Adaptive optics system for the Very Large Telescope

1994 ◽  
Author(s):  
Norbert N. Hubin ◽  
Bertrand Theodore ◽  
Patrick Petitjean ◽  
Bernard Delabre
Keyword(s):  
Adaptive Optics ◽  
Large Telescope ◽  
Very Large Telescope ◽  
Adaptive Optics System

scholarly journals NAOMI: the adaptive optics system of the Auxiliary Telescopes of the VLTI

2019 ◽  
Vol 629 ◽  
pp. A41 ◽  
Author(s):  
J. Woillez ◽  
J. A. Abad ◽  
R. Abuter ◽  
E. Aller Carpentier ◽  
J. Alonso ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Single Mode ◽  
Large Telescope ◽  
Wavefront Correction ◽  
Design Performance ◽  
Very Large Telescope ◽  
Fringe Tracking ◽  
Adaptive Optics System ◽  
Atmospheric Seeing

Context. The tip-tilt stabilisation system of the 1.8 m Auxiliary Telescopes of the Very Large Telescope Interferometer was never dimensioned for robust fringe tracking, except when atmospheric seeing conditions are excellent. Aims. Increasing the level of wavefront correction at the telescopes is expected to improve the coupling into the single-mode fibres of the instruments, and enable robust fringe tracking even in degraded conditions. Methods. We deployed a new adaptive optics module for interferometry (NAOMI) on the Auxiliary Telescopes. Results. We present its design, performance, and effect on the observations that are carried out with the interferometric instruments.

scholarly journals Wind-driven halo in high-contrast images

2020 ◽  
Vol 638 ◽  
pp. A98
Author(s):  
F. Cantalloube ◽  
O. J. D. Farley ◽  
J. Milli ◽  
N. Bharmal ◽  
W. Brandner ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Circumstellar Disks ◽  
Spectral Variation ◽  
Post Processing ◽  
Point Spread ◽  
Very Large Telescope ◽  
Spread Function ◽  
Processing Techniques ◽  
Fundamental Limitation ◽  
Adaptive Optics System

Context. The wind-driven halo is a feature that is observed in images that were delivered by the latest generation of ground-based instruments that are equipped with an extreme adaptive optics system and a coronagraphic device, such as SPHERE at the Very Large Telescope (VLT). This signature appears when the atmospheric turbulence conditions vary faster than the adaptive optics loop can correct for. The wind-driven halo is observed as a radial extension of the point spread function along a distinct direction (this is sometimes referred to as the butterfly pattern). When this is present, it significantly limits the contrast capabilities of the instrument and prevents the extraction of signals at close separation or extended signals such as circumstellar disks. This limitation is consequential because it contaminates the data for a substantial fraction of the time: about 30% of the data produced by the VLT/SPHERE instrument are affected by the wind-driven halo. Aims. This paper reviews the causes of the wind-driven halo and presents a method for analyzing its contribution directly from the scientific images. Its effect on the raw contrast and on the final contrast after post-processing is demonstrated. Methods. We used simulations and on-sky SPHERE data to verify that the parameters extracted with our method can describe the wind-driven halo in the images. We studied the temporal, spatial, and spectral variation of these parameters to point out its deleterious effect on the final contrast. Results. The data-driven analysis we propose provides information to accurately describe the wind-driven halo contribution in the images. This analysis confirms that this is a fundamental limitation of the finally reached contrast performance. Conclusions. With the established procedure, we will analyze a large sample of data delivered by SPHERE in order to propose post-processing techniques that are tailored to removing the wind-driven halo.

scholarly journals A FOSSIL BULGE GLOBULAR CLUSTER REVEALED BY VERY LARGE TELESCOPE MULTI-CONJUGATE ADAPTIVE OPTICS

2011 ◽  
Vol 737 (1) ◽  
pp. 31 ◽  
Author(s):  
Sergio Ortolani ◽  
Beatriz Barbuy ◽  
Yazan Momany ◽  
Ivo Saviane ◽  
Eduardo Bica ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Globular Cluster ◽  
Large Telescope ◽  
Very Large Telescope

Large-telescope natural guide star adaptive optics system

1994 ◽  
Author(s):  
David C. Redding ◽  
Mark H. Milman ◽  
Laura Needels
Keyword(s):  
Adaptive Optics ◽  
Large Telescope ◽  
Guide Star ◽  
Adaptive Optics System

scholarly journals Extremely Large Telescopes on the Antarctic plateau

2005 ◽  
Vol 13 ◽  
pp. 956-957
Author(s):  
J.S. Lawrence
Keyword(s):  
Adaptive Optics ◽  
Turbulence Structure ◽  
Large Telescope ◽  
Dome A ◽  
Antarctic Plateau ◽  
Guide Star ◽  
Laser Guide ◽  
Large Telescopes ◽  
The Antarctic ◽  
Adaptive Optics System

AbstractThe primary limitation to the performance of any large ground-based telescope is the atmospheric properties of its site, particularly the sky emission and the turbulence structure. There are several sites on the Antarctic plateau (South Pole, Dome C and Dome A) for which the increase in infrared sensitivity relative to a mid-latitude site should be as much as two orders of magnitude. The unique turbulent structure above Dome C indicates that an extremely large telescope equipped with only a natural guide star adaptive optics system should achieve equivalent resolution to a mid-latitude extremely large telescope with a multi-conjugate multi-laser guide star system.

scholarly journals Detection and characterization of two VLM binaries: LP 1033-31 and LP 877-72

2020 ◽  
Vol 498 (1) ◽  
pp. 737-749
Author(s):  
Subhajeet Karmakar ◽  
A S Rajpurohit ◽  
F Allard ◽  
D Homeier
Keyword(s):  
Adaptive Optics ◽  
Spectral Type ◽  
Near Infrared ◽  
Binding Energies ◽  
Secondary Component ◽  
Large Telescope ◽  
Very Large Telescope ◽  
Adaptive Optics Imaging ◽  
M Dwarf

ABSTRACT Using the high-resolution near-infrared adaptive optics imaging from the NaCo instrument at the Very Large Telescope, we report the discovery of a new binary companion to the M-dwarf LP 1033-31 and also confirm the binarity of LP 877-72. We have characterized both the stellar systems and estimated the properties of their individual components. We have found that LP 1033-31 AB with the spectral type of M4.5+M4.5 has a projected separation of 6.7 ± 1.3 AU. Whereas with the spectral type of M1+M4, the projected separation of LP 877-72 AB is estimated to be 45.8 ± 0.3 AU. The binary companions of LP 1033-31 AB are found to have similar masses, radii, effective temperatures, and log g with the estimated values of 0.20 ± 0.04 $\rm {M}_{\odot }$, 0.22 ± 0.03 $\rm {R}_{\odot }$, and 3200 K, 5.06 ± 0.04. However, the primary of LP 877-72 AB is found to be twice as massive as the secondary with the derived mass of 0.520 ± 0.006 $\rm {M}_{\odot }$. The radius and log g for the primary of LP 877-72 AB are found to be 1.8 and 0.95 times that of the secondary component with the estimated values of 0.492 ± 0.011 $\rm {R}_{\odot }$ and 4.768 ± 0.005, respectively. With an effective temperature of 3750 ± 15 K, the primary of LP 877-72 AB is also estimated to be ∼400 K hotter than the secondary component. We have also estimated the orbital period of LP 1033-31 and LP 877-72 to be ∼28 and ∼349 yr, respectively. The binding energies for both systems are found to be >1043 erg, which signifies that both systems are stable.

scholarly journals The VLT Interferometer

1994 ◽  
Vol 158 ◽  
pp. 143-150
Author(s):  
T. R. Bedding ◽  
J. M. Beckers ◽  
M. Faucherre ◽  
N. Hubin ◽  
B. Koehler ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Near Infrared ◽  
High Sensitivity ◽  
Large Telescope ◽  
Wavefront Correction ◽  
Wavefront Aberrations ◽  
Very Large Telescope ◽  
Infrared Wavelengths ◽  
Very High

One of the observing modes available with the ESO Very Large Telescope will be coherent combination of the light received by up to four 8 m unit telescopes and several 1.8 m auxiliary telescopes. The location of the main telescopes is fixed, while auxiliary telescopes can be moved among some 30 observing stations. The locations of these stations were chosen to augment the (u, v) coverage of the unit telescopes as well as to function as an independent interferometric array.The 8 m telescopes will be equipped with adaptive optics to correct for seeing-induced wavefront aberrations. This wavefront correction will be complete at near-infrared wavelengths, giving the interferometer very high sensitivity in this spectral regime. This paper gives a brief description of the VLT Interferometer and an update on its status.

scholarly journals The University of Texas 7.6-m Telescope

1984 ◽  
Vol 79 ◽  
pp. 789-816
Author(s):  
Robert G. Tull
Keyword(s):  
Soviet Union ◽  
Adaptive Optics ◽  
Significant Advance ◽  
Large Telescope ◽  
University Of Texas ◽  
The Soviet Union ◽  
Very Large Telescope ◽  
Western Development ◽  
The Cost ◽  
The University

In late 1979 a plan to build a very large telescope was presented to University of Texas President Peter Flawn. A small startup budget was subsequently granted by the University administration, and we asked Aden and Marjorie Meinel to carry out a design concept study, which they completed in early 1980. Following their report, a study contract was awarded to the Western Development Laboratories Division of Ford Aerospace & Communications Corp., for a preliminary design and cost estimate.It is generally agreed that construction of monolithic mirrors up to 8-10 meters aperture is within current technology. The major concern that has prevented construction of telescopes larger than the Palomar 5-m telescope outside the Soviet Union has been cost; it has been shown (Meinel and Meinel, 1980a) that the single most important item in determining the cost of a large telescope is the weight of its primary mirror. We chose a monolithic, lightweight 7.6-m (300-inch) mirror as representing a significant advance from presently existing telescope apertures while also being well within the current state-of-the-art. Because a lightweight mirror cannot support its figure against gravity and other disturbances as well as can a conventional thick mirror, we have investigated methods of active control of the mirror's figure. The now maturing technology of adaptive optics (Hardy 1980, 1981, 1982) has been drawn upon extensively in planning this telescope. Results of finite element analyses of an ultra-lightweight monolithic 7.6-m mirror blank have been published (Ray et.al., 1982, 1983). A description of the proposed mirror figure monitoring system has been given (Tull and Young, 1983).

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