 2, smoothed and interpolated to the center of the collection interval. CALIB_AVG_DET_TEMP 31 65696 IEEE754MSBDouble 8 degK Calibrated, averaged detector temperature, smoothed and interpolated to the center of the collection interval. PREAMP_TEMP 32 65704 IEEE754MSBDouble 8 degC Channel 04, Pre Amp Temperature, smoothed and interpolated to the center of the collection interval. SHAPER_TEMP 33 65712 IEEE754MSBDouble 8 degC Channel 05, Shaper Temperature, smoothed and interpolated to the center of the collection interval. HV_MONITOR 34 65720 IEEE754MSBDouble 8 volts Channel 07, HV Monitor, smoothed and interpolated to the center of the collection interval. HPGE_RAW_EVENTS 35 65728 UnsignedMSB4 4 Counter of HPGe Raw events. SHIELD_RAW_EVENTS 36 65732 UnsignedMSB4 4 Counter for SHIELD raw events. ACCUMULATED_DEAD_TIME 37 65736 UnsignedMSB4 4 Counter for accumulated dead time. HPGE_CHARGE_RESETS 38 65740 UnsignedMSB4 4 Number of HPGe charge resets. SHIELD_CHARGE_RESETS 39 65744 UnsignedMSB4 4 Number of SHIELD charge resets. ALL_EVENTS 40 65748 UnsignedMSB4 4 Total count of gamma events. ALL_CH0_CH1_EVENTS 41 65752 UnsignedMSB4 4 All channel 0 and channel 1 events. Excludes inverted Channel 0, Pileups, and Pulser events. ALL_CH0_EVENTS 42 65756 UnsignedMSB4 4 All single Channel 0 events - either singlet or fails crossing time criterion. ALL_CH1_EVENTS 43 65760 UnsignedMSB4 4 All single Channel 1 events - either singlet or fails crossing time criterion. INVALID_SINGLE_CH0 44 65764 UnsignedMSB4 4 Single channel 0 out-of-range events. INVALID_SINGLE_CH1 45 65768 UnsignedMSB4 4 Single channel 1 out-of-range events. INVALID_COINCIDENT_CH0 46 65772 UnsignedMSB4 4 Channel 0 out-of-range coincidence events. INVALID_COINCIDENT_CH1 47 65776 UnsignedMSB4 4 Channel 1 out-of-range coincidence events. VALID_SINGLE_CH0 48 65780 UnsignedMSB4 4 Single channel 0 valid events only. VALID_COINCIDENT_CH0 49 65784 UnsignedMSB4 4 Coincidence channel 0 valid events. VALID_SINGLE_CH1 50 65788 UnsignedMSB4 4 Single channel 1 valid events only. VALID_COINCIDENT_CH1 51 65792 UnsignedMSB4 4 Coincidence channel 1 valid events. ALL_VALID_COINCIDENT 52 65796 UnsignedMSB4 4 All valid coincidence events - both Channel 0 and Channel 1 valid. INVERTED_CH0 53 65800 UnsignedMSB4 4 Channel 0 events flagged 'inverted' by the hardware. CH0_PILEUP_REJECT 54 65804 UnsignedMSB4 4 Channel 0 pileup rejected events. Only if pileup rejection is enabled. FIFO_FULL_COUNT 55 65808 UnsignedMSB4 4 Hardware FIFO full flag tested for all events. PULSER_ENERGY_SUM 56 65812 UnsignedMSB4 4 Pulser energy sum. Summation of (Pulser Energy - Offset). PULSER_ENERGY_SUM2 57 65816 UnsignedMSB4 4 Pulser energy sum squared. Summation of square of (Pulser Energy - Offset). PULSER_EVENTS 58 65820 UnsignedMSB4 4 Number of valid pulser events. INVALID_PULSER_EVENTS 59 65824 UnsignedMSB4 4 Out-of-range pulser events. NEUTRON_EVENTS 60 65828 UnsignedMSB4 4 Coincidence events that meet neutron criterion. PULSER_OFFSET 61 65832 UnsignedMSB4 4 Pulser energy offset used to form PULSER_ENERGY_SUM and PULSER_ENERGY_SUM2.