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R. D. Gehrz (University of Minnesota), E. A. Romana (JPL Caltech), W. F. Hoffmann (Steward Observatory), J. P. Schwenker (BATC), J. E. Mentzell (GSFC), J. L. Hora (CfA), P. R. Eisenhardt (JPL Caltech), B. R. Brandl (Leiden University), L. Armus, K. R. Stapelfeldt (JPL Caltech), D. C. Hines (Steward Observatory), A. K. Mainzer (JPL Caltech), E. T. Young (Steward Observatory), D. G. Elliott (JPL Caltech)
We describe the process by which the NASA Space Infrared Telescope Facility (SIRTF) cryogenic telescope assembly was brought into focus after arrival of the spacecraft in orbit. The ground rules of the mission did not allow us to make a conventional focus sweep. A number of analytical diagnostic tools were developed to facilitate evaluation of the state of the CTA focus through a program of passive imaging during the observatory cool-down time period. With these tools, the in orbit focus position was first determined. These tools were then used to evaluate the effects of an initial small exploratory move which verified the health and calibration of the secondary focus mechanism. A second large move of the secondary mirror was then commanded to bring the telescope into focus. We present images that show the point spread function (PSF) of the CTA as a function of wavelength and demonstrate that the level one requirement of diffraction limited performance at a wavelength of 6.5 microns was met.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.