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Diagnosing Space Telescope Misalignment and Jitter Using Stellar Images

Ma, Zhaoming and Bernstein, Gary and Sholl, Michael and Weinstein, Alan J. (2008) Diagnosing Space Telescope Misalignment and Jitter Using Stellar Images. Publications of the Astronomical Society of the Pacific, 120 (874). pp. 1307-1317. ISSN 0004-6280. doi:10.1086/595724.

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Accurate knowledge of the telescope's point-spread function (PSF) is essential for the weak gravitational lensing measurements that hold great promise for cosmological constraints. For space telescopes, the PSF may vary with time due to thermal drifts in the telescope structure, and/or due to jitter in the spacecraft pointing (ground-based telescopes have additional sources of variation). We describe and simulate a procedure for using the images of the stars in each exposure to determine the misalignment and jitter parameters, and reconstruct the PSF at any point in that exposure's field of view. As a case study, the simulation uses the design of the Supernova Acceleration Probe (SNAP) telescope. Stellar-image data in a typical exposure determines secondary-mirror positions as precisely as 20 nm. The PSF ellipticities and size, which are the quantities of interest for weak lensing are determined to 4.0 × 10^-4 and 2.2 × 10^-4 accuracies, respectively, in each exposure, sufficient to meet weak-lensing requirements. We show that, for the case of a space telescope, the PSF estimation errors scale inversely with the square root of the total number of photons collected from all the usable stars in the exposure.

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Weinstein, Alan J.0000-0002-0928-6784
Additional Information:© 2008. The Astronomical Society of the Pacific. Received 2008 September 17; accepted 2008 October 15; published 2008 November 17. We thank Michael Lampton, Alexie Leauthaud, Bhuvnesh Jain, and Mike Jarvis for useful discussions. Z.M. and G.B. are supported by Department of Energy grant DOE-DE-FG02-95ER40893. G.B. acknowledges additional support from NASA grant BEFS 04-0014-0018 and National Science Foundation grant AST 06-07667. A.W. is supported by the Department of Energy under grant DE-FG02-92-ER40701, and M.S. is supported by U.S. Department of Energy under contract No. DE-AC02-05CH11231.
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG02-95ER40893
NASABEFS 04-0014-0018
NSFAST 06-07667
Department of Energy (DOE)DE-FG02-92-ER40701
Department of Energy (DOE)DE-AC02-05CH11231
Issue or Number:874
Record Number:CaltechAUTHORS:MAZpasp08
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13044
Deposited By: Archive Administrator
Deposited On:17 Jan 2009 01:05
Last Modified:08 Nov 2021 22:35

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