Keeping the Hubble Space Telescope in focus

Colin Cox; Matthew Lallo

doi:10.1117/12.924900

21 September 2012 Keeping the Hubble Space Telescope in focus

Colin Cox, Matthew Lallo

Proceedings Volume 8442, Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave; 844237 (2012) https://doi.org/10.1117/12.924900
Event: SPIE Astronomical Telescopes + Instrumentation, 2012, Amsterdam, Netherlands

Abstract

The Hubble Space Telescope is a Ritchie-Chrétien optical design with a main primary concave mirror followed by a convex secondary. The focus is determined by the position of each of these two mirrors. The truss containing them is made of graphite epoxy which has very low thermal expansion. Nevertheless, temperature variations do cause the mirror separation to vary by several microns within an orbit. Additionally, outgassing of water vapor causes a long-term shrinkage which soon after launch in 1990 varied by more than 2 microns per month. This necessitated adjusting the position of the secondary mirror every few months. Currently this rate is greatly reduced and adjustments are needed less than once per year. The focus is monitored monthly to continually assess the need for such adjustments. The measurements have been used to develop models to predict the focus at times between measurements to assist in the analysis of observations. Detailed focus knowledge is of value in photometry, coronagraphy and image deconvolution. The various focus models that have been applied so far are described with an evaluation of their performance. Continuing attempts to refine the model will be discussed.

Citation Download Citation

Colin Cox and Matthew Lallo "Keeping the Hubble Space Telescope in focus", Proc. SPIE 8442, Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave, 844237 (21 September 2012); https://doi.org/10.1117/12.924900

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available