PDS: The Planetary Atmospheres Node
Derived Data Record (DDR)
The VIRS data cover a wavelength range from 300 to 1050 nm (VIS) and 850-1450 nm (NIR). The VIRS Derived Data Records (DDRs) consist of data derived from MASCS VIRS Calibrated Data Records (DDR).
The data span Earth, Venus and Mercury fly-bys. Routine orbital observations began on March 29, 2011.
The DDR archive is arranged first according to mission phase: Mercury flyby 1 (mf1), Mercury flyby 2 (mf2) Mercury Year 1-5 (orb, orb2-5). Then by day, which includes UVVS (UV to visible) and VIRS (visible to IR). Within VIRS, the data are subdivided according to VIS and NIR.
Useful Documents
Access to the Derived Data
The DDRs are in binary format and each product is described by a detached PDS label. The files contain 1 spectrum per row and include the corresponding geometry transferred from the calibrated files. Range in longitude and latitude, footprint size, incidence and emission angles and phase angle are included. Detailed descriptions of the parameters can be found in the label directory.
See the VIRS Calibrated and Derived Data Record Software Interface Specification Document for more information.
Quick Look Indices
The following are indices for Specific Mission Phases of the Derived Data for the Visual and IR data phases – Individual files can be selected based on observational parameters and the corresponding URNs submitted below to retrieve the files. These indices contain URN, Start and Stop Times, Sub-Solar Longitude and Latitude, Sub-Spacecraft Longitude and Latitude, Altitude and Phase Angle computed for the Start Time. File size is included. Because the individual files contain varying numbers of spectra, the total observing time included in an individual product varies from under a minute to over 2 hours, limiting the use of these indices. Nevertheless, the parameters can be used to guide initial access to the data.
Selecting Data at the file level
Accessing Binary Files
An IDL tool which translates the CDR binary files is available (See side bar)
The VIRS data cover a wavelength range from 300 to 1050 nm (VIS) and 850-1450 nm (NIR). The VIRS Derived Data Records (DDRs) consist of data derived from MASCS VIRS Calibrated Data Records (DDR).
The data span Earth, Venus and Mercury fly-bys. Routine orbital observations began on March 29, 2011.
The DDR archive is arranged first according to mission phase: Mercury flyby 1 (mf1), Mercury flyby 2 (mf2) Mercury Year 1-5 (orb, orb2-5). Then by day, which includes UVVS (UV to visible) and VIRS (visible to IR). Within VIRS, the data are subdivided according to VIS and NIR.
Useful Documents
Useful documents located in the documents directory
VIRS_TUTORIAL.PDF: MASCS VIRS Tutorial/User's Guide in PDF/A format.
VIRS_CDR_DDR_DAP_SIS.PDF: The MASCS VIRS CDR/DDR/DAP SIS: "MESSENGER MASCS VIRS Calibrated Data Record, Derived Data Record, and Derived Analysis Product Software Interface Specification"
VIRS_EDR2CDR.TXT: Detailed procedures and tables for EDR to CDR calibration.
VIRS_CDR2DDR.TXT: Detailed procedures and tables for CDR to DDR data reduction.
MASCS_CAL_RPT.PDF: The MESSENGER instrument calibration report for MASCS, in Adobe Acrobat format.
VIRS_DARK_ANALYSIS_REPORT_1.PDF: "VIRS IR Dark Analysis Report 1: Operational Changes" Details the evolving understanding of MASCS dark current during Mercury orbit, describing temperature dependence and effects on the NIR data in particular.
VIRS_DARK_ANALYSIS_REPORT_2.PDF: "VIRS IR Dark Analysis Report 2: Calibration Changes". Describes the adjustments to MASCS calibration to improve dark subtraction and account for pixels saturated due to temperature.
VIRS_CALIBRATION_CHANGES_PDS9.PDF: "VIRS Calibration Changes for PDS Delivery 9" Describes the calibration changes implemented to simplify the handling of dark subtractions for VIRS, and an adjustment to the DATA_QUALITY_INDEX provided in the data records.
VIRS_CALIBRATION_CHANGES_PDS11.PDF: "VIRS Calibration Changes for PDS Delivery 11" Describes changes to the calibration procedure that have been implemented to remedy an observed shift in the wavelength scale of the VIRS visible channel.
VIRS_FLATFIELD_REPORT.PDF: "MASCS/VIRS Lamp-Based Flat Field Report" Describes the results of an investigation to derive a flat-field correction for the MASCS VIRS surface observations.
VIRS_CDR_DDR_DAP_SIS.PDF: The MASCS VIRS CDR/DDR/DAP SIS: "MESSENGER MASCS VIRS Calibrated Data Record, Derived Data Record, and Derived Analysis Product Software Interface Specification"
VIRS_EDR2CDR.TXT: Detailed procedures and tables for EDR to CDR calibration.
VIRS_CDR2DDR.TXT: Detailed procedures and tables for CDR to DDR data reduction.
MASCS_CAL_RPT.PDF: The MESSENGER instrument calibration report for MASCS, in Adobe Acrobat format.
VIRS_DARK_ANALYSIS_REPORT_1.PDF: "VIRS IR Dark Analysis Report 1: Operational Changes" Details the evolving understanding of MASCS dark current during Mercury orbit, describing temperature dependence and effects on the NIR data in particular.
VIRS_DARK_ANALYSIS_REPORT_2.PDF: "VIRS IR Dark Analysis Report 2: Calibration Changes". Describes the adjustments to MASCS calibration to improve dark subtraction and account for pixels saturated due to temperature.
VIRS_CALIBRATION_CHANGES_PDS9.PDF: "VIRS Calibration Changes for PDS Delivery 9" Describes the calibration changes implemented to simplify the handling of dark subtractions for VIRS, and an adjustment to the DATA_QUALITY_INDEX provided in the data records.
VIRS_CALIBRATION_CHANGES_PDS11.PDF: "VIRS Calibration Changes for PDS Delivery 11" Describes changes to the calibration procedure that have been implemented to remedy an observed shift in the wavelength scale of the VIRS visible channel.
VIRS_FLATFIELD_REPORT.PDF: "MASCS/VIRS Lamp-Based Flat Field Report" Describes the results of an investigation to derive a flat-field correction for the MASCS VIRS surface observations.
Access to the Derived Data
The DDRs are in binary format and each product is described by a detached PDS label. The files contain 1 spectrum per row and include the corresponding geometry transferred from the calibrated files. Range in longitude and latitude, footprint size, incidence and emission angles and phase angle are included. Detailed descriptions of the parameters can be found in the label directory.
See the VIRS Calibrated and Derived Data Record Software Interface Specification Document for more information.
Quick Look Indices
The following are indices for Specific Mission Phases of the Derived Data for the Visual and IR data phases – Individual files can be selected based on observational parameters and the corresponding URNs submitted below to retrieve the files. These indices contain URN, Start and Stop Times, Sub-Solar Longitude and Latitude, Sub-Spacecraft Longitude and Latitude, Altitude and Phase Angle computed for the Start Time. File size is included. Because the individual files contain varying numbers of spectra, the total observing time included in an individual product varies from under a minute to over 2 hours, limiting the use of these indices. Nevertheless, the parameters can be used to guide initial access to the data.
Mercury Flyby 1
Mercury Flyby 2
Mercury Year 1 Visible
Mercury Year 2 Visible
Mercury Year 3 Visible
Mercury Year 4 Visible
Mercury Year 5 Visible
Mercury Year 1 Near IR
Mercury Year 2 Near IR
Mercury Year 3 Near IR
Mercury Year 4 Near IR
Mercury Year 5 Near IR
Mercury Flyby 2
Mercury Year 1 Visible
Mercury Year 2 Visible
Mercury Year 3 Visible
Mercury Year 4 Visible
Mercury Year 5 Visible
Mercury Year 1 Near IR
Mercury Year 2 Near IR
Mercury Year 3 Near IR
Mercury Year 4 Near IR
Mercury Year 5 Near IR
Selecting Data at the file level
Accessing Binary Files
An IDL tool which translates the CDR binary files is available (See side bar)
