WFC3 Flight Detector Alignment Characterization in Thermal-Vacuum Test #1

We have performed an initial assessment of the alignment status of the UVIS-1and IR-2 flight detectors as mounted in WFC3 during the first instrument-level thermal-vac test. Both detectors are found to be aligned out of tolerance, indicating errors in the transfer of surrogate alignment information to the flight articles. Measurements made at various times through the thermal vac test, with the instrument in different thermal environments, demonstrate little variation. However, for reasons that remain unclear, the alignment of the UVIS detector, particularly its tilt about the X-axis, varied significantly in measurements made in ambient before and after thermal-vac testing. The UVIS-1 detector alignment must be modified to remove the residual alignment error. The IR-2 detector is not expected to fly; the measured alignment error must be used to set the alignment of the flight IR detector package, when it is completed at Ball Aerospace.