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Hubble Space Telescope
Images Near Best Focus

The images display NGC 3603, the cluster used in the focus monitoring programs, taken at a PAM position that brings the focus as close as possible to the detector position. In the case of Camera 3, this is, of course, on the extreme end of the PAM range. The image of NGC 3606 is shown at the PAM position of about -8 mm. Much better image quality was achieved at the PAM setting of -9.5 mm.