This paper aims at giving an update on the most versatile Adaptive Optics fed instrument to date, the well
known and successful NACO*. Although NACO is only scheduled for about two more years† at the Very Large
Telescope (VLT), it keeps on evolving with additional operation modes bringing original astronomical results.
The high contrast imaging community uses it creatively as a test-bench for SPHERE‡ and other second generation
planet imagers. A new visible wavefront sensor (WFS) optimized for Laser Guide Star (LGS) operations has
been installed and tested, the cube mode is more and more required for frame selection on bright sources, a
seeing enhancer mode (no tip/tilt correction) is now offered to provide full sky coverage and welcome all kind
of extragalactic applications, etc. The Instrument Operations Team (IOT) and Paranal engineers are currently
working hard at maintaining the instrument overall performances but also at improving them and offering new
capabilities, providing the community with a well tuned and original instrument for the remaining time it is
being used. The present contribution delivers a non-exhaustive overview of the new modes and experiments that
have been carried out in the past months.
In the context of the SPHERE planet finder project, we further develop and characterize a recently proposed
method for the efficient direct detection of exoplanets from the ground using spectral and angular differential
imaging. The method, called ANDROMEDA, combines images appropriately into "pseudo-data", then uses all
of them in a Maximum-Likelihood framework to estimate the position and flux of potential planets orbiting
the observed star. The method's performance is assessed on realistic simulations of images performed by the
SPHERE consortium, and it is applied to experimental data taken by the VLT/NAOS-CONICA instrument.
Astronomical speckle imaging is a well established technique for obtaining diffraction limited images of binary
and multiple stars, low contrast solar features and nearby extended objects such as comets and solar system
planets, with large ground-based telescopes. We have developed a speckle masking code to reconstruct images
of such objects from the corresponding specklegrams. This code uses speckle interferometry for estimating the
Fourier amplitudes and bispectrum for estimating the Fourier phases. In this paper, we discuss a few technical
issues such as: What is the photometric and astrometric accuracy that can be achieved with this code? What is
the closest separation between the components of a binary star that can be clearly resolved with sufficient signal
to noise ratio with this code? What is the maximum dynamic range? What kind of calibration schemes can be used in the absence of a bright calibrator close to the object of interest? We address these questions based on computer simulations. We present a few sample reconstructions from the real data obtained from the SOAR telescope. We also present the details of a technical feasibility study carried out with NACO-cube mode at the VLT.
In the frame of the VLT Planet-Finder project, the phase A system study has demonstrated the feasibility of an extreme adaptive optics system aimed at the direct detection of extrasolar giant planets. The main results of this study are presented in this paper.