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Proceedings Paper

ASTROCAM: an Offner re-imaging 1024 x 1024 InSb camera for near-infrared astrometry on the USNO 1.55 m telescope
Author(s): Jacqueline Fischer; Frederick J. Vrba; Douglas W. Toomey; Bob L. Lucke; Shu-i Wang; Arne A. Henden; Joseph L. Robichaud; Peter M. Onaka; Brian Hicks; Frederick H. Harris; Werner E. Stahlberger; Kris E. Kosakowski; Charles C. Dudley; Kenneth J. Johnston
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Paper Abstract

In order to extend the US Naval Observatory (USNO) small-angle astrometric capabilities to near infrared wavelengths we have designed and manufactured a 1024 x 1024 InSb re-imaging infrared camera equipped with an array selected from the InSb ALADDIN (Advanced Large Area Detector Development in InSb) development program and broadband and narrowband 0.8 - 3.8 μm filters. Since the USNO 1.55-m telescope is optimized for observations at visible wavelengths with an oversized secondary mirror and sky baffles, the straylight rejection capabilities of the ASTROCAM Lyot stop and baffles are of critical importance for its sensitivity and flat- fielding capabilities. An Offner relay was chosen for the heart of the system and was manufactured from the same melt of aluminum alloy to ensure homologous contraction from room temperature to 77 K. A blackened cone was installed behind the undersized hole (the Lyot stop) in the Offner secondary. With low distortion, a well-sampled point spread function, and a large field of view, the system is well suited for astrometry. It is telecentric, so any defocus will not result in a change of image scale. The DSP-based electronics allow readout of the entire array with double-correlated sampling in 0.19 seconds, but shorter readout is possible with single sampling or by reading out only small numbers of subarrays. In this paper we report on the optical, mechanical, and electronic design of the system and present images and results on the sensitivity and astrometric stability obtained with the system, now operating routinely at the 1.55-m telescope with a science-grade ALADDIN array.

Paper Details

Date Published: 7 March 2003
PDF: 14 pages
Proc. SPIE 4841, Instrument Design and Performance for Optical/Infrared Ground-based Telescopes, (7 March 2003); doi: 10.1117/12.461033
Show Author Affiliations
Jacqueline Fischer, Naval Research Lab. (United States)
Frederick J. Vrba, U.S. Naval Observatory (United States)
Douglas W. Toomey, Mauna Kea Infrared, LLC (United States)
Bob L. Lucke, Naval Research Lab. (United States)
Shu-i Wang, Univ. of Chicago (United States)
Arne A. Henden, U.S. Naval Observatory (United States)
Univ. Space Research Association (United States)
Joseph L. Robichaud, SSG Precision Optronics, Inc. (United States)
Peter M. Onaka, Applied Designs (United States)
Brian Hicks, Naval Research Lab. (United States)
Frederick H. Harris, U.S. Naval Observatory (United States)
Werner E. Stahlberger, CAD Services (United States)
Kris E. Kosakowski, SSG Precision Optronics, Inc. (United States)
Charles C. Dudley, Naval Research Lab. (United States)
Kenneth J. Johnston, U.S. Naval Observatory (United States)

Published in SPIE Proceedings Vol. 4841:
Instrument Design and Performance for Optical/Infrared Ground-based Telescopes
Masanori Iye; Alan F. M. Moorwood, Editor(s)

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