Data Set Overview : This data set consists of the MESSENGER GRS calibrated observations, also known as CDRs, and the GRS reduced data known as RDRs. There are seven standard CDR data products associated with the GRS sensor. A single CDR data file contains the observations with a time tag corresponding to a given Earth day. There are seven CDR data product files: one engineering file, one count rate file, and five spectra files. The engineering files contain selected relevant data from the EDR status files, converted to calibrated physical units. The shield count rate files contain summed total event rates in the anti-coincidence shield at 10-ms integration cadence. In addition to the spectra, the spectra files contain spacecraft navigation and attitude data derived from SPICE files, that are relevant to the GRS, as well as selected engineering data relevant to the GRS. The raw spectrum files contain Ge raw spectra and counter data, the anticoincidence spectrum files contain Ge anticoincidence spectra and counter data, and the shield spectrum files (3 versions) contain shield spectra and counter data. There is one RDR product which contains the spectral sum over a one year period. These sums are created from the anti-coincidence and raw spectra.   Instrument Overview : The GRS detector is a high-resolution coaxial germanium crystal 50 mm in diameter and 50 mm in length, chosen for its radiation damage resistance and annealing capabilities. The detector is rigidly clamped in a hermetically sealed Al capsule pressurized with clean, dry nitrogen. The capsule is cooled to an operating temperature in the 80-95 K range by a mechanical cryocooler. A plastic scintillator anti-coincidence shield surrounds the germanium detector in its sides and back, for rejection of cosmic-ray background. Galactic cosmic rays continuously bombard the surface of Mercury, and through interactions with the surface, gamma-rays of discrete energies that are characteristic of specific elements are created. A fraction of these gamma-rays, as well as those from the decay of radiogenic elements escape from the surface, where they can be detected by the orbiting GRS. Gamma-ray fluxes are measurable at altitudes up to 1000 km and for gamma-rays up to about 10 MeV that emanate from depths of up to tens of centimeter beneath the surface. Detected fluxes are generally low and require numerous orbital passes over a specific region to obtain a statistically well-defined energy spectrum. The measurements of elements such as Fe, Si, Mg, Ca, Ti, K and Th by GRS will provide insight into distinguishing between different formation models for Mercury as well as other planetary evolution issues.  See the INSTRUMENT.CAT file for more information and [GOLDSTENETAL2007] for full details.   Calibration Overview : This data set is calibrated; it provides the calibrated GRS sensor measurements. Raw engineering units have been converted to calibrated physical units. Where the unit value depends on temperature, temperature corrections based on flight and ground data were performed. The Ge raw and anticoincidence spectra have a temperature dependence through the gain change in the preamplifier and shaper amplifier, which have been corrected with flight data. The Ge spectra have been normalized to 0.604 keV/channel, based on strong gamma peaks in the temperature-corrected spectra, providing the transformation from counts per channel to counts per energy bin. Spectra derived from the anticoincidence detector are not calibrated in energy but remain as channel. Spacecraft navigation, attitude, and time data relevant to the GRS have been added to each spectral file based on calibrated SPICE data. There was no consideration of deadtime, detector efficiencies, or gamma-ray attenuation and no spatial processing.   Parameters : The principal parameters when observing with the GRS are as follows:  * Accumulation Time: The accumulation time, in seconds, of the Ge detector.   Data : There are seven standard CDR data products associated with the GRS sensor: the Ge raw spectra data GRS_CAL_RAW, the Ge anti-coincidence spectra data GRS_CAL_AC, the shield spectra data GRS_CAL_SH, GRS_CAL_SH2, and GRS_CAL_SH3, the shield count rate data GRS_CAL_SCR and the engineering data GRS_ENG. A single CDR data file contains the observations with a time tag corresponding to a given Earth day. There is one RDR product GRS_RDR_SUM associated with the GRS sensor: the sum of one Earth year of Ge raw spectra data and Ge anti-coincidence spectra data.  The Ge raw spectra data file contains a set of raw spectra data collected from the high-purity Ge detector during a specified amount of time. These data are contained in 16,384 (2^14) channels, which can be used to create a histogram that shows the distribution of events (number of counts) as a function of energy (channel number). Because of the low count rates usually encountered, accumulation times of minutes to hours are normal. Temperature correction of the spectra shifts event energies with respect to channel energy bands, requiring rebinning of the counts fractionally among neighboring channels, so spectra counts are represented as floating point numbers. Spectrum Counters are also included, as are spacecraft navigation and attitude parameters relevant to the GRS and UTC time, obtained from calibrated SPICE data at the midpoint of the time interval. Selected engineering data relevant to the GRS, in calibrated physical units and temperature corrected as necessary, are also included, interpolated to the midpoint of the time interval.  The Ge anti-coincidence spectra data file contains a set of spectra data collected from the high-purity Ge detector during a specified amount of time, for events not in coincidence with events detected in the shield. These data are contained in 16,384 (2^14) channels, which can be used to create a histogram that shows the distribution of events (number of counts) as a function of energy channel number). Because of the low count rates usually encountered, accumulation times of minutes to hours are normal. Temperature correction of the spectra shifts event energies with respect to channel energy bands, requiring rebinning of the counts fractionally among neighboring channels, so spectra counts are represented as floating point numbers. Spectrum Counters are also included, as are spacecraft navigation and attitude parameters relevant to the GRS and UTC time, obtained from calibrated SPICE data at the midpoint of the time interval. Selected engineering data relevant to he GRS, in calibrated physical units and temperature corrected as necessary, are also included, interpolated to the midpoint of the time interval.  The GRS shield spectra data file contains a set of spectra data collected from the borated-plastic shield during a specified amount of time. These data are contained in 1024 (2^10) channels, which can be used to create a histogram that shows the distribution of events (number of counts) as a function of energy (channel number). Because of the low count rates usually encountered, accumulation times of minutes to hours are normal. Spectrum Counters are also included, as are spacecraft navigation and attitude parameters relevant to the GRS and UTC time, obtained from calibrated SPICE data at the midpoint of the time interval. Selected engineering data relevant to the GRS, in calibrated physical units and temperature corrected as necessary, are also included, interpolated to the midpoint of the time interval.  The GRS shield count rate data file contains are time series measurements of the total count rate measured by the GRS anti-coincidence shield, and are due to incident particles (primarily electrons, but also gamma-rays, protons, and neutrons). Each data product, which is associated with a given measurement time, is subdivided into 10-ms-cadence measurements of the count rate, which are sequentially assigned to the 16,384 channels in the spectrum array. For short integration periods, this array is not filled and remaining channels are assigned values of zero. For longer integration times, the array is filled prior to the end of the data collection period and the final channel includes the sum of all values collected after the array is filled. This typically occurs when the spacecraft is far from Mercury, and therefore the measurements of less interest. Zeros at the beginning of the array correspond to an approximately 0.5-sec-long electronics deadtime at the beginning of each run. This data product was created following the February 25, 2013 flight software upload. After a commissioning phase, official production of the new data products commenced on March 18, 2013.  The GRS engineering data file contains a set of selected engineering data from the GRS EDR status data relevant to the GRS, in calibrated engineering units, temperature corrected as necessary, at specified times. Included are such parameters as high voltages, electronics voltages and currents, preamplifier and shaping amplifier temperatures, Ge temperature, and cryocooler currents and temperature. Noise spikes in the data have been filtered out.  The GRS summed spectra data file contains a set of spectral sums and ancillary information connected with the sums. There are four sums in each record: a sum of the Ge raw spectra data, Ge raw spectra corrected data, Ge anti-coincidence spectra data, and Ge anti-coincidence corrected spectra data. There are also minimum, maximum, mean and standard deviation for several temperature readings as well as altitude and latitude and longitude variations.  The user is referred to the GRS CDR-RDR-DAP SIS in the DOCUMENT directory for details as to what types of sums are created and what the altitude and spatial representation are.

Confidence Level Overview : The GRS CDR/RDR data form the calibrated data set released for the GRS. Data presented here are as accurate a representation of the GRS calibrated data as possible at time of delivery. There may be further recalibrated deliveries of this data if needed and future data may require calibration changes.   Review : The GRS CDR/RDR SIS and data were reviewed internally by the GRS team prior to release to the PDS. PDS also performed an external review of the GRS CDR/RDR. The CDR/RDR data are based on the uncalibrated EDR data and the calibrated data, which have been previously reviewed, and GRS science spectra have been analyzed based on the EDR data. However, GRS science analysis based on this CDR/RDR data has not yet taken place; when this occurs, it may be found that a new release of these CDR/RDR data, possibly recalibrated, is needed.   Data Coverage and Quality : Data reported are the calibrated data received from the spacecraft during the the following mission phases: Launch, Earth Cruise, Earth Flyby, Venus 1 Cruise, Venus 1 Flyby, Venus 2 Cruise, Venus 2 Flyby, Mercury 1 Cruise, Mercury 1 Flyby, Mercury 2 Cruise, Mercury 2 Flyby, Mercury 3 Cruise, Mercury 3 Flyby, Mercury 4 Cruise, Mercury Orbit, Mercury Orbit Year 2, Mercury Orbit Year 3, Mercury Orbit Year 4, and Mercury Orbit Year 5. These mission phases are defined as:  Start time End time Phase Name Date (DOY) Date (DOY) ------------------- ----------------- ----------------- Launch 03 Aug 2004 (216) 12 Sep 2004 (256) Earth Cruise 13 Sep 2004 (257) 18 Jul 2005 (199) Earth Flyby 19 Jul 2005 (200) 16 Aug 2005 (228) Venus 1 Cruise 17 Aug 2005 (229) 09 Oct 2006 (282) Venus 1 Flyby 10 Oct 2006 (283) 07 Nov 2006 (311) Venus 2 Cruise 08 Nov 2006 (312) 22 May 2007 (142) Venus 2 Flyby 23 May 2007 (143) 20 Jun 2007 (171) Mercury 1 Cruise 21 Jun 2007 (172) 30 Dec 2007 (364) Mercury 1 Flyby 31 Dec 2007 (365) 28 Jan 2008 (028) Mercury 2 Cruise 29 Jan 2008 (029) 21 Sep 2008 (265) Mercury 2 Flyby 22 Sep 2008 (266) 20 Oct 2008 (294) Mercury 3 Cruise 21 Oct 2008 (295) 15 Sep 2009 (258) Mercury 3 Flyby 16 Sep 2009 (259) 14 Oct 2009 (287) Mercury 4 Cruise 15 Oct 2009 (288) 03 Mar 2011 (062) Mercury Orbit 04 Mar 2011 (063) 17 Mar 2012 (077) Mercury Orbit Year 2 18 Mar 2012 (078) 17 Mar 2013 (076) Mercury Orbit Year 3 18 Mar 2013 (077) 17 Mar 2014 (076) Mercury Orbit Year 4 18 Mar 2014 (077) 17 Mar 2015 (076) Mercury Orbit Year 5 18 Mar 2015 (077) 30 Apr 2015 (120)  These specific operational periods in relation to the mission phases were:  Start time End time Phase Name Date (DOY) Date (DOY) Sensor -------------------- ----------------- ----------------- ------ Launch 12 Aug 2004 (225) 13 Aug 2004 (226) Earth Cruise 10 Nov 2004 (315) 16 Nov 2004 (321) Ge Earth Flyby No Data Venus 1 Cruise No Data Venus 1 Flyby No Data Venus 2 Cruise 27 Mar 2007 (088) 30 Mar 2007 (089) shield Venus 2 Flyby 04 Jun 2007 (155) 08 Jun 2007 (159) shield Mercury 1 Cruise 26 Sep 2007 (269) 29 Sep 2007 (272) shield Mercury 1 Flyby 05 Jan 2008 (005) 15 Jan 2008 (015) shield Mercury 1 Flyby 13 Jan 2008 (013) 15 Jan 2008 (015) Ge Mercury 2 Cruise No Data Mercury 2 Flyby 03 Oct 2008 (277) 06 Oct 2008 (280) shield Mercury 2 Flyby 04 Oct 2008 (278) 06 Oct 2008 (280) Ge Mercury 3 Cruise 24 Sep 2009 (267) 27 Sep 2009 (270) shield Mercury 3 Flyby 28 Sep 2009 (271) 06 Oct 2009 (279) Ge Mercury 4 Cruise 02 Apr 2010 (092) 12 Apr 2010 (102) shield Mercury 4 Cruise 13 Apr 2010 (103) 15 Apr 2010 (105) Ge Mercury 4 Cruise 17 Sep 2010 (260) 24 Sep 2010 (267) shield Mercury Orbit 23 Mar 2011 (082) 03 Jun 2011 (154) Ge Mercury Orbit 11 Jun 2011 (162) 14 Jun 2011 (165) Ge Mercury Orbit 16 Jun 2011 (167) 05 Jul 2011 (186) Ge Mercury Orbit 20 Jul 2011 (201) 25 Jul 2011 (206) Ge Mercury Orbit 28 Jul 2011 (209) 06 Sep 2011 (249) Ge Mercury Orbit 08 Sep 2011 (251) 17 Sep 2011 (260) Ge Mercury Orbit Year 2 18 Mar 2012 (078) 15 Jun 2012 (167) shield Mercury Orbit Year 3 18 Mar 2013 (077) 17 Mar 2014 (076) shield Mercury Orbit Year 4 18 Mar 2014 (077) 17 Mar 2015 (076) shield Mercury Orbit Year 5 18 Mar 2015 (077) 30 Apr 2015 (120) shield  In this list, 'shield' means shield only and 'Ge' means Ge and shield. The GRS operational mode during most of the flyby time periods was a 'sleep mode' during which an operational heater maintained the cryocooler temperature at a constant value (to avoid temperature cycling of the cryocooler He seals) and the remainder of the instrument was shut down. Status data are continuously collected in this mode. Cryocooler exercises were conducted approximately every 6 months, but this is of engineering interest only.  Data from the cryocooled GRS high-resolution Ge detector were collected only during the full functional test in November 2004 and during the Mercury flybys in January and October 2008 and September-October 2009. This limitation preserves the lifetime of the limited-life cryocooler.  Data from the borated plastic shield were collected as part of a periodic cryocooler exercise; for the Venus-2 flyby (as another neutron detector to aid the NS); during the Mercury 1 Cruise in September 2007; for the Mercury 1, 2, and 3 Flybys.  A nonscience 'aliveness' test was conducted in August 2004.  The Ge detector energy resolution was somewhat degraded during Mercury Flyby 1 due to crystal displacement damage by cosmic rays, despite a 3-day anneal at 84C prior to the Flyby. To improve energy resolution for Flyby 2, the detector was kept at room temperature in July through mid-September in 'hot zombie' mode (no communication with the DPU to reduce memory usage and avoid upset events from cosmic rays). Then a 14-day anneal at 84C was conducted. After this, energy resolution was improved to nearly that found in the first cruise test shortly after launch.  During Mercury Flyby 3, the GRS data were collected only up to approximately 6 minutes before closest approach, at approximately 661 km altitude, due to a S/C safing that occurred. The GRS was restarted once the S/C was promoted to operation, but the S/C was far from the planet by this time. It is estimated that only approximately 18 percent of the signal counts from the planet were obtained below 2500 km altitude, compared to previous flybys. After the Ge detector recooled to operational temperature, engineering tests were run involving Ge temperature and high-voltage changes.  The shield was operated during May 2009 for some engineering tests. Otherwise the GRS operational mode during the Mercury 3 Cruise was 'warm zombie' mode, which performs a relatively low temperature Ge anneal to reduce radiation damage. Also the operational heater maintains the cryocooler temperature, to avoid cycling of the cryocooler He seals. On September 2 2009, the GRS was brought out of warm zombie mode and a 3-day Ge anneal at 84C was then performed. After this anneal the Ge energy resolution appeared to be close to that obtained for Mercury Flyby 2.  During Mercury 4 Cruise, the GRS remained in warm zombie mode, except the shield was on for some spectral tests on shield-only data and the Ge detector and shield were on for some spectra tests on coincidence spectra between the shield and and the Ge detector.  Just before orbit insertion, the GRS was brought out of warm zombie mode, and the Ge crystal was annealed for 7 days at 84C. After a few days of orbital operations the Ge energy resolution was measured to be close to the same value obtained for the M3 flyby. S/C temperatures were somewhat higher than expected during orbital operations, but the GRS cryocooler was able to cool the Ge detector easily.  During orbital operation, the GRS remained on continuously, except for periods when the high voltage was down, for various reasons, including an X-class SPE (Solar Particle Event) that safed the detector, OCMs (Orbital Correction Maneuvers), and cryocooler temperature setpoint changes. Periods having conditions that lead to broad energy resolution, such as radiation damage revealed by a Ge temperature increase or large very low-energy noise, have also been removed. Not shown in the table of operational periods are periods of SPEs that did not safe the detector: SPE2 08-02-2011, SPE3 08-04/05-2011, SPE4 08-09-2011, and SPE5 09-08/09-2011. These time periods should probably be eliminated from analysis, due to count-rate saturation and strong activation of gamma-ray peaks.  Beginning on 11 October, 2011, the HPGe detector began registering anomalous counts in the low-energy (< 300 keV) portion of the spectrum. While these events are lower in energy than the gamma-ray photopeaks of interest, the resulting count rate during these periods is sufficiently high to degrade the energy resolution for the detection of all gamma rays, regardless of energy. The magnitude of the anomalous counts and corresponding degradation of the energy resolution varies, and all data acquired after 11 October, 2011 should be carefully evaluated for its energy resolution prior to analysis. Particular care should be taken prior to summing individual gamma-ray spectra with differing energy resolution to produce summed spectra for analysis.  The GRS operated in anomalous count rate mode for the remainder of its life. The high voltage (HV) was maintained at its nominal value of 3200 V until 18 November, 2011, when it was lowered to 2700 V. It returned to 3200 V on 21 November, 2011, which was followed by a change to 2400 V. These changes were implemented in an attempt to maintain the highest possible energy resolution in the presence of the increased leakage current.  A short detector annealing activity took place from 15 December, 2011 to 21 December, 2011. This was followed by the arrival of an energetic solar particle event on 26 December, 2011 to 27 December, 2011.  A detector annealing activity took place from 19 March, 2012 to 29 March, 2012. Following this activity the detector leakage current was observed to have increased significantly with a corresponding degradation in the leakage current.  From 30 March, 2012 to 11 April, 2012, the detector high voltage value was varied between 1500 to 2400 V to characterize the energy resolution of the system as a function of high voltage.  A detector annealing activity took place from 11 April, 2012 to 28 April, 2012. Following this activity, the detector was operated at 2400 V.  In an attempt to preserve the limited lifetime of the GRS cryocooler, the detector was kept warm from 5 May 2012 to 1 June 2012. This time period corresponded to a time of elevated spacecraft temperatures. On 8 June, 2012 a week long detector annealing activity began.  On 15 June, 2012, the GRS cryocooler failed after approximately 9,500 hours of operation. This compares favorably to the 8,000 hour mean lifetime for these coolers. The failure occurred during a routine detector cool down following the 8 June 2012 annealing activity. Several unsuccessful attempts to revive the cooler have been made. Without the ability to maintain the HPGe detector at cryogenic temperature, gamma-ray measurements are not possible. No Germanium data collected after June 15, 2012 will be supplied to PDS for archiving.  On 25 February, 2013, new flight software was uploaded to the GRS. The purpose was to optimize the capability of the instrument to characterize neutron emission from Mercury's surface by changing the gain of the shield spectrum. Additionally, a new data product was added (SCR), which produces 10-ms cadence measurements of the total shield count rate. Because the shield responds to charged particles, these measurements represent the highest time cadence samples of the energetic charged particle environment around Mercury. The first several weeks were devoted to parameter optimization, with official data collection beginning on 18 March, 2013. Following the software upload, CDR creation was handled by APL instead of the University of Arizona, and the format of the shield products changed (SH3). See the CDR-RDR-DAP SIS in the DOCUMENT directory for details.  Beginning on 9 September, 2014, a new data operations mode was implemented in which the SHI data is acquired at a higher time cadence when MESSENGER is within 500 km altitude of Mercury. During these periods, SCR data collection is temporarily suspended. his operational cadence lasted until the end of the mission.  In order to reduce the load on the spacecraft solid state recorder, GRS FPGA data collection was suspended on DOY 2015 092 through the end of the mission. In addition, the GRS Software Counters (SWC) were collected at a reduced cadence from DOY 2015 069 until the end of the mission. This necessitated a need to interpolate SWC-derived housekeeping values in the EDRs from this date. This includes the 'DEADTIME_FRAC' and 'SHIELD_CHG_RSET' values in SH3 and SCR.  Periods of elevated count rates resulting from spacecraft-incident SPE events includes data collected on:  3-11 June, 2011; 2 August, 2011; 4-5 August, 2011; 9 August, 2011; 6 September, 2011; 7 September, 2011; 8 September, 2011; 22-23 September, 2011; 4-6 October, 2011; 14 October, 2011; 17 October, 2011; 3-5 November, 2011; 8-10 November, 2011; 17-18 November, 2011; 19-21 November, 2011; 23 January - 3 Feburary, 2012; 3 March, 2012;  Post-January 2012 flares are difficult to isolate in the count-rate anomaly compromised dataset. Care should be used when utilizing these data as they may also contain gamma-ray detections resulting from prompt and/or long-lived activation products. The count rate anomaly issue does not apply to data collected following the 25 February, 2013 flight software upload.  For measurements taken following the 25 February, 2013 software upload, the following times included data compromised by SPEs:  15-16 March, 2013; 11-12 April, 2013; 21-22 April, 2013; 13-14 May, 2013; 31 May - 1 June, 2013; 21-24 June, 2013; 19 August - 9 September, 2013; 30 September - 2 October, 2013; 5-7 October, 2013; 11-15 October, 2013; 22-23 October, 2013; 25-30 October, 2013; 4-10 November, 2013; 19-21 November, 2013; 29 November - 1 December, 2013; 13-16 December, 2013; 25-28 December, 2013; 6-13 January, 2014; 22-23 January, 2014; 27-31 January, 2014; 10-15 February, 2014; 17-21 February, 2014; 24 February - 8 March, 2014; 12-14 March, 2014; 24-25 April, 2014; 5-6 May, 2014; 4-6 June, 2014; 11 June, 2014; 12-13 June, 2014; 17 June, 2014; 8-9 August, 2014; 1 September - 1 October, 2014; 14-19 October, 2014; 20-22 October, 2014; 26 October, 2014; 27 October, 2014; 29-30 October, 2014; 1 November; 3-6 November, 2014; 13-15 December, 2014; 13-23 December, 2014; 26-27 December, 2014; 21 January, 2015; 21-23 February, 2015; 2-4 March, 2015; 24 March - 3 April, 2015; 4-5 April, 2015; 13-16 April, 2015; 28-29 April, 2015;  These time periods are denoted more precisely within the archive via the 'BAD_DATA_FLAG'. The degree to which science data can be derived from these SPE-comprised periods varies on an event-by-event basis.  Periods with no science data, corresponding to instrument safing or operations activities include:  4 June, 2011; (Safed) 15 June, 2011; (HV shutdown during OCM) 6 July, 2011; (HV off) 12-20 July, 2011; (GRS Annealing) 26 July, 2011; (HV shutdown during OCM) 7 September, 2011; (HV shutdown during OCM) 24 October, 2011; (HV shutdown during OCM) 8 November, 2011; (HV off) 4-6 December, 2011; (Instrument Safing) 15-20 December, 2011; (Detector Annealing) 2-12 March, 2012; (HV shutdown during OCM) 24-25 April, 2013; (HV shutdown during OCM) 21-24 June, 2013; (Instrument Safing due to SPE) 19-22 August, 2013; (Instrument Safing due to SPE) 25-30 October, 2013; (Instrument Safing due to SPE) 25-28 December, 2013; (Instrument Safing due to SPE) 17 June, 2014; (HV shutdown during OCM) 1-3 September, 2014; (Instrument Safing due to SPE) 10-12 September, 2014; (Instrument Safing due to SPE) 10-11 September, 2014; (Instrument Safing due to SPE) 12 September, 2014; (HV shutdown during OCM) 24 October, 2014; (HV shutdown during OCM) 13-15 December, 2014; (Instrument safing due to SPE) 20 December, 2014; (HV shutdown during OCM) 21-22 December, 2014; (HV shutdown during OCM) 21 January, 2015; (HV shutdown during OCM) 24-25 March, 2015; (Instrument saying during SPE) 27 March, 2015; (HV shutdown during OCM)  These time periods are denoted more precisely within the archive via the 'BAD_DATA_FLAG'.  The HPGe high voltage (HV) was changed periodically from December 2011 until 15 June 2012 to improve performance during periods of anomalously high count rates thought to be due to increased leakage current following the December 2011 annealing. The data are tagged via the 'BAD_DATA_FLAG', and its usefulness varies and should be evaluated carefully by the end user.  Restrictions on data generation resulting from limited space on the spacecraft data record resulted in SCR products being suspended during the following periods:  14 December 2013 - 2 January, 2014; 16 January 2014 - 1 February, 2014;  The latter portions of data collected on 8 and 10 April, 2015 are missing from the CDRs.  Finally, the MESSENGER spacecraft solid state recorder filled and stopped recording new data during DOY 2014 360, resulting in a permanent ~3-hour-long data gap from approximately 14:15 to 17:38.  Limitations : Though calibrated, this data set is based on minimally processed data received from the spacecraft telemetry and ingested into the MESSENGER Science Operations Center (SOC). No corrupted data have been identified for any of the GRS operational periods. A single data gap exists and was denoted in this document. Although there may be some data not identified as missing or corrupted, such data should be minimal and a very small fraction of the available data.