Data Set Information
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| DATA_SET_NAME |
MESSENGER E/V/H MASCS 4 UVVS DERIVED DATA V1.0
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| DATA_SET_ID |
MESS-E/V/H-MASCS-4-UVVS-DDR-V1.0
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| NSSDC_DATA_SET_ID |
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| DATA_SET_TERSE_DESCRIPTION |
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| DATA_SET_DESCRIPTION |
Data Set Overview : This data set consists of the MESSENGER MASCS UVVS derived data records (DDRs). 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, 0.7 nm for the MUV channel, and 0.6 nm for the VIS channel. There is a data overlap with VIRS in the VIS wavelength range. DDR products are generated from CDRs of orbital data. There are three types of UVVS DDRs: surface, atmosphere, and atmospheric model. MUV Surface DDRs: For the UVVS MUV surface DDR data products, one DDR contains all the derived reflectance data from one MUV surface observation. Only targeted surface observations acquired during Mercury orbit were processed to a DDR (i.e., flyby measurements are excluded). Thus, there are only 4596 total UVVS DDRs. The first step is to bin the CDR spectral radiance (L) to 2 nm intervals in the wavelength range 210-300 nm. Next, this is divided by the expected spectral irradiance, equivalently binned, from a Lambertian surface normally illuminated by the Sun. We use the measured solar irradiance from the SORCE-SOLSTICE instrument [McClintock et al, 2005], averaged over its first year of operation (starting in May 2003), and scaled in magnitude to the Mercury orbital distance at the time of each observation. The derived radiance is known as the 'radiance factor' or 'I/F', and is contained in the field IOF_BIN_DATA. An estimate of the uncertainty is contained in the field IOF_BIN_NOISE_DATA. A photometric normalization procedure, described in Izenberg et al (2014), is used to convert the spectral reflectance to a common photometric geometry (i:45 deg., e:45 deg., a:90 deg.); this is contained in the field PHOTOM_IOF_BIN_DATA and the associated uncertainty in PHOTOM_IOF_BIN_NOISE_DATA. There are two types of MUV surface observations, with macro identifiers 48 and 49; both use a grating step of 1 and the surface slit position, and both have a minimum wavelength of 172.20 nm. They differ by the total number of steps and thus the maximum wavelength, with macro 48 at 378.34 nm and macro 49 at 320.62 nm. Because the MUV surface DDRs are restricted to the wavelength range 210-310 nm, these two types of observations result in equivalent data products. One observation set is associated with two surface DDR data products: a science header table, containing the instrument command parameters for a given observation, and a science data table, containing counts, derived science data, and pointing information for each wavelength bin (~5 grating steps) of an observation. The surface DDRs are in binary table format, and the science header and data tables are each described by a detached PDS label. The label points to an associated format file that defines the fields of the binary table contained within the data file. Izenberg, N.R., Klima, R.L., Murchie, S.L., Blewett, D.T., Holsclaw, G.M., McClintock, W.E., Malaret, E., Mauceri, C., Vilas, F., Sprague, A.L., Helbert, J., Domingue, D.L., Head, J.W., Goudge, T.A., Solomon, S.C., Hibbitts, C.A., Dyar, M.D., 2014. The low-iron, reduced surface of Mercury as seen in spectral reflectance by MESSENGER. Icarus 228, 364-374. doi:10.1016/j.icarus.2013.10.023. McClintock, W.E., Rottman, G.J., Woods, T.N., 2005. Solar-Stellar Irradiance Comparison Experiment II (SOLSTICE II): Instrument Concept and Design, in: Rottman, G., Woods, T., George, V. (Eds.), The Solar Radiation and Climate Experiment (SORCE). Springer New York, pp. 225-258. FUV Surface DDRs: FUV surface DDRs are structured similarly to MUV DDRs. There are only a few solar atomic emissions that are bright enough to be observed in the FUV channel; therefore, we restrict FUV DDRs to surface observations that have used macro 63, typically used for atmospheric scans of hydrogen Lyman alpha (121.6 nm) and oxygen (130.4 nm). For any single observation, there are two distinct scan ranges: a 31-step scan from 119.1 nm to 122.45 nm and a 21-step scan from 129.24 nm to 131.46 nm. Each of these two ranges consists of contiguous grating positions in 1-step increments. A notable difference from the MUV DDRs is that these FUV observations use the long, atmospheric slit position in order to obtain sufficient signal. The measured radiance and the solar irradiance are integrated in the spectral ranges 121.5 +/- 0.5 nm and 130.5 +/- 0.5 nm. The reflectance (I/F) is otherwise calculated identically as that for the MUV DDRs, resulting in values at only these two wavelengths. The Sun is much more variable at FUV wavelengths than in the MUV [Rottman, 1999]. We use the daily-averaged solar spectral irradiance provided by SORCE-SOLSTICE [McClintock et al, 2005] and available from the LISIRD database (http://lasp.colorado.edu/lisird/). The SORCE spacecraft operates in a low-Earth orbit (LEO) and, in general, views a different hemisphere of the Sun than that which contributes to the solar irradiance experienced at Mercury. A temporal/spatial interpolation is required that produces an estimated solar spectral irradiance at any arbitrary time and position of Mercury. There are a few periods of time when SOLSTICE was not operating nominally and did not produce data products. In these cases, we used the Flare Irradiance Spectral Model (FISM), also available on LISIRD. In order to match the measurements of SOLSTICE, we smooth both datasets with a 60-day filter using the LOWESS algorithm. The FISM time-series of the 1-nm binned 121.5 nm and 130.5 nm flux was normalized to the low-frequency response measured by SOLSTICE. Next, the contrast of the corrected FISM time-series was adjusted to match that of SOLSTICE; it was determined that a factor of 0.7 was required to minimize the error. A composite time-series was then constructed with the SOLSTICE measurements and the corrected FISM fluxes to fill the gaps. Compared to the MUV DDR surface data products, a new field (BIN_SOLAR_IRRADIANCE_W) was created to contain the solar irradiance used to calculate the reflectance. McClintock, W.E., Rottman, G.J., Woods, T.N., 2005. Solar-Stellar Irradiance Comparison Experiment II (SOLSTICE II): Instrument Concept and Design, in: Rottman, G., Woods, T., George, V. (Eds.), The Solar Radiation and Climate Experiment (SORCE). Springer New York, pp. 225-258. Rottman, G., 1999. Solar ultraviolet irradiance and its temporal variation. Journal of Atmospheric and Solar-Terrestrial Physics 61, 37-44. doi:10.1016/S1364-6826(98)00114-X. Atmosphere DDRs: The UVVS Atmosphere Derived Data Records consist of time-ordered sequences of radiance values that are measured along lines of sight perpendicular to Mercury radius vectors. The viewing direction for each measurement is provided by the latitude, longitude, and altitude of the spacecraft and the latitude, longitude, and altitude of the minimum ray (See Figure 5a in UVVS_CDR_DDR_SIS.PDF, located in the DOCUMENT directory of this volume). There are three general geometry-based classifications of Atmosphere DDRs and a series of orbit-level summary Atmosphere DDRs. The first geometry-based classification is the dayside limb scans (LS), which are acquired as sets of limb altitude profiles at specific local times. These are all of the observation type UVVSDaysideScan (see UVVS_CDR_DDR_SIS.PDF for a description of the various UVVS observation types). The second geometry-based classification is the dayside and nightside limb drift profiles (LD), which are acquired in a more random fashion. These drift observations were serendipitous exospheric limb profile measurements during ride-alongs with other instruments, and they can be composed of data from several of the defined observation types. They occurred anywhere in the orbit as long as the UVVS line of sight observed off the planetary limb. As ride-along observations, the pointing was dictated by the other instruments; thus, the UVVS pointing may have varied during any given drift observation, and the altitudes covered ranged from as few as a hundred kilometers to as many as several thousand kilometers. They are an attempt to provide as many altitude profiles as possible in addition to the defined limb scans in the first DDR classification. The basic geometry of these is illustrated in Figure 2c of UVVS_CDR_DDR_SIS.PDF. The final geometry-based classification is the nightside tail sweeps (NS), which are simply the UVVSExoScans that occurred on the nightside of the planet. Each of these three geometry-classified Atmosphere DDR products is generated for the three major exosphere species that were regularly observed by the UVVS: sodium (Na), magnesium (Mg), and calcium (Ca). The Mg data in the DDRs are observations of the emission line at 285.3 nm, the Ca data are observations of the emission line at 422.8 nm, and the Na data are observations of the doublet emission lines at 589.2 nm (D2) and 589.8 nm (D1). All wavelengths are specified in vacuum. The total radiance calculated for Na pertains to the sum of the D1 and D2 lines, which overlap to some extent at the spectral resolution of the UVVS. A single file for the geometry-classified Atmosphere DDRs contains all of the observations for a given species and geometry classification that were acquired during a single Mercury year. 'Mercury year' is defined as the time to cover the full 360 degrees of Mercury's orbit around the Sun, with the starting point being at 0 degrees true anomaly. Because MESSENGER orbit insertion and the start of science data acquisition occurred at 73 degrees true anomaly, the first Mercury year only covered a range from 73 degrees to 360 degrees. The final Mercury year was also a partial year, covering true anomalies from 0 to 64 degrees at mission end. The final Atmosphere DDR type is the orbit-level summary file. As opposed to the geometry-based classification Atmosphere DDRs described above, which group observations of a particular geometry together by Mercury year and species, these orbit-level summary Atmosphere DDRs gather together all of the observations for a given species for a given orbit into a single Atmosphere DDR file. There are thus a series of Atmosphere DDR files for every orbit during which science data for a given species were acquired. All observation types are included in these files, but as with the geometry-classified Atmosphere DDRs, some data are excluded (e.g., saturated spectra, spectra with the slit half on/half off the planet). There are versions of these orbit-level summary files for Na, Ca, and Mg. These orbit-level summary Atmosphere DDRs represent the most complete set of usable exospheric data on Na, Ca, and Mg. The geometry-classified Atmosphere DDRs are simply subsets of the data in these orbit-level summary Atmosphere DDRs that have been broken out into specific observational geometries for ease of finding those specific geometries. Atmosphere Model DDRs: The UVVS Atmospheric Model DDRs consist of a series of model fits to data averaged over specific Mercury true anomalies and local times. These model fits, and the parameters provided in the DDRs, are described below in 'Derived Product Overview.' The description is given for Na, but Ca and Mg are similarly fitted. Instrument Overview : The MASCS instrument consists of a small Cassegrain telescope that simultaneously feeds the UVVS and VIRS experiments. The 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 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. Derived Product Overview : This data set consists of data derived from MASCS UVVS Calibrated Data Records (CDR). The Science CDRs are the processed data records used to derive emission or reflectance data used for scientific analysis. The UVVS Science CDRs contain emission data of the UVVS photomultiplier tubes (PMT) at the commanded step of the UVVS grating, which corresponds to a specific wavelength of light. Wavelength range and sensitivity of each PMT at each grating step vary, as documented in the MASCS Calibration Report, MASCS_CAL_RPT.PDF, provided in the DOCUMENT directory. Before the science data can be used for scientific analysis, the count rates in the EDRs must be converted to physical units and the data must be transformed into meaningful physical reference systems. This conversion yields calibrated data which are stored in Calibrated Data Records (CDRs). Surface DDRs: The CDR to surface DDR processing steps include: 1. Filter out non-surface observations. 2. MUV: Bin spectral radiance to 2 nm over the wavelength range 210-300 nm, then derive reflectance. FUV: Bin the spectral radiance to 1 nm at 121.6 nm and 130.4 nm, then derive reflectance. 3. Apply photometric normalization. Geometry-classified Atmosphere DDRs: The CDR data for Na, Ca, and Mg are filtered by observational category and combined according to Mercury year to create the geometry-classified Atmosphere DDR files. The general processing steps from the CDR to the geometry-classified Atmosphere DDR level include: For each of: a) Dayside limb altitude profiles b) Dayside and nightside limb drift profiles c) Night side tail sweep profiles carry out the following: 1. Filter CDRs for a specified species and observational category. 2. Order as a time series, which keeps individual altitude profiles together. Additional, non-standard corrections were applied to certain Mg and Ca data (see below under 'Data Coverage and Quality') and are outlined in the UVVS_PROCESSING_UPDATES_PDS16.PDF file in the DOCUMENT directory. Orbit-level Summary Atmosphere DDRs: The CDR data for Na, Ca, and Mg are combined according to orbit number to create the orbit-level Summary Atmosphere DDR files. All observation types are included. The processing steps from the CDR to the orbit-level Summary Atmosphere DDR level include: 1. Order all data for a given species on a given orbit as a time series. Atmospheric Model DDR: The model employed is adapted from the model developed by Chamberlain [1963]. The temperature and density of the dayside sodium exosphere were found by fitting the estimated column densities from individual limb scans. The fit applies only to the lower 700-1000 km of the exosphere, which is relatively cold and dense compared to the exosphere at higher altitudes. The DDRs give the averages of these fits as a function of true anomaly in 5 degree increments. The column density N (cm^-2) is derived from radiance I (kR) using N : I/(g 10^6) (1) The g-value is the rate (s^-1) at which an atom scatters sodium D1 and D2 solar photons. It depends on distance from, and radial velocity relative to, the Sun. The sodium atoms have a distribution of speeds, but because this distribution is relatively narrow for the low-altitude, low-temperature portion of the exosphere described in this data product, we use Mercury's radial velocity and distance from the Sun to calculate g. The exospheric column density is related to the density via N : KHn (2) where n is the density of the exosphere at the line-of-sight tangent point, H is the scale height of the exosphere, and K is the ratio between the line-of-sight column density and the vertical column density (~Hn) and given, approximately, by [pi*r/(2H)]^(1/2). These formulas come from Chamberlain [1963]. The density is approximated by n : n0e^-(U/kT) (3) where U is the gravitational potential energy due to gravity and photon acceleration, T the temperature, and n0 the surface density (see Feynman [1963] for a general discussion of this formula). The temperature and surface density are the free parameters of our fits to the limb scans and are provided in the DDR. Photon acceleration (also called photon pressure or radiation pressure) is an antisunward acceleration due to the resonant scattering of sunlight. It is directly proportional to the g-value. At Mercury, for sodium, it can be nearly half as large as surface gravity (e.g., Wang and Ip [2011]). For that reason we included it along with the gravitational potential term in Eq. (1), so that the potential energy is written as U : GMm/r + mbrcos(theta) (4) as described in Bishop [1985], where b is the photon acceleration, theta is the angle between the local radial vector and the Mercury-Sun axis, G is the gravitational constant, M is the mass of Mercury, m is the mass of a sodium atom, and r is the distance from Mercury's center. For each limbscan, because they all have line-of-sight tangent points near the equator, theta is derived, approximately, by the angular distance from noon as measured by the local time provided in the DDR. The scale height, used in the formulas above and provided in the data product, is defined by H : n/(dn/dr) : kT/( GMm/r^2 + mbcos(theta) ) (5) Note that in the absence of photon pressure and ignoring the radial variation in gravity, this definition reduces to the classic kT/ma, where a is gravitational acceleration. Alternately, we can write H as H : kT/m(a + bcos(theta) ) (6) where the parenthetical term in the denominator can be seen as a sum of two terms, the gravitational term and the radial component of the photon pressure. This scale height (measured in km) is also provided in the DDR. Coordinate Systems : MASCS UVVS data are represented in the following coordinate systems: * Planetocentric body fixed: The MBF coordinate system is defined by the planetocentric position, Cartesian X, Y, Z coordinates related to the planetocentric distance, latitude measured positive northward from the equator, and longitude measured positive eastward from the prime meridian. * Cartographic: Surface observations use IAU planetocentric system with East longitudes being positive for planetary surfaces. The MESSENGER-derived reference system (pck00010_msgr_v21.tpc) for cartographic coordinates and rotational elements was used for computing latitude and longitude coordinates of planets. Data : Surface DDRs: There are two surface DDR data products associated with each UVVS observation set: a science header table, showing the instrument command parameters for a given observation, and a science data table, showing counts, derived science data, and pointing information for each bin (2 nm for MUV, 1 nm for FUV) of an observation. The surface DDRs are in binary table format, and each is described by a detached PDS label. The label points to an associated format file that defines the fields of the binary table contained within the data file. There are four types of spectra stored in each surface DDR science data file: IOF_BIN_DATA (table column 14), PHOTOM_IOF_BIN_DATA (table column 15), IOF_BIN_NOISE_DATA (table column 16), and PHOTOM_IOF_BIN_NOISE_DATA (table column 17). Geometry-classified Atmosphere DDR: There are nine geometry-classified UVVS atmosphere DDR data products per Mercury year (as defined above), one for each species (Na, Ca, Mg) and for each observation category (dayside limb altitude profile, dayside and nightside limb drift profile, and nightside tail sweep profile). Data from the MASCS housekeeping EDR product generated by the MASCS instrument, which is the same for both the UVVS and VIRS components of the MASCS experiment, are incorporated into the CDRs, and data from both EDR and CDR are passed through to the DDR. Geometry-classified Atmosphere DDRs for each species and observation category consist of individual files spanning one Mercury year from true anomaly 0 to 360 degrees. Fractional years (including the beginning of the orbital phase and the end of mission) will not contain data for all true anomaly values. There are two types of data stored in each science file: RADIANCE versus WAVELENGTH (spectra) and TOTAL_RADIANCE in each observed emission line [total radiance integrated over the emission line(s) as measured at each tangent altitude]. Orbit-level Summary Atmosphere DDR: There are three orbit-level Summary UVVS Atmosphere DDR data products per MESSENGER orbit, one for each species (Na, Ca, Mg). Data from the MASCS housekeeping EDR product generated by the MASCS instrument, which is the same for both the UVVS and VIRS components of the MASCS experiment, are incorporated into the CDRs, and data from both EDR and CDR are passed through to the DDR. Orbit-level Summary Atmosphere DDRs for each species consist of individual files spanning one MESSENGER orbit. There are two types of data stored in each science file: RADIANCE versus WAVELENGTH (spectra) and TOTAL_RADIANCE in each observed emission line [total radiance integrated over the emission line(s) as measured at each tangent altitude]. Atmospheric Model DDR: The UVVS Atmospheric Model DDRs consist of average fits to observations at a series of Mercury true anomaly and local times. The model parameters near-surface density, temperature, and scale height are provided. The data are provided in an ASCII table format. There are 3 atmospheric model DDRs for the sodium, magnesium, and calcium models, respectively.
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| DATA_SET_RELEASE_DATE |
2017-05-12T00:00:00.000Z
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| START_TIME |
2011-03-29T01:33:53.000Z
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| STOP_TIME |
2015-04-30T03:01:43.000Z
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| MISSION_NAME |
MESSENGER
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| MISSION_START_DATE |
2004-08-03T12:00:00.000Z
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| MISSION_STOP_DATE |
2015-04-30T12:00:00.000Z
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| TARGET_NAME |
MERCURY
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| TARGET_TYPE |
PLANET
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| INSTRUMENT_HOST_ID |
MESS
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| INSTRUMENT_NAME |
MERCURY ATMOSPHERIC AND SURFACE COMPOSITION SPECTROMETER
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| INSTRUMENT_ID |
MASCS
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| INSTRUMENT_TYPE |
VISIBLE/INFRARED SPECTROGRAPH
UV/VISIBLE SPECTROMETER
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| NODE_NAME |
Geosciences
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| ARCHIVE_STATUS |
ARCHIVED - ACCUMULATING
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| CONFIDENCE_LEVEL_NOTE |
Confidence Level Overview : The MASCS UVVS Derived Data Records (DDRs) consist of derived data converted to physical units and represented in physical coordinate systems. Data presented here are an accurate representation of the UVVS data as received from the spacecraft, and reflect the processing steps from the MASCS UVVS Calibrated Data Record (CDR) to the Derived Data Record (DDR) level as detailed in the documents UVVS_CDR2DDR.TXT and UVVS_PROCESSING_UPDATES_PDS16.PDF located in the DOCUMENT directory. The UTC and MET time tags have been corrected for timing latencies in the instrument so that the UTC and MET correspond to the physical time of the observation. It should be noted that the atmospheric models are intended only as a first-order approximation of the average atmospheric state on the dayside using a well-known and accepted model (the Chamberlain model). However, such models lack some of the relevant physics that are pertinent to the Mercury exosphere. As such, they are excellent starting points for more detailed models but should not be interpreted as a true representation of the actual exosphere. More detailed models are too complicated to provide in any meaningful way. Review : The UVVS DDR was reviewed internally by the MASCS team prior to release to the PDS. PDS also performed an external review of the MASCS UVVS DDRs. Data Coverage and Quality : Data reported are the derived data received from the spacecraft during the orbital mission phases: 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) Mercury Years ------------------------- ----------- ----------- ------------- ORB: Mercury Orbit 04 Mar 2011 17 Mar 2012 1 (partial), (063) (077) 2,3,4, 5 (partial) OB2: Mercury Orbit Year 2 18 Mar 2012 17 Mar 2013 5 (partial), (078) (076) 6,7,8, 9(partial) OB3: Mercury Orbit Year 3 18 Mar 2013 17 Mar 2014 9 (partial), (077) (076) 10,11,12, 13 (partial) OB4: Mercury Orbit Year 4 18 Mar 2014 17 Mar 2015 13 (partial), (077) (076) 14,15,16, 17 (partial) OB5: Mercury Orbit Year 5 18 Mar 2015 30 Apr 2015 17 (partial), (077) (112) 18 (partial) To validate the initial DDR dataset, the MASCS team did the following: * Examined one Mercury year of data for each DDR product type. - Checked all data columns for format and sanity numbers. - Compared calibration numbers for earlier independent analysis before DDR development. - Compared pointing information (vectors, latitudes, longitudes, distances, angles) to previous independent solutions. * Spot-checked additional data sets from other Mercury years. The orbital DDR dataset is evaluated on an ongoing basis, checking for completeness and data integrity. MASCS UVVS data were collected during all phases except Venus 1 Flyby. DDR data are derived from orbit only. Data quality information for DDR observations are available in the DQI of matching CDRs. Correction of Magnesium Dayside Limb Scans A systematic instrument effect on the UVVS data has been found in the dayside observations. This effect, likely due to a scattering problem of unknown origin, mimics a constant background that shows a dependence on altitude, local time and true anomaly angle. A correction for this effect on magnesium data in the dayside limb scans (LS) has been developed and implemented as described in the file UVVS_PROCESSING_UPDATES_PDS16.PDF, located in the DOCUMENT directory. This effect has no impact on the nightside magnesium tail sweeps (NS). The effect is minimal in the calcium and sodium observations, so these data have not been corrected. Averaging of Low-Altitude Calcium Data At low altitudes, the combination of the calcium emission and the contribution from sunlight reflected off the planet's surface and scattered into the UVVS field of view often led to saturation of the VIS channel. To compensate, the surface slit was used to reduce the overall flux into the UVVS instrument, but this also had the effect of lowering the signal-to-noise ratio (SNR) of the calcium detections. To offset the SNR decrease, calcium spectra during these low-altitude observations that use the surface slit have been averaged to enhance the SNR of the calcium signal. The details of this procedure are found in the file UVVS_PROCESSING_UPDATES_PDS16.PDF, located in the DOCUMENT directory. This issue was not a problem for magnesium or sodium because the UVVS sensitivity and the solar flux at magnesium wavelengths were both significantly less, whereas the sodium signal, even in the surface slit, was still strong enough that averaging was not needed. Limitations : This data set is derived data. The data are received from the spacecraft telemetry and ingested into the MESSENGER Science Operations Center (SOC), then run through the MASCS pipeline. No data uncharacterized gaps have been identified for any of the MASCS operational periods. The data have been calibrated to the best possible level; however, there are temperature-dependent effects in the background removal and wavelength calibration that are difficult to correct with 100% certainty. The user is warned that these effects may sometimes result in false positives in the calibrated radiance (i.e., false detections). Care should be exercised in using the data, particularly when results are anomalous in appearance. It is noted that the UVVS DDRs represent the best calibrated set of exosphere observations for Na, Ca, and Mg. Because of issues that remain in the CDRs (as stated in the confidence notes), users are **STRONGLY ENCOURAGED** to use the DDRs for scientific analysis rather than the CDRs.
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| CITATION_DESCRIPTION |
Izenberg, N., MESSENGER E/V/H MASCS 4 UVVS DERIVED DATA V1.0, MESS-E/V/H-MASCS-4-UVVS-DDR-V1.0, NASA Planetary Data System, 2013.
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| ABSTRACT_TEXT |
Abstract : This data set consists of the MESSENGER MASCS UVVS derived data records, also known as DDRs. There are three types of UVVS DDRs: surface, atmosphere, and atmospheric model. There are two surface DDR data products associated with each UVVS observation set: a science header table and a science data table. There are nine geometry-classified atmosphere DDR data products, consisting of three different observation types for each of sodium (Na), calcium (Ca), and magnesium (Mg). There are three orbit-level summary atmosphere DDR data products, one each for Na, Ca, and Mg. There are 3 atmospheric model data products, one each for observations of Na, Ca, and Mg.
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| PRODUCER_FULL_NAME |
NOAM IZENBERG
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| SEARCH/ACCESS DATA |
Geosciences Web Services
Mercury Orbital Data Explorer
ATMOS direct data access
Geosciences Online Archives
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