MEASURING THE ATMOSPHERIC INFLUENCE ON DIFFERENTIAL ASTROMETRY - A SIMPLE METHOD APPLIED TO WIDE-FIELD CCD FRAMES

Authors
Citation
N. Zacharias, MEASURING THE ATMOSPHERIC INFLUENCE ON DIFFERENTIAL ASTROMETRY - A SIMPLE METHOD APPLIED TO WIDE-FIELD CCD FRAMES, Publications of the Astronomical Society of the Pacific, 108(730), 1996, pp. 1135-1138
Citations number
12
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Astronomy & Astrophysics
Journal title
Publications of the Astronomical Society of the Pacific
ISSN journal
0004-6280 → ACNP
Volume
108
Issue
730
Year of publication
1996
Pages
1135 - 1138
Database
ISI
SICI code
0004-6280(1996)108:730<1135:MTAIOD>2.0.ZU;2-F
Abstract
Sets of short-exposure, guided CCD frames are used to measure the nois e added by the atmosphere to differential astrometric observations. La rge nightly variations that are correlated with the seeing have been f ound in the data obtained over two years at the KPNO and CTIO 0.9-m te lescopes. The rms noise added by the atmosphere, after a linear transf ormation of the raw x,y data, is found to be 3-7 mas, normalized to 10 0-s exposure time and a field of view of 20 arcmin near the zenith. An additional nearly constant noise (base level) of 8.5 mas = 0.012 pixe l is found for the KPNO and 6.0 mas = 0.015 pixel for the CTIO telesco pe. This implies that a ground based, all sky, astrometric survey from guided CCD frames is more likely limited by the base-level noise than by the atmosphere and could reach an accuracy better than 10 mas unde r good seeing conditions.