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The state of the focus and image quality of the Spitzer Space Telescope as measured in orbit

Gehrz, Robert D. and Romana, Edward A. and Hoffmann, William F. and Schwenker, John P. and Mentzell, John E. and Hora, Joseph L. and Eisenhardt, Peter R. and Brandl, Bernhard R. and Armus, Lee and Stapelfeldt, Karl R. and Hines, Dean C. and Mainzer, Amanda K. and Young, Erick T. and Elliott, David G. (2004) The state of the focus and image quality of the Spitzer Space Telescope as measured in orbit. In: Optical, Infrared, and Millimeter Space Telescopes. Proceedings of SPIE. No.5487. Society of Photo-optical Instrumentation Engineers (SPIE) , Bellingham, WA, pp. 166-176. ISBN 9780819454195.

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We describe the process by which the NASA Spitzer Space Telescope (SST) Cryogenic Telescope Assembly (CTA) 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 strategy was developed to determine the focus position through a program of passive imaging during the observatory cool-down time period. A number of analytical diagnostic tools were developed to facilitate evaluation of the state of the CTA focus. Initially, these tools were used to establish the in-orbit focus position. These tools were then used to evaluate the effects of an initial small exploratory move that verified the health and calibration of the secondary mirror 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 CTA Point Spread Function (PSF) at different channel wavelengths and demonstrate that the telescope achieved diffraction limited performance at a wavelength of 5.5 μm, somewhat better than the level-one requirement.

Item Type:Book Section
Related URLs:
URLURL TypeDescription
Gehrz, Robert D.0000-0003-1319-4089
Hora, Joseph L.0000-0002-5599-4650
Armus, Lee0000-0003-3498-2973
Stapelfeldt, Karl R.0000-0002-2805-7338
Hines, Dean C.0000-0003-4653-6161
Additional Information:© 2004 Society of Photo-optical Instrumentation Engineers (SPIE). The research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). RDG was funded for this work by NASA through the JPL SIRTF Project Office.
Funding AgencyGrant Number
Subject Keywords:Spitzer Space Telescope (SST), SIRTF, IRAC, IRS, MIPS, noise-pixels, cryogenic, telescope, focus
Series Name:Proceedings of SPIE
Issue or Number:5487
Record Number:CaltechAUTHORS:20190115-094649319
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Official Citation:Robert Douglas Gehrz, Edward A. Romana, William F. Hoffmann, John P. Schwenker, John Eric Mentzell, Joseph L. Hora, Peter R. Eisenhardt, Bernhard Rainer Brandl, Lee Armus, Karl R. Stapelfeldt, Dean C. Hines, Amanda K. Mainzer, Erick T. Young, David G. Elliott, "The state of the focus and image quality of the Spitzer Space Telescope as measured in orbit," Proc. SPIE 5487, Optical, Infrared, and Millimeter Space Telescopes, (12 October 2004); doi: 10.1117/12.551930
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92277
Deposited By: Tony Diaz
Deposited On:15 Jan 2019 23:10
Last Modified:01 Nov 2019 22:37

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