منابع مشابه
Comparing Tycho–2 Astrometry with Ucac1
The Tycho–2 Catalogue, released in February 2000, is based on the ESA Hipparcos space mission data and various ground–based catalogs for proper motions. An external comparison of the Tycho–2 astrometry is presented here using the first U.S. Naval Observatory CCD As-trograph Catalog (UCAC1). The UCAC1 data were obtained from observations performed at CTIO between February 1998 and November 1999,...
متن کاملStellar Photometry and Astrometry with Discrete Point Spread Functions
The key features of the MATPHOT algorithm for precise and accurate stellar photometry and astrometry using discrete Point Spread Functions are described. A discrete Point Spread Function (PSF) is a sampled version of a continuous PSF which describes the two-dimensional probability distribution of photons from a point source (star) just above the detector. The shape information about the photon ...
متن کاملPSFs, Photometry, and Astrometry for the ACS/WFC
We develop and present effective PSFs for the F606W filter in the WFC, and then for five other filters. After briefly reviewing the concept of the effective PSF, we show that the WFC PSF varies with position in the detector. We represent the PSF by a 9×10 array of fiducial PSFs, between which a tailor-made PSF is to be interpolated for each star. Fitting these PSFs to star images gives photomet...
متن کاملAccurate Astrometry and Photometry of Saturated and Coronagraphic Point Spread Functions
Accurate astrometry and photometry of saturated and coronagraphic point spread functions (PSFs) are fundamental to both groundand space-based high contrast imaging projects. For ground-based adaptive optics imaging, differential atmospheric refraction and flexure introduce a small drift of the PSF with time, and seeing and sky transmission variations modify the PSF flux distribution. For space-...
متن کاملAstrometry and Near-infrared Photometry of Neptune’s Inner Satellites and Ring Arcs
We report 1.87 lm photometry and astrometry of the inner satellites (Proteus, Larissa, Galatea, and Despina) and ring arcs of Neptune, obtained with the Hubble Space Telescope and its near-infrared camera NICMOS. From comparison with the Voyager data obtained at visible wavelengths, the small bodies orbiting within the ring region of Neptune have a near-infrared albedo consistently low, but hig...
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ژورنال
عنوان ژورنال: Highlights of Astronomy
سال: 1992
ISSN: 1539-2996
DOI: 10.1017/s1539299600009370