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Proceedings Paper

Weighing black holes using open-loop focus corrections for LGS-AO observations of galaxy nuclei at Gemini Observatory
Author(s): Richard M. McDermid; Davor Krajnovic; Michele Cappellari; Chadwick Trujillo; Julian Christou; Roger L. Davies
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Paper Abstract

We present observations of early-type galaxies with laser guide star adaptive optics (LGS AO) obtained at Gemini North telescope using the NIFS integral field unit (IFU). We employ an innovative technique where the focus compensation due to the changing distance to the sodium layer is made 'open loop', allowing the extended galaxy nucleus to be used only for tip-tilt correction. The purpose of these observations is to determine high spatial resolution stellar kinematics within the nuclei of these galaxies to determine the masses of the super-massive black holes. The resulting data have spatial resolution of 0.2" FWHM or better. This is sufficient to positively constrain the presence of the central black hole in even low-mass early-type galaxies, suggesting that larger samples of such objects could be observed with this technique in the future. The open-loop focus correction technique is a supported queue-observing mode at Gemini, significantly extending the sky coverage in particular for faint, extended guide sources. We also provide preliminary results from tests combining tip/tilt correction from the Gemini peripheral guider with on-axis LGS. The current test system demonstrates feasibility of this mode, providing about a factor 2-3 improvement over natural seeing. With planned upgrades to the peripheral wave-front sensor, we hope to provide close to 100% sky coverage with low Strehl corrections, or 'improved seeing', significantly increasing flux concentration for deep field and extended object studies.

Paper Details

Date Published: 29 July 2010
PDF: 8 pages
Proc. SPIE 7736, Adaptive Optics Systems II, 77365W (29 July 2010); doi: 10.1117/12.856572
Show Author Affiliations
Richard M. McDermid, Gemini Observatory (United States)
Davor Krajnovic, European Organisation for Astronomical Research in the Southern Hemisphere (Germany)
Michele Cappellari, Univ. of Oxford (United Kingdom)
Chadwick Trujillo, Gemini Observatory (United States)
Julian Christou, Gemini Observatory (United States)
Roger L. Davies, Univ. of Oxford (United Kingdom)

Published in SPIE Proceedings Vol. 7736:
Adaptive Optics Systems II
Brent L. Ellerbroek; Michael Hart; Norbert Hubin; Peter L. Wizinowich, Editor(s)

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