Data Set Overview
      =================
 
      The Telltale wind indicator is a mechanical anemometer designed to
      operate on the Martian surface as part of the meteorological
      package on the NASA Phoenix lander. It consists of a lightweight
      cylinder suspended by Kevlar fibers and is deflected under the
      action of wind. Imaging of the Telltale deflection allows the wind
      speed and direction to be quantified and image blur caused by its
      oscillations provides information about wind turbulence.
 
      The Telltale data set consists of a single comma-delimited ASCII
      table, TELLTALE.CSV, and its PDS label TELLTALE.LBL.
 
      The table contains the following columns:
 
      Sol             Phoenix Sol
 
      LTST            Local True Time given in image header
 
      LMST            Local Mean Solar Time calculated from LTST
 
      v (m/s)         Wind speed in meters/second
 
      dv+ (m/s)       Error in wind speed (positive)
 
      dv- (m/s)       Error in wind speed (negative)
 
      Dir (deg)       Wind direction in degrees given in meteorological
                      convention (0 = from N, 90 = from E, 180 = from S,
                      270 = from W)
 
      dDir (deg)      Error in direction (given in degrees)
 
      Exposure time   Exposure time by SSI in milliseconds
 
      File name       SSI image filename used for the analysis
 
      Processing
      ==========
 
      This data set has been generated by analysis of SSI images of the
      Telltale. The images have been analyzed to determine the position
      of the Kapton     tube in the Telltale reference frame. The shift
      from rest position is calculated, and the wind velocity and errors
      determined from the methods described in [HOLSTEIN-RATHLOU2008,
      GUNNLAUGSSON2008]. The directions are finally converted to
      areographic directions using the orientation of the lander. The
      result is an ASCII table of time, wind velocity and direction,
      errors in wind velocity and directory, and names of SSI images
      used to derive the values.

Confidence Level Overview
      =========================
 
      Estimated errors are included in the table.
 
      Data Coverage and Quality
      =========================
 
      Data coverage during the course of the Phoenix mission is
      dependent on when the Surface Stereo Imager could be used to
      obtain movies of the telltale. This typically occurs one to
      several times per sol. Quality indicators are included in the
      table in the form of wind velocity errors.