WTTM Optical Alignment with WIYN IAS

Using a bright star, we determined the position of the telescope's optical axis, and MiniMo center on the WTTM CCD.  To achieve this, we pre-determined the center of rotation for the WIYN port which defines the telescope's optical axis.  Also, using MiniMo, we determined it's center position relative to the IAS guide probe and used this fiducial to then transfer it's location onto WTTM's CCD.

Also determined was the reliability of a star's position as effected by the WTTM's pickoff mirror's insertion and removal.  This was achieved by first guiding with the WIYN IAS, and repeatedly removing/inserting the WTTM pickoff mirror.
 

WTTM Pixel
X, Y
WTTM CCD Center 1023.5, 1249.5
Telescope Optical Axis (center of NIR rotation) 1097, 1198
MiniMo Center 1302, 1249
WTTM PickOff Mirror: Repeatability in Positioning removal/insertion +/- 3pixels

Also, as noted in the flexure report, we do see a dependency of position, on the CCD focal surface, as a function of rotator angle.  Fortunately, this effect will be less than one pixel for most circumstance, but expect a ~2-pixel shift for rotation angles that change by more than 90d.

Note also that we do not expect these position to remain constant over time.  The removal and installation of the CCD dewars shift these positions slightly, of order 5-10pixels.