EDP Sciences
Free Access
Issue
A&A
Volume 427, Number 3, December I 2004
Page(s) 1127 - 1143
Section Celestial mechanics and astrometry
DOI https://doi.org/10.1051/0004-6361:20041481
Published online 16 November 2004


A&A 427, 1127-1143 (2004)
DOI: 10.1051/0004-6361:20041481

Filtration of atmospheric noise in narrow-field astrometry with very large telescopes

P. F. Lazorenko and G. A. Lazorenko

Main Astronomical Observatory, National Academy of Sciencies of the Ukraine, Zabolotnogo 27, 03680 Kyiv-127, Ukraine
    e-mail: laz@mao.kiev.ua

(Received 17 June 2004 / Accepted 19 July 2004)

Abstract
This paper presents a non-classic approach to narrow field astrometry that offers a significant improvement over conventional techniques due to enhanced reduction of atmospheric image motion. The method is based on two key elements: apodization of the entrance pupil and the enhanced virtual symmetry of reference stars. Symmetrization is implemented by setting special weights to each reference star. Thus a reference field itself forms a virtual net filter that effectively attenuates the image motion spectrum. Atmospheric positional error was found to follow a power dependency $\Delta \sim R^{k \mu/2} D^{-k/2+1/3}$ on angular field size R and aperture D; here k is some optional even integer $2 \leq k \leq \sqrt{8N+1}-1$ limited by a number N of reference stars, and $\mu \leq 1$ is a term dependent on k and the magnitude and sky star distribution in the field. As compared to conventional techniques for which k=2, the improvement in accuracy increases by some orders. Limitations to astrometric performance of monopupil large ground-based telescopes are estimated. The total atmospheric and photon noise for at a 10 m telescope at good  0.4'' seeing was found to be, depending on sky star density, 10 to 60  $\mu$as per 10 min exposure in R band. For a 100 m telescope and FWHM =  0.1'' (low-order adaptive optics corrections) the potential accuracy is 0.2 to 2  $\mu$as.


Key words: atmospheric effects -- turbulence -- methods: data analysis -- astrometry -- instrumentation: high angular resolution




© ESO 2004

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.