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Using drift scans to improve astrometry with Spitzer

Ingalls, James G. and Carey, Sean J. and Lowrance, Patrick J. and Grillmair, Carl J. and Stauffer, John R. (2014) Using drift scans to improve astrometry with Spitzer. In: Space Telescopes and Instrumentation 2014: Optical, Infrared, and Millimeter Wave. Proceedings of SPIE. No.9143. Society of Photo-Optical Instrumentation Engineers , Bellingham, WA, Art. No. 91431M. ISBN 978-0-8194-9611-9.

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The Spitzer Space Telescope Infrared Array Camera (IRAC) is the only space-based instrument currently capable of continuous long duration monitoring of brown dwarfs to detect variability and characterize their atmospheres. Any such studies are limited, however, by the accuracy to which we know the positions and distances to these targets (most of which are newly discovered and therefore do not yet have multiple epochs of astrometric data). To that end, we have begun a new initiative to adapt the astrometric drift scanning technique employed by the Hubble Space Telescope to enhance Spitzer measurements of parallaxes and proper motions of brown dwarfs and other targets. A suite of images are taken with a set of sources scanned across the array. This technique reduces random noise by coaddition, and because each target covers multiple pixels we are able to average over residual instrumental distortion and intra-pixel variations. Although these benefits can be realized with appropriate dithering, scanning is much more effcient because we can take data concurrently with the spacecraft motion, covering many pixels without waiting to reposition and settle. In this contribution we demonstrate that the observing mode works and describe our software for analyzing the observations. We outline ongoing efforts towards simultaneously solving for source position and residual distortion. Initial testing shows a factor of more than 2 improvement in the astrometric precision can be obtained with Spitzer. We anticipate being able to measure parallaxes for sources out to about 50 pc, increasing the volume surveyed by a factor of 100 and enabling luminosity measurements of the young population of brown dwarfs in the β Pictoris moving group. This observing mode will be ready for public use around Winter of 2015.

Item Type:Book Section
Related URLs:
URLURL TypeDescription
Ingalls, James G.0000-0003-4714-1364
Carey, Sean J.0000-0002-0221-6871
Lowrance, Patrick J.0000-0001-8014-0270
Grillmair, Carl J.0000-0003-4072-169X
Stauffer, John R.0000-0003-3595-7382
Additional Information:© 2014 SPIE. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Series Name:Proceedings of SPIE
Issue or Number:9143
Record Number:CaltechAUTHORS:20150619-094057932
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Official Citation:James G. Ingalls ; Sean J. Carey ; Patrick J. Lowrance ; Carl J. Grillmair ; John R. Stauffer; Using drift scans to improve astrometry with Spitzer. Proc. SPIE 9143, Space Telescopes and Instrumentation 2014: Optical, Infrared, and Millimeter Wave, 91431M (August 2, 2014); doi:10.1117/12.2056755
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58374
Deposited By: Tony Diaz
Deposited On:19 Jun 2015 16:46
Last Modified:14 Nov 2019 23:48

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