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Proceedings Paper

Status and new developments with the Keck I near-infrared tip-tilt sensor
Author(s): Bruno Femenía Castellá; Peter Wizinowich; Rachel Rampy; Sylvain Cetre; Scott Lilley; Jim Lyke; Sam Ragland; Paul Stomski; Marcos van Dam
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Paper Abstract

The sky coverage and performance of Laser Guide Star (LGS) adaptive optics (AO) systems is limited by the Natural Guide Star (NGS) used for low order correction (tip-tilt and defocus modes). This limitation can be reduced by measuring image motion of the NGS in the near-infrared where it is partially corrected by the LGS AO system and where stars are generally several magnitudes brighter than at visible wavelengths. We have integrated a Near-InfraRed Tip-Tilt Sensor (NIRTTS) with the Keck I telescopes LGS AO system. The sensor is a H2RG-based near-infrared camera with 0.05 arcsecond pixels. Low noise at high sample rates is achieved by only reading a small region of interest, from 2x2 to 16x16 pixels, centered on an NGS anywhere in an 100 arc second diameter field. The sensor operates at either Ks or H-band using light reflected by a choice of dichroic beam-splitters located in front of the OSIRIS integral field spectrograph. The implementation of the NIRTTS involved modifications to the AO bench, real-time control system, higher-level controls and operations software. NIRTTS is nearly ready for science operation in shared-risk mode. We are also implementing a number of enhancements to the NIRTTS system which involve substantial changes to the operations software. This work presents an update of the work performed since the NIRTTS system was reported in Ref. 1 and Ref. 2.

Paper Details

Date Published: 26 July 2016
PDF: 15 pages
Proc. SPIE 9909, Adaptive Optics Systems V, 990925 (26 July 2016); doi: 10.1117/12.2233173
Show Author Affiliations
Bruno Femenía Castellá, W. M. Keck Observatory (United States)
Peter Wizinowich, W. M. Keck Observatory (United States)
Rachel Rampy, W. M. Keck Observatory (United States)
Sylvain Cetre, W. M. Keck Observatory (United States)
Scott Lilley, W. M. Keck Observatory (United States)
Jim Lyke, W. M. Keck Observatory (United States)
Sam Ragland, W. M. Keck Observatory (United States)
Paul Stomski, W. M. Keck Observatory (United States)
Marcos van Dam, Flat Wavefronts (New Zealand)


Published in SPIE Proceedings Vol. 9909:
Adaptive Optics Systems V
Enrico Marchetti; Laird M. Close; Jean-Pierre Véran, Editor(s)

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