PROCEDURE:

The instrument was mounted on a high precision (0.001° resolution) 2-axis gimbal aimed at a 45 cm diameter, 229 cm focal length parabolic collimator mirror.  A 0.25mm diameter pinhole aperture, located at the mirror’s focal point produce a reference beam that simulates a ‘star source’ with a 0.006° divergence.

Maps of the VIRS FOV were used to determine the VIRS boresight and field of view and to infer the telescope point spread function (PSF).  The VIRS FOV (nominal 0.023° circle) was measured by stepping the star source across the telescope image plane to obtain 121 spectra over an 0.08° square grid (11 x 11 images separated by 0.008°).  The zero position for the grid was set to the center of the UVVS surface slit.

FILE DESCRIPTIONS:

  BACKGROUND_RASTER33__20030417_225954.rec
Initial dark scan.

there are 121 (11x11) signal scans with the name:
  v____________________AAAAAAAA_BBBBBB.rec
where:
AAAAAAAA is the date in YYYYMMDD format.
BBBBBB is the time in HHMMSS format.

  position_info.txt
An ASCII file containing the angular position of the instrument at each data sample.  The center of the grid is at +0.380degrees in X' and +0.025degrees in Y', where X' and Y' represent the arbitrary logical coordinate system set up for this measurement.  These measurements are relative to the FOV center of the UVVS surface slit, located at (0,0).  These directions can be related to the right-handed spacecraft coordinate system (where the instruments are pointed in the +Z-direction, and +Y is the anti-solar direction).  Positive values of X' represent angles measured in the X-Z plane, toward the +X axis relative to the +Z axis.  Positive values of Y' represent angles measured in the Y-Z plane toward the -Y axis relative to the +Z axis.  The grid was sampled in a raster-style (zig-zag) but the position information in this data file was written so that the position following the last in a row is at the beginning of the next row.