Harvard-Smithsonian Center for Astrophysics
XRT E2E Test
Day 20050607 Shift B
Test Conductor E. DeLuca
Shift Scientists M. Weber & J. Scott
Best Focus II --- Verify Best focus position and Centroid on CCD
After moving to the "OPT" (p/y = -2.90',4.57') optimal boresight aligment position, a fine focus scan, per subtest 7 in the procedure, was performed. Each image centroid was fitted with a 2D Gaussian, and the width (i.e., sigma) was determined.
A 2nd degree polynomial was fitted to the data. The fitted minimum determined the Best Focus position for this boresight alignment. This was found to be -850 focus steps (-515 um) from the initial test configuration. A plot of this polynomial fit to the data is provided on this web page.
FOV Optimized Focus (OF) Position
This section of analysis was performed, but the results indicated that the OF position was in the opposite direction from Best Focus than what we expected. Subsequent investigation confirmed this conclusion. Consequently, the results of the OF analysis performed on this day became moot, and the sub-test was re-performed on 20050608, Shift-B.
A new best focus position has been calculated from the fine focus scan by fitting a second order polynomial to the RSS_widths of the 2-D gaussians. The best focus 2-d polynomial fit is below. The x axis is in focus steps with the minumum in the curve at -850 steps or -515 um.
The archive of the old analysis webpage is here.