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MSI/NIS MOON 2  COALIGNMENT TEST: |
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see plots:  /pre_eros/earthmoon_flyby/coalignrow.gif
                                      coaligncolumn.gif

General: We do two scans here. For the first one we position the center of NIS mirror position 75
fov  .75 deg from the center of the lit portion of the moon in the -z direction.  The scan then
moves the NIS fov in the +z direction (parallel to the short dimension of the NIS narrow fov) at a
rate of .002 deg/sec so it travels through the center of the lit portion of the moon and beyond by
.75 deg over 750 sec . Total scan length is 1.5 deg. We acquire one MSI image every 50 seconds
(15 images total) during the slew (one every .1 degrees).  NIS Sequence 8 begins execution at the
start of the scan and acquires 1 individual spectrum each second for the duration of the scan. The
aperture alternates between narrow and wide every 25 seconds, starting with the narrow. 

For the second scan, MSI and NIS data acquisition is exactly the same as above except the start
of the scan has the center of NIS 75  .75 deg in the -y direction from the center of the lit portion
of the moon.  The fov is scanned in the +y direction (parallel to the short dimension of the NIS
narrow fov) for 1.5 degrees exactly through the center of the lit portion of the moon and beyond
another .75 deg. 

To make slewing symmetrical about nadir, we define the boresight in a similar fashion as in the
NIS Moon Radiometry observation.  First, we define the boresight as center of NIS 75. Center of
NIS 75 is 18.9 'short' MSI pixels (.1038438 deg) toward the +z axis from x', and 1.5 'long' MSI
pixels (.0139074 deg) toward the -y axis from x'.  (A 'short' pixel is .000095895 microrad, a 'long'
pixel is .00016182 microrad).  Then, on top of that, we make boresight point a half moon radius
(.0277610 deg at the time this observation executes) toward -z so that when x' is slewed or
pointed relative to nadir, the center of NIS 75 will slew or point relative to the center of the lit
portion of the moon.  Summing the two, make boresight .0760828 deg toward +z, and 0.0139074
deg toward -y from x'.  Boresight = (.9999991, -.0002427, .0013279).