Jason D. Rhodes
The stability of the point-spread function of the advanced camera for surveys on the Hubble Space Telescope and implications for weak gravitational lensing
Rhodes, Jason D.; Massey, Richard J.; Albert, Justin; Collins, Nicholas; Ellis, Richard S.; Heymans, Catherine; Gardner, Jonathan P.; Kneib, Jean-Paul; Koekemoer, Anton; Leauthaud, Alexie; Mellier, Yannick; Refregier, Alexander; Taylor, James E.; Van Waerbeke, Ludovic
Authors
Prof Richard Massey r.j.massey@durham.ac.uk
Professor
Justin Albert
Nicholas Collins
Richard S. Ellis
Catherine Heymans
Jonathan P. Gardner
Jean-Paul Kneib
Anton Koekemoer
Alexie Leauthaud
Yannick Mellier
Alexander Refregier
James E. Taylor
Ludovic Van Waerbeke
Abstract
We examine the spatial and temporal stability of the Hubble Space Telescope's Advanced Camera for Surveys (ACS) Wide Field Camera (WFC) point-spread function (PSF) using the 2 deg2 COSMOS survey. This is important for studies of weak gravitational lensing, where the ability to deconvolve the PSF from galaxy shapes is of paramount importance. We show that stochastic aliasing of the PSF necessarily occurs during "drizzling." This aliasing is maximal if the output-pixel scale is equal to the input-pixel scale. This source of PSF variation can be significantly reduced by choosing a Gaussian drizzle kernel with a size of 0.8 input pixels and by reducing the output-pixel scale. We show that the PSF is temporally unstable, resulting in an overall slow periodic focus change in the COSMOS images. Using a modified version of the Tiny Tim PSF modeling software, we create grids of undistorted stars over a range of telescope focus values. We then use the approximately 10 well-measured stars in each COSMOS field to pick the best-fit focus value for each field. The Tiny Tim model stars can then be used to perform PSF corrections for weak lensing. We derive a parametric correction for the effect of charge transfer efficiency (CTE) degradation on the shapes of objects in the COSMOS field as a function of observation date, position within the ACS WFC field, and object flux. Finally, we discuss future plans to improve the CTE correction.
Citation
Rhodes, J. D., Massey, R. J., Albert, J., Collins, N., Ellis, R. S., Heymans, C., …Van Waerbeke, L. (2007). The stability of the point-spread function of the advanced camera for surveys on the Hubble Space Telescope and implications for weak gravitational lensing. Astrophysical Journal Supplement, 172(1), 203-218. https://doi.org/10.1086/516592
Journal Article Type | Article |
---|---|
Publication Date | Sep 1, 2007 |
Deposit Date | Mar 21, 2013 |
Publicly Available Date | Mar 29, 2024 |
Journal | Astrophysical Journal Supplement |
Print ISSN | 0067-0049 |
Electronic ISSN | 1538-4365 |
Publisher | American Astronomical Society |
Peer Reviewed | Peer Reviewed |
Volume | 172 |
Issue | 1 |
Pages | 203-218 |
DOI | https://doi.org/10.1086/516592 |
Files
Published Journal Article
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Copyright Statement
© 2007. The American Astronomical Society. All rights reserved. Printed in U.S.A.
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