arXiv subjects

L. -Y. Chiang

Publications and source records attributed to L. -Y. Chiang.

5 recordsLinked to original sources

arXiv2007

On the Antenna Beam Shape Reconstruction Using Planet Transit

The calibration of the in-flight antenna beam shape and possible beamdegradation is one of the most crucial tasks for the upcoming Planck mission. We examine several effects which could significantly influence the in-flight main beam calibration using planet transit: the problems of the variability of the Jupiter's flux, the antenna temperature and passing of the planets through the main beam. We estimate these effects on the antenna beam shape calibration and calculate the limits on the main beam and far sidelobe measurements, using observations of Jupiter and Saturn. We also discuss possible effects of degradation of the mirror surfaces and specify corresponding parameters which can help us to determine these effects.

astro-ph↗

arXiv2005

Gauss--Legendre Sky Pixelization (GLESP) for CMB maps

A new scheme of sky pixelization is developed for CMB maps. The scheme is based on the Gauss--Legendre polynomials zeros and allows one to create strict orthogonal expansion of the map. A corresponding code has been implemented and comparison with other methods has been done.

astro-ph↗

arXiv2005

First Release of Gauss-Legendre Sky Pixelization (GLESP) software package for CMB analysis

We report the release of the Gauss--Legendre Sky Pixelization (GLESP) software package version 1.0. In this report we present the main features and functions for processing and manipulation of sky signals. Features for CMB polarization is underway and to be incorporated in a future release. Interested readers can visit http://www.glesp.nbi.dk (www.glesp.nbi.dk) and register for receiving the package.

astro-ph↗

arXiv2002

An adaptive filter for the PLANCK Compact Source Catalogue construction

We develop a linear algorithm for extracting extragalactic point sources for the Compact Source Catalogue of the upcoming PLANCK mission. This algorithm is based on a simple top-hat filter in the harmonic domain with an adaptive filtering range which does not require a priori knowledge of the CMB power spectrum and the experiment parameters such as the beam size and shape nor pixel noise level.

astro-ph↗

arXiv2001

Asymmetry of the PLANCK antenna beam shape and its manifestation in the CMB data

We present a new method to extract the beam shape incorporated in the pixelized map of CMB experiments. This method is based on the interplay of the amplitudes and phases of the signal and instrumental noise. By adding controlled white noise onto the map, the phases are perturbed in such a way that the beam shape manifests itself through the mean-squared value of the difference between original and perturbed phases. This method is useful in extracting preliminary antenna beam shape without time-consuming spherical harmonic computations.

astro-ph↗