SINFONI is an adaptive optics assisted near-infrared integral field spectrometer for the ESO VLT. The Adaptive Optics Module (built by the ESO Adaptive Optics Group) is a 60-elements curvature-sensor based system, designed for operations with natural or sodium laser guide stars. The near-infrared integral field spectrometer SPIFFI (built by the Infrared Group of MPE) provides simultaneous spectroscopy of 32 x 32 spatial pixels, and a spectral resolving power of up to 3300. The adaptive optics module is in the phase of integration; the spectrometer is presently tested in the laboratory. We provide an overview of the project, with particular emphasis on the problems encountered in designing and building an adaptive optics assisted spectrometer. 1. SINFONI: ADAPTIVE OPTICS AND INTEGRAL FIELD SPECTROSCOPY SINFONI (SINgle Faint Object Near-IR Investigation) is an adaptive optics assisted near infrared integral field spectrometer mounted to the European Southern Observatory (ESO) VLT (Very Large Telescope). The instrument is a combination ofthe Adaptive Optics module [1], a clone ofMACAO (Multiple Application Curvature Adaptive Optics), developed and built by ESO, and of the near infrared integral field spectrograph SPIFFI (SPectrograph for Infrared Faint Field Imaging) [2], developed and built by the Max-Planck-Institute for extraterrestrial Physics (MPE).Currently, ESO offers two state-of-the-art near infrared instruments at the VLT: ISAAC [3] for seeing limited infrared imaging and spectroscopy, and NAOS/CONICA [4,5] for high order adaptive optics imaging and low-resolution spectroscopy. However, spectroscopy of faint objects with diffraction limited angular resolution at an eight-meter telescope will strongly benefit from a dedicated instrument, which combines the following characteristics: first, diffraction limited observations at near infrared wavelengths, optimized for faint wave-front reference stars and laser guide star operations; second, instantaneous spectroscopy of a two dimensional field with sufficiently high spectral resolution for deep observations between the night sky emission lines.Both partner institutes collected extensive experience with diffraction-limited spectroscopy with their instruments ADONIS/SHARP [6] at the La Silla 3.6 m telescope, and ALFA/3D [7] at the Calar Alto Observatory 3.5 m telescope. Our conclusion is that when observing with adaptive optics, integral field spectroscopy gains significantly over long-slit spectroscopy and Fabry-Perot imaging. The latter suffers significantly from the variation of the sky emission and the point-spread-function (PSF) between consecutive images, and consumes exorbitant observing time for large wavelength coverage. Long-slit spectroscopy, on the other hand, lacks the essential two-dimensional information for decomposing the spatial flux distribution, and loses most ofthe source flux for a diffraction limited slit width and moderate correction of the atmospheric aberrations. In addition, flexure within the instruments complicates the acquisition of...

The new 8.4m LBT adaptive secondary AO system, with its novel pyramid wavefront sensor, was used to produce very high Strehl ( 75% at 2.16µm) near infrared narrowband (Brγ: 2.16µm and [FeII]: 1.64µm) images of 47 young (∼ 1 Myr) Orion Trapezium θ 1 Ori cluster members. The inner ∼ 41 × 53 ′′ of the 01 The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona university system; cluster was imaged at spatial resolutions of ∼ 0.050 ′′ (at 1.64µm). A combination of high spatial resolution and high S/N yielded relative binary positions to ∼ 0.5 mas accuracies. Including previous speckle data, we analyze a 15 year baseline of high-resolution observations of this cluster. We are now sensitive to relative proper motions of just ∼ 0.3 mas/yr (0.6 km/s at 450 pc) this is a ∼ 7× improvement in orbital velocity accuracy compared to previous efforts. We now detect clear orbital motions in the θ 1 Ori B 2 B 3 system of 4.9 ± 0.3 km/s and 7.2 ± 0.8 km/s in the θ 1 Ori A 1 A 2 system (with correlations of PA vs. time at > 99% confidence). All five members of the θ 1 Ori B system appear likely as a gravitationally bound "mini-cluster". The very lowest mass member of the θ 1 Ori B system (B 4 ; mass ∼ 0.2M ⊙ ) has, for the first time, a clearly detected motion (at 4.3 ± 2.0 km/s; correlation=99.7%) w.r.t B 1 . However, B 4 is most likely in an long-term unstable (non-hierarchical) orbit and may "soon" be ejected from this "mini-cluster". This "ejection" process could play a major role in the formation of low mass stars and brown dwarfs.

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MACAO stands for Multi Application Curvature Adaptive Optics. A similar concept is applied to fulfill the need for wavefront correction for several VLT instruments. MACAO-VLTI is one of these built in 4 copies in order to equip the Coude focii of the ESO VLT's. The optical beams will then be corrected before interferometric recombination in the VLTI (Very Large Telescope Interferometer) laboratory. MACAO-VLTI uses a 60 elements bimorph mirror and curvature wavefront sensor. A custom made board processes the signals provided by the wavefront detectors, 60 Avalanche Photo-diodes, and transfer them to a commercial Power PC CPU board for Real Time Calculation. Mirrors Commands are sent to a High Voltage amplifier unit through an optical fiber link. The tip-tilt correction is done by a dedicated Tip-tilt mount holding the deformable mirror. The whole wavefront is located at the Coude focus. Software is developed in house and is ESO compatible. Expected performance is a Strehl ratio sligthly under 60% at 2.2 micron for bright reference sources (star V<10) and a limiting magnitude of 17.5 (Strehl ~0.1). The four systems will be installed in Paranal successively, the first one being planned for June 2003 and the last one for June 2004.