Data Set Information
DATA_SET_NAME MESSENGER E/V/H MASCS 2 UVVS UNCALIBRATED DATA V1.0
DATA_SET_ID MESS-E/V/H-MASCS-2-UVVS-EDR-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview : This data set consists of the MESSENGER MASCS UVVS uncalibrated observations, also known as EDRs. The UVVS experiment is equipped with three photomultiplier tubes, which are sensitive to three different wavelength ranges. Resulting spectra cover the wavelength ranges of the far ultraviolet (FUV)(115-190 nm), middle ultraviolet (MUV) (160-320 nm), and visible (VIS) (250-600 nm), with a resolution of 0.5 nm for the FUV channel and 1.0 nm for the MUV and VIS channels. There are four standard data products: FUV data, MUV data, VIS data, and Housekeeping data. The housekeeping EDR contains instrument parameters that may be useful in analyzing the UVVS data. Instrument Overview : The MASCS instrument consists of a small Cassegrain telescope that simultaneously feeds the UVVS and VIRS experiments. MASCS UVVS experiment is a scanning grating monochromator equipped with three photomultiplier tubes, providing spectral information in the far ultraviolet (115-190 nm), middle ultraviolet (160-320 nm), and visible (250-600 nm) wavelength ranges. The UVVS detector will help determine the composition of Mercury's exosphere by measuring the spatial and vertical distribution of known species as well as search for new ones. See the INST.CAT file for more information and [MCCLINTOCK&LANK2007] for full details. Calibration Overview : This data set is NOT calibrated; it only provides the uncalibrated detector measurements. Parameters : The principal parameters when observing with the MASCS UVVS are as follows: * Start Position: The start position where the grating drive begins a scan. * Step Size: The step size in units of grating step. One grating step is equal to one arcmin. * Step Count: The number of steps the grating drive will take in a scan. The Step Count multiplied by the Step Size relates to the range of wavelengths that will be observed in one UVVS observation. * Integration Time: Integration time in grating drive loop control interrupt periods (nominally 3000 Hz). * Step Time: The step time in the grating drive loop control interrupt periods (nominally 3000 Hz). * Phase Offset: The phase offset between the beginning of the grating drive step and the start of a PMT integration in units of 0.3 milliseconds. Default value is 0 (no phase offset). By setting the phase offset to a non-zero value (reserved for contingency operations), the user will tell the software to initiate a step before the end of an integration, accounting for latencies in the motor controller. * Number of Scan Cycles: The number of times to repeat a scan. * Zigzag Option: Indicates whether grating drive moves in a 'triangle' (stepping up, then stepping down), or 'sawtooth' (stepping up, then 'flying' down) motion. A 'triangle' observation takes one grating scan stepping up the grating, then reverses direction and takes the next grating scan stepping back down the grating. A 'sawtooth' observation takes one grating scan stepping up the grating, then 'flies' the grating back to the START_POSITION to take the next observation. * Compression: Selects between 16 bit data (uncompressed) or 9 bit data (compressed). * Slit Mask Position: Indicates whether the slit mask is in the atmospheric (open) or surface (closed) position. Atmospheric slit results in a 1 deg. by 0.04 deg. instantaneous field of view (iFOV). Surface slit results in a 0.05 deg. by 0.04 deg. iFOV. * FUV On: Select if the far ultraviolet photomultiplier tube is powered on or off. * MUV On: Select if the middle ultraviolet photomultiplier tube is powered on or off. * VIS On: Select if the visible photomultiplier tube is powered on or off. Data : There are three UUVS EDR data products, one for each detector (FUV, MUV, VIS). There is also a MASCS housekeeping EDR data product generated by the MASCS instrument, which is the same for both the UVVS and VIRS components of the MASCS experiment. The EDR for one of the three detectors consists of entries for the spacecraft time and orientation, target location, values for the observing parameters set for the given observation, information about the observation, and is followed by the science scan data. The science scan data are the counts accumulated by the photomultiplier tube at a given position of the grating, in the order that the counts were collected. By using the values of the specific observing parameters that are related to the grating start position, number of grating steps, pattern of grating steps, and number of scans, each grating position can be determined and mapped to a specific wavelength. A separate EDR is created for each commanded scan set of one of the three detectors. Due to power considerations, a maximum of two photomultiplier tubes may record data at any given time; if two detectors acquire data simultaneously, two separate EDRs are still created. Data for the three UVVS detectors of the FUV, MUV, and VIS are always in separate EDRs. The MASCS Housekeeping EDR provides data about the voltage, current, and temperature readings, as well as record and software status, hardware settings, instrument status, and integration and reporting times. The MASCS Housekeeping EDR will contain all housekeeping packets generated in a given day.
DATA_SET_RELEASE_DATE 2015-03-06T00:00:00.000Z
START_TIME 2004-09-13T12:00:00.000Z
STOP_TIME N/A (ongoing)
MISSION_NAME MESSENGER
MISSION_START_DATE 2004-08-03T12:00:00.000Z
MISSION_STOP_DATE 2015-04-30T12:00:00.000Z
TARGET_NAME CALIBRATION
EARTH
MERCURY
VENUS
TARGET_TYPE CALIBRATION
PLANET
INSTRUMENT_HOST_ID MESS
INSTRUMENT_NAME MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER
INSTRUMENT_ID MASCS
INSTRUMENT_TYPE UV/VISIBLE SPECTROMETER
NODE_NAME Geosciences
ARCHIVE_STATUS ARCHIVED_ACCUMULATING
CONFIDENCE_LEVEL_NOTE Confidence Level Overview : The MASCS UVVS EDR data are the least processed data set released for the UVVS. Data presented here are an accurate representation of the UVVS data as received from the spacecraft, with minimal timing and spatial processing. Review : The UVVS EDR was reviewed internally by the MASCS team prior to release to the PDS. PDS also performed an external review of the MASCS UVVS EDRs (FUV, MUV and VIS photomultiplier tube (PMT) data each have seperate EDR types). Data Coverage and Quality : Data reported are the minimally processed data received from the spacecraft during the eighteen 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, and Mercury Orbit Year 4. 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) MASCS UVVS data were collected during all phases except Venus 1 Flyby. During these planned operational periods, the UVVS functioned nominally and the data quality was good. Additional numbered notes added as necessary. This is a high-level presentation of EDR validation. Lower level EDR (and CDR) details, including, e.g. SBOS trips, temperature alarms, and footprints on/off planet are best obtained through the Data Quality Index (DQI) of the UVVS CDR. Specific MASCS operational periods were: Start time End time Phase Name Date (DOY) Date (DOY) Operations -------------------- ----------------- ----------------- ------------- Launch 03 Aug 2004 (216) 12 Sep 2004 (256) Checkout Earth Cruise 13 Sep 2004 (257) 18 Jul 2005 (199) Starcals (1), Cover Open Earth Flyby 19 Jul 2005 (200) 16 Aug 2005 (228) Earth/Moon (2) Venus 1 Cruise 17 Aug 2005 (229) 09 Oct 2006 (282) Starcals Venus 1 Flyby 10 Oct 2006 (283) 07 Nov 2006 (311) n/a Venus 2 Cruise 08 Nov 2006 (312) 22 May 2007 (142) Starcals (3,4), Venus, Operation Tests Venus 2 Flyby 23 May 2007 (143) 20 Jun 2007 (171) Venus (5) Mercury 1 Cruise 21 Jun 2007 (172) 30 Dec 2007 (364) Starcals (6), Operation Tests Mercury 1 Flyby 31 Dec 2007 (365) 28 Jan 2008 (028) Mercury, Lyman Alpha Mercury 2 Cruise 29 Jan 2008 (029) 21 Sep 2008 (265) Starcals, Operation Tests Mercury 2 Flyby 22 Sep 2008 (266) 20 Oct 2008 (294) Mercury (7), Lyman Alpha Mercury 3 Cruise 21 Oct 2008 (295) 15 Sep 2009 (258) Starcals (8), Venus Mercury 3 Flyby 16 Sep 2009 (259) 14 Oct 2009 (287) Mercury (9), Lyman Alpha Mercury 4 Cruise 15 Oct 2009 (288) 03 Mar 2011 (062) Starcals, Venus (10), Operation Tests Mercury Orbit 04 Mar 2011 (063) 17 Mar 2012 (077) Mercury (11-12), Starcals, Venus Mercury Orbit Year 2 18 Mar 2012 (078) 17 Mar 2013 (076) Mercury (13), Starcals Mercury Orbit Year 3 18 Mar 2013 (077) 17 Mar 2014 (076) Mercury (14), Starcals Mercury Orbit Year 4 18 Mar 2014 (077) 17 Mar 2015 (076) Mercury, Comet Encke, Comet ISON, Starcals Notes: (1) Starcals before June 2005 viewed through cover window. (2) UVVS command errors in corona scans reduced number of scans executed by ~1/2. SBOS trips at moon stopped UVVS VIS-PMT data as expected. 10 Missing MUV packets at this time. (3) One starcal missed target due to star tracker error. (4) Test and switch over to macro-based commanding of UVVS. (5) SBOS trips at Venus stopped green line scan. (6) S/C event during starcal; instrument turned off during Starcal. (7) UVVS grating offset affects data during first Mercury flyby. The only effect in the EDRs is that the range of wavelengths actually measured is different from the nominal range and spectra will be shifted to longer wavelengths. The offset was 4 grating steps. (8) Pointing error during May 2009 starcal; star not observed. (9) Flyby anomaly - no data after Mercury Closest Approach until post-flyby Mercury-as-star observations. (10) Missing packet in Dec 2010 turn-on sequence. Missing packets (5 second observations) noted in some H Lyman alpha scans, possibly simply timing cutoffs, no data quality compromise. (11) Elevated hot season temperatures. (12) Lost data Events during Orbit: 11123 FPP 'High Temperature' warning, Instrument off for 2 days, setting set too low. FPP temps reset to higher value. (13) Occasional single event upsets, usually related to solar activity, usually affecting the VIRS component of MASCS, resulted in unscheduled power cycling of MASCS. (14) UVVS grating offset affects data from September 5 through November 22, 2013. See note #7 for description of effects on data. The offset was 6 grating steps. Cruise operations/observations have additional details in the Master Cruise Operations Table (a Microsoft Excel file) in the Extras directory. There are slightly fewer UVVS Science CDRs because there were a few EDRs that contained no data at all, just header information (i.e. loop was begun, but halted by normal macro operations before data were taken.) Limitations : This data set is minimally processed data. The data are received from the spacecraft telemetry and ingested into the MESSENGER Science Operations Center (SOC). No data gaps other than understood UVVS command loop errors and SBOS trips have been identified for any of the MASCS operational periods.
CITATION_DESCRIPTION Izenberg, N., MESSENGER E/V/H MASCS 2 UVVS UNCALIBRATED DATA V1.0, MESS-E/V/H-MASCS-2-UVVS-EDR-V1.0, NASA Planetary Data System, 2007.
ABSTRACT_TEXT Abstract : This data set consists of the MESSENGER MASCS UVVS uncalibrated observations, also known as EDRs. The MASCS UVVS experiment is a scanning grating monochromator equipped with three photomultiplier tubes. There are three UUVS EDR data products, one for each detector, which cover the wavelength ranges of the far ultraviolet (FUV), middle ultraviolet (MUV), and visible (VIS).
PRODUCER_FULL_NAME NOAM IZENBERG
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