Visibility science operations with the Keck Interferometer

The visibility science mode of the Keck Interferometer fully transitioned into operations with the successful completion of its operational readiness review in April 2004. The goal of this paper is to describe this science mode and the operations structure that supports it

Astrometry with the Keck-Interferometer: the ASTRA project and its science

The sensitivity and astrometry upgrade ASTRA of the Keck Interferometer is introduced. After a brief overview of the underlying interferometric principles, the technology and concepts of the upgrade are presented. The interferometric dual-field technology of ASTRA will provide the KI with the means to observe two objects simultaneously, and measure the distance between them with a precision eventually better than 100 uas. This astrometric functionality of ASTRA will add a unique observing tool to fields of astrophysical research as diverse as exo-planetary kinematics, binary astrometry, and the investigation of stars accelerated by the massive black hole in the center of the Milky Way as discussed in this contribution.Comment: 22 pages, 10 figures (low resolution), contribution to the summerschool "Astrometry and Imaging with the Very Large Telescope Interferometer", 2 - 13 June, 2008, Keszthely, Hungary, corrected authorlis

First faint dual-field phase-referenced observations on the Keck interferometer

Ground-based long baseline interferometers have long been limited in sensitivity by the short integration periods imposed by atmospheric turbulence. The first observation fainter than this limit was performed on January 22, 2011 when the Keck Interferometer observed a K=11.5 target, about one magnitude fainter than its K=10.3 limit. This observation was made possible by the Dual Field Phase Referencing instrument of the ASTRA project: simultaneously measuring the real-time effects of the atmosphere on a nearby bright guide star, and correcting for it on the faint target, integration time longer than the turbulence time scale are made possible. As a prelude to this demonstration, we first present the implementation of Dual Field Phase Referencing on the interferometer. We then detail its on-sky performance focusing on the accuracy of the turbulence correction, and on the resulting fringe contrast stability. We conclude with a presentation of early results obtained with Laser Guide Star AO and the interferometer.Comment: 10 pages, 12 figures, Proc. SPIE 201

Visibility science operations with the Keck Interferometer

The visibility science mode of the Keck Interferometer fully transitioned into operations with the successful completion of its operational readiness review in April 2004. The goal of this paper is to describe this science mode and the operations structure that supports it

LBT prime focus camera (LBC) control software upgrades

The control software of the Large Binocular Telescope's (LBT) double prime focus cameras (LBC) has been in use for a decade: the software passed acceptance testing in April 2004 and is currently in routine use for science. LBC was the first light instrument of the telescope. Over the last decade of use, the control software has changed as operations with the telescope have evolved. The major updates to the LBC control software since 2004 are described, including details for the upgrade to a single control computer from the current five computer architecture

OVMS-plus at the LBT: disturbance compensation simplified

In this paper we will briefly revisit the optical vibration measurement system (OVMS) at the Large Binocular Telescope (LBT) and how these values are used for disturbance compensation and particularly for the LBT Interferometer (LBTI) and the LBT Interferometric Camera for Near-Infrared and Visible Adaptive Interferometry for Astronomy (LINC-NIRVANA). We present the now centralized software architecture, called OVMS+, on which our approach is based and illustrate several challenges faced during the implementation phase. Finally, we will present measurement results from LBTI proving the effectiveness of the approach and the ability to compensate for a large fraction of the telescope induced vibrations