Glossary: THEMIS

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  • ABR
    • Apparent Brightness Record - The ABR is derived from band 3 of a VIS-RDR QUBE (or first available band of the highest calibration product available). See SDPSIS for a summary of the image processing. This file is a PDS IMAGE object with an attached PDS label.
  • ALB
    • Visible projected ALBedo record - The ALB is derived from band 3 of a VIS-RDR QUBE. See GEOMETRY for a summary of the image processing. This file is a PDS IMAGE object with an attached PDS label.
  • Albedo Max
    • Maximum lambert albedo value for band-3 of the VIS-ALB image.
  • Albedo Min
    • Minimum lambert albedo value for band-3 of the VIS-ALB image.
  • Avg Albedo
    • Average lambert albedo value for band-3 of the VIS-ALB image.
  • Avg Dust Opacity
    • Average derived dust opacity (9µm) for a warm, daytime IR image; typical values range from 0.05 to 0.25.
  • Avg Surface Temp
    • Average surface temperature (in degrees Kelvin) derived from Band 3-9 in the IR image.
  • Avg Water Ice Opacity
    • Average derived water ice opacity (11µm) for a warm, daytime IR image; typical values range from 0.0 to 0.15.
  • Band Bin Filter Number
    • List of filter numbers corresponding to each layer (band) contained in the image; up to 10 entries possible for IR images and up to 5 entries possible for VIS images. The filter number describes the physical location of the band in the detector array; filter 1 is on the leading edge of the detector array. For IR images, Filter Numbers = Band Numbers; for VIS images Filter Numbers != Band Numbers (see SDPSIS).
  • Band Numbers
    • Band numbers correspond to each layer contained in an image; up to 10 bands available in an IR image and up to 5 bands available in a VIS image. Also known as Bands or Band_Bin_Band_Numbers (see SDPSIS).
  • Bands
    • Band numbers correspond to each layer contained in an image; up to 10 bands available in an IR image and up to 5 bands available in a VIS image. Also known as Band Numbers or Band_Bin_Band_Numbers.
  • BEQR
    • BEQR images are BROWSE images generated from a representative band of the EQuiRectanglar projected image. BROWSE images are usually available in the PNG file format. See THEMIS GEOMETRY for more information about projected images.
  • BPOL
    • BPOL images are BROWSE images generated from a representative band of the POLar Stereographic projected image. BROWSE images are usually available in the PNG file format. See THEMIS GEOMETRY for more information about projected images.
  • BSNU
    • BSNU images are BROWSE images generated from a representative band of the SiNUsoidal projected image. BROWSE images are usually available in the PNG file format. See THEMIS GEOMETRY for more information about projected images.
  • BTR
    • Brightness Temperature Record - The BTR is derived from band 9 of a IR-RDR QUBE (or first available band of the highest calibration product available). See SDPSIS for a summary of the image processing. This file is a PDS IMAGE object with an attached PDS label.
  • BWS
    • BroWSe images are a reduced size, easily viewed representation of the image; useful for identifying products of interest. BROWSE images are usually available in the PNG file format.
  • Center Latitude
    • This is the approximate latitude on the planet Mars of the image center. All values are based on the IAU 2000 aerocentric model of Mars with east positive longitude.
  • Center Longitude
    • This is the approximate longitude on the planet Mars of the image center. All values are based on the IAU 2000 aerocentric model of Mars with east positive longitude.
  • DCS
    • Decorrelation Stretch Image - These four panel images include three DCS images and a surface temperature image. The DCS images are generated by stretching correlated radiances of the following band combinations: band 8, 7, 5 (left DCS panel); bands 9, 6, 4 (middle DCS panel); and bands 6, 4, 2 (right DCS panel). See THEMIS GEOMETRY for more information.
  • Description
    • Description of the image target assigned by the mission planner. When searching by description, all text entered into the field will be directly compared with available descriptions.
  • Duration (sec)
    • The length of time (in seconds) requried to collect all frames of all bands in the downlinked image; typical values range from 0.5 to 450.
  • Dust Opacity
    • Average derived dust opacity (9µm) for a warm, daytime IR image; typical values range from 0.05 to 0.25.
  • EDR
    • Experiment Data Record - This file contains the raw THEMIS science data at the full resolution returned from the spacecraft, time ordered, with duplicates and transmission errors removed. This file is a PDS SPECTRAL_QUBE object with an attached PDS label. See THEMIS SDPSIS for more information.
  • Emission Angle
    • Measured from the center of the image, this is the angle between THEMIS and a "normal" drawn perpendicular to the planet's surface. In most cases, THEMIS is looking nadir (straight down), thus, the emission angle is close to 0°.
  • EQR
    • Equirectangular Geometrically Registered Record - This file contains the geometric projection of the RDR standard data product; the data is stored as a multispectral ISIS CUBE file and associated with a PDS-style, detached label. Note that additional manipulation of the source data may invalidate the calibrated radiance values. See THEMIS GEOMETRY for more information.
  • GEO
    • Geometrically Registered Record - This file contains the geometric projection of the RDR standard data product; the data is stored as a multispectral ISIS CUBE file and associated with a PDS-style, detached label. Note that additional manipulation of the source data may invalidate the calibrated radiance values. See THEMIS GEOMETRY for more information.
  • Geometry Level
    • Description of the geometry kernels used by the ISIS software when generating geometric information for this image. Usual values include: “Not Available”, “Predicted”, “Reconstructed”, “Nadir pointing assumed”, or “Off Nadir pointing assumed”
  • ID
    • A unique identifier for each observation commanded; follows the pattern Xoooooiii, where:
      • X is the observation type (I, R, S, or V)
      • ooooo is the zero padded, 5-digit orbit number
      • iii is the zero padded, 3-digit image number
  • Image ID
    • A unique identifier for each observation commanded; follows the pattern Xoooooiii, where:
      • X is the observation type (I, R, S, or V)
      • ooooo is the zero padded, 5-digit orbit number
      • iii is the zero padded, 3-digit image number
  • Image Rating
    • Subjective assessment of image quality ranging from unusable (1) to good (7); assesment includes consideration of exposure, missing lines, instrument noise, and atmospheric features. Note that image_rating=7 occur rarely; most users find image_ratings 3 to 6 acceptable for their studies.
  • Image Type
    • The type of image, i.e. Visible (VIS) or Infrared (IR)
  • Incidence Angle
    • Calculated for the center of each image, this is the angle between the Sun and a line drawn normal to the surface of the planet at the time the image was acquired.
      • an angle of 0 degrees means the Sun is directly overhead
      • an angle of 90 degrees means the Sun is on the horizon
      • Daytime images typically have incidence angles between approximately 0-90 degrees
      • Nighttime infrared images typically have incidence angles greater than 90 degrees
  • IR Calibration Flag
    • This flag indicates that problems may have been encountered during the IR calibration routine and the user is advised to review the quality of the calibration. The flag is triggered by image saturation or under-saturation, length of time between the image and the shutter image, quality evaluation of the shutter image, and yaw angle of the Odyssey spacecraft.
  • IR Surface Temperature (K)
    • Average surface temperature (in degrees Kelvin) derived from Band 3-9 in the IR image.
  • Latitude (North)
    • This is the approximate latitude on the planet Mars of the image center. All values are based on the IAU 2000 aerocentric model of Mars with east positive longitude.
  • Local Time (24.0 hr)
    • This is the local time on Mars at the center of the image relative to a division of the martian day into 24 equal parts. A martian day is slightly longer than 24 hours and 37 minutes long.
      • "DAY" images are those with a local time of 08:00-20:00 (8am-8pm)
      • "NIGHT" images are those with a local time of 00:00-07:59 or 20:01-24:59 (0:00-7:59am or 8:01-11:59pm).
      • For orbits before 55600, the orbit descending node is generally asociated with DAY images; after orbit 55600, the orbit ascending node is generally associated with DAY images
      Commonly used as an abbreviation for "Mars Local Solar Time".
  • Longitude (East)
    • This is the approximate longitude on the planet Mars of the image center. All values are based on the IAU 2000 aerocentric model of Mars with east positive longitude.
  • Mars Year
    • The Mars year during which this image was collected. Following the convention established in Clancy [JGR April 2000, doi:10.1029/1999JE001089], the first Themis mapping images were collected during Mars year 25.
  • Max Brightness Temperature
    • Maximum brightness temperature value calculated for IR-BTR of this image.
  • Maximum Thermal Inertia
    • Max thermal ineratia, derived using Keiffer's KRC thermal model. Model allows for inertia values between 20 and 2000.
  • Min Brightness Temperature
    • Minimum brightness temperature value calculated for IR-BTR of this image.
  • Minimum Thermal Inertia
    • Min thermal ineratia, derived using Keiffer's KRC thermal model. Model allows for inertia values between 20 and 2000.
  • MOLA Avg
    • The average elevation value at the center of the image; values are derived from a 2 pixel per degree MOLA elevation map.
  • MOLA Elevation (km)
    • The average elevation value at the center of the image; values are derived from a 2 pixel per degree MOLA elevation map.
  • North Azimuth Angle
    • The clockwise angle from an imaginary three o'clock axis with the origin at the center of a pixel at the center of the image.
      • a value greater than 180 indicates that the image was acquired on the orbit descending node
      • a value less than 180 indicates that the image was acquired on the orbit ascending node
      • When displayed after projection with North-Up, equatorial descending node images are oriented like this "/"; ascending node images are oriented like this "\"
  • orbit
    • Spacecraft orbit during which this image was observed.
  • PBT
    • Projected Brightness Temperature - The PBT is derived from band 9 (or first available band) of a projected IR-GEO CUBE. See GEOMETRY for a summary of the image processing. This file is a PDS IMAGE object with an attached PDS label.
  • Percent Missing
    • Percent of total lines missing from this image; valid values range from 0 to 100, where 100 indicates complete data loss.
  • Pitch
    • A non-zero value indicates spacecraft rotation during image collection; for the ODY spacecraft, a positive pitch angle indicates a right hand rotation around the orbit normal direction. See also Spacecraft_Orientation and/or Spacecraft_Pointing_Mode.
  • Pointing Mode
    • Odyssey pointing mode during image collection; most common modes are NADIR and OFF-NADIR. See ODY Orientation & Pointing for a full description of all valid modes.
  • POL
    • Polar Stereographic Geometrically Registered Record - This file contains the geometric projection of the RDR standard data product; the data is stored as a multispectral ISIS CUBE file and associated with a PDS-style, detached label. Note that additional manipulation of the source data may invalidate the calibrated radiance values. See THEMIS geometry.pdf for more information.
  • Processing Stage
    • THEMIS standard data product abbreviations: EDR, RDR, ABR, BTR, GEO (EQR, POL, SNU), PBT, ALB, DCS, RGB. See Glossary entries or SDPSIS for more information.
  • Product Modification Date
    • Date of the most recent modification to any product of this THEMIS image. This timestamp is particularly useful for finding image products that have been reprocessed since their original release.
  • RDR
    • Reduced Data Record - This file contains the radiometrically calibrated version of the THEMIS EDR standard data products. This file is a PDS SPECTRAL_QUBE object with an attached PDS label. See THEMIS SDPSIS for more information.
  • Release ID
    • Identification of the original public release of this THEMIS image. See Release text for more information.
  • Resolution (km)
    • The vertical size of a pixel (or line) at the center of the image as projected onto the surface of the target; units are given with the value. The nominal resolution for an IR image is 100 m/pixel and for a VIS image is 18 m/pixel.
  • RGB
    • (Red Green Blue) Visible False Color Composite image. The RGB is derived from bands (4,2,1) of a VIS-GEO image; see THEMIS GEOMETRY for more information.
  • Roll Angle (degrees)
    • A non-zero value indicates spacecraft rotation during image collection; for the ODY spacecraft, a positive roll angle indicates a right hand rotation around the spacecraft velocity vector. See also Spacecraft_Orientation and/or Spacecraft_Pointing_Mode.
  • Slant Distance
    • This number is similar to the spacecraft altitude, but also takes into account the emission angle; if the emission angle is 0 then this number is the same as the spacecraft altitude. If the emission angle is much greater than 0, then the "slant distance" to the surface at the center of the image is also greater than the spacecraft altitude.
  • SNU
    • Sinuoidal Geometrically Registered Record - This file contains the geometric projection of the RDR standard data product; the data is stored as a multispectral ISIS CUBE file and associated with a PDS-style, detached label. Note that additional manipulation of the source data may invalidate the calibrated radiance values. See THEMIS GEOMETRY for more information.
  • Solar Distance
    • The distance between Mars and the Sun at the time this image was acquired; given in Astronomical Units.
  • Solar Longitude
    • This is the position of Mars relative to the Sun measured in degrees from the vernal equinox (start of northern Spring). This number is used as a measure of martian seasons:
      • Northern Spring/Southern Autumn start at 0°
      • Northern Summer/Southern Winter start at 90°
      • Northern Autumn/Southern Spring start at 180°
      • Northern Winter/Southern Summer begin at 270°
      Also known as heliocentric longitude and abbreviated Ls.
  • Spacecraft Orientation
    • Odyssey orientation during image collection; described as an angle (in degrees) of rotation away from nadir around the three axis spacecraft frame of reference (PITCH, ROLL, YAW). See ODY Orientation & Pointing for more information.
  • Start Time
    • The time of data acquisition of the leading edge of the detector array (filter 1); value is given in spacecraft event time UTC format.
  • Start Time (et)
    • The time of data acquisition of the leading edge of the detector array (filter 1); value is given in spacecraft event time (SCET) ET format.
  • Start Time (sclk)
    • The value of the spacecraft clock at the time of data acquisition of the leading edge of the detector array (filter 1), even if filter 1 is not downlinked; value given in seconds.
  • Start Timestamp
    • The time of data acquisition of the leading edge of the detector array (filter 1); value is given in spacecraft event time UTC format.
  • Summing
    • Spatial average of NxN pixels of data before downlink; summing=1 implies that no spatial averaging has been applied. VIS images have summing modes of 1, 2, and 4; IR images have summing modes of 1-320.
  • TES Albedo Avg
    • Average TES albedo value in image area using TES Albedo map (8ppd; approx lat coverage:87N-87S); provided for comparison to the value derived from the VIS-ALB product for this image.
  • TES Band10 Temp
    • Brightness temperature for (last line, band10) of "TES data" correlated with this IR image during UDDW processing.
  • TES Rock Abundance Avg
    • Average rock abundance in framelet based on TES RockAbundance map (8ppd; lat coverage:60N-60S); given in percent of rocky material with map_null=-10.
  • TES Thermal Inertia Avg
    • Average TES thermal inertia value at center of framelet using TES Thermal Inertia map (2ppd; lat coverage: 62N-77S).
  • THB
    • THumBnail images are browse (BWS) images reduced to 10% of the original file size, and usually available in JPG file format.
  • THM Band10 Temp
    • Brightness temperature for (last line, band10) of THEMIS IR image obtained during UDDW processing.
  • TIN
    • Thermal INertia - This file contains a THEMIS nighttime infrared image processed into thermal inertia values for use in generating a thermal inertia mosaic; the data is stored as a multispectral ISIS2 CUBE file. See Fergason et al, JGR 2006 doi:10.1029/2006JE002735
  • Water Ice Opacity
    • Average derived water ice opacity (11µm) for a warm, daytime IR image; typical values range from 0.0 to 0.15.
  • Yaw Angle (degrees)
    • A non-zero value indicates spacecraft rotation during image collection; for the ODY spacecraft, a positive yaw angle indicates a right hand rotation around the spacecraft nadir vector. See also Spacecraft_Orientation and/or Spacecraft_Pointing_Mode.