Glossary: Viking

ALL

  • 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 "straight down", thus, the emission angle is close to 0°.
  • Filter Name
    • The commonly used name for a camera filter. Examples include BB1, SURVEY, RED, and IR1.
  • Gain Mode ID
    • A number indicating which preset gain value was used in the analog to digital conversion process. The gain was a multiplicative factor applied to the measured value. The Viking Lander cameras had 6 commandable gains.
  • ID
    • The product_id element provides a unique identifier for a data product. Product_id for a Viking Lander EDR image has the following form: lcxnnn-xxx, where l is the lander number, c is the camera number, x is a letter sequence from A to J, nnn is a number sequence from 000 to 255, and xxx is an abbreviation for the filter. An example is 12A001-BB1.
  • Image Id
    • The product_id element provides a unique identifier for a data product. Product_id for a Viking Lander EDR image has the following form: lcxnnn-xxx, where l is the lander number, c is the camera number, x is a letter sequence from A to J, nnn is a number sequence from 000 to 255, and xxx is an abbreviation for the filter. An example is 12A001-BB1.
  • Image ID(s)
    • The product_id element provides a unique identifier for a data product. Product_id for a Viking Lander EDR image has the following form: lcxnnn-xxx, where l is the lander number, c is the camera number, x is a letter sequence from A to J, nnn is a number sequence from 000 to 255, and xxx is an abbreviation for the filter. An example is 12A001-BB1.
  • Image Volume Id
    • The volume_id element provides a unique identifier for a data volume. Example: VL_0001.
  • 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 and an angle of 90 degrees means the Sun is on the horizon. Daytime infrared images typically have incidence angles between approximately 0-90 degrees and nighttime infrared images typically have incidence angles greater than 90 degrees.
  • Instrument
    • This element lists the full name of an instrument that acquired the data product. Values are CAMERA_1 or CAMERA_2.
  • 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.
  • Line Resolution
    • The vertical size of a pixel at the center of the image as projected onto the surface of the target; units are given with the value.
  • Local Solar Time
    • 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) 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.
  • Mission Phase
    • The mission_phase_name is the commonly- used identifier for a given phase during a mission. Examples are PRIMARY_MISSION and EXTENDED_MISSION.
  • 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.
  • Note
    • A short note that describes either why an image was acquired or a comment about its content.
  • Orbit
    • Spacecraft orbit during which this image was observed.
  • Sample Resolution
    • The horizontal size of a pixel at the center of the image as projected onto the surface of the target; units are given with the value.
  • 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.
  • 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
    • This element lists the full name of a spacecraft that acquired the data product. Values are VIKING_LANDER_1 OR VIKING_LANDER_2.
  • Target Name
    • This element identifies the target. Values are MARS, SUN, PHOBOS, DEIMOS, or N/A. The N/A value is used for scan verification and internal calibration images.