Share Email Print

Proceedings Paper

Simulations of JWST MIRI 4QPM coronagraphs operations and performances
Author(s): Charles-Philippe Lajoie; Rémi Soummer; Dean C. Hines; George H. Rieke
Format Member Price Non-Member Price
PDF $17.00 $21.00

Paper Abstract

We present the results of ongoing coronagraphic simulations aimed at designing strategies for optimizing oper- ations of the coronagraphs in the mid-infrared instrument (MIRI) on-board the James Webb Space Telescope (JWST). In particular, the adverse effects on the point spread function caused by the phase mask coronagraphs and the observatory slew accuracy are known to limit our ability to position stars at the center of the coron- agraph. Here, we investigate these two effects on our ability to perform target acquisition (TA) and consider different scenarios involving single and multiple acquisitions to mitigate them. We assess the performance of the coronagraphs under various slew accuracy models as well as noise sources. In general, we find that scenarios that require fewer acquisitions yield final positions with smaller dispersions but larger offsets. Our Single TA scenario yields the best repeatability for all three slew accuracy models that we considered although a dual Twin TA strategy generally yields more accurate centering. We also investigate the use of the contamination control cover (CCC) inside MIRI during TA of bright objects, and ways to mitigate the resulting latent images when the CCC is not used. Our results are expressed in terms of achieved contrast with simple, single reference star subtraction. Given our preliminary prescription for latency, our simulations suggest that the CCC need not be used except for very bright sources; detailed guidelines will require additional information on the latent image decay time scale. Furthermore, we find that contrast is dependent on the observatory slew accuracy at any wavelength. The highest contrast is achieved with the highest slew accuracy model, although the background photon noise limits the contrast at longer wavelengths.

Paper Details

Date Published: 28 August 2014
PDF: 11 pages
Proc. SPIE 9143, Space Telescopes and Instrumentation 2014: Optical, Infrared, and Millimeter Wave, 91433R (28 August 2014); doi: 10.1117/12.2056284
Show Author Affiliations
Charles-Philippe Lajoie, Space Telescope Science Institute (United States)
Rémi Soummer, Space Telescope Science Institute (United States)
Dean C. Hines, Space Telescope Science Institute (United States)
George H. Rieke, Steward Observatory, The Univ. of Arizona (United States)

Published in SPIE Proceedings Vol. 9143:
Space Telescopes and Instrumentation 2014: Optical, Infrared, and Millimeter Wave
Jacobus M. Oschmann Jr.; Mark Clampin; Giovanni G. Fazio; Howard A. MacEwen, Editor(s)

© SPIE. Terms of Use
Back to Top
Sign in to read the full article
Create a free SPIE account to get access to
premium articles and original research
Forgot your username?